diff --git a/.github/workflows/charm-test.yaml b/.github/workflows/charm-test.yaml index a0f8a92b0..ac08a8baf 100644 --- a/.github/workflows/charm-test.yaml +++ b/.github/workflows/charm-test.yaml @@ -11,8 +11,6 @@ jobs: uses: ./.github/workflows/charm-build.yaml lint: - # Delete this if statement once charms are updated and include tox. - if: ${{ 1 }} == ${{ 2 }} name: Lint runs-on: ubuntu-latest strategy: @@ -29,8 +27,6 @@ jobs: - name: Run linters run: tox -e lint unit-tests: - # Delete this if statement once charms are updated and include tox. - if: ${{ 1 }} == ${{ 2 }} name: Unit tests runs-on: ubuntu-latest strategy: diff --git a/charms/jimm-k8s/.flake8 b/charms/jimm-k8s/.flake8 index 8ef84fcd4..02ffd85c4 100644 --- a/charms/jimm-k8s/.flake8 +++ b/charms/jimm-k8s/.flake8 @@ -1,5 +1,5 @@ [flake8] -max-line-length = 99 +max-line-length = 120 select: E,W,F,C,N exclude: venv @@ -7,3 +7,4 @@ exclude: build dist *.egg_info +ignore = W503 diff --git a/charms/jimm-k8s/CONTRIBUTING.md b/charms/jimm-k8s/CONTRIBUTING.md index e8fc89244..58562b2cb 100644 --- a/charms/jimm-k8s/CONTRIBUTING.md +++ b/charms/jimm-k8s/CONTRIBUTING.md @@ -1,29 +1,64 @@ -# jimm +# Contributing + +## Overview + +This documents explains the processes and practices recommended for contributing enhancements to +this operator. + +- If you would like to chat with us about your use-cases, you can reach + us at [Discourse](https://chat.charmhub.io/charmhub/channels/jaas). +- Familiarising yourself with the [Charmed Operator Framework](https://juju.is/docs/sdk) library + will help you a lot when working on new features or bug fixes. +- All enhancements require review before being merged. Code review typically examines + - code quality + - test coverage + - user experience for Juju administrators this charm. +- Please help us out in ensuring easy to review branches by rebasing your pull request branch onto + the `main` branch. This also avoids merge commits and creates a linear Git commit history. ## Developing -Create and activate a virtualenv with the development requirements: +You can create an environment for development with `tox`: + +```shell +virtualenv -p python3 venv +source venv/bin/activate +pip install -r requirements-dev.txt +pip install tox +``` + +The charm additionally requires the following relations: +- ingress, interface: ingress +- database, interface: postgresql_client +- vault, interface: vault-kv +- certificates, interface: tls-certificates - virtualenv -p python3 venv - source venv/bin/activate - pip install -r requirements-dev.txt +### Testing -## Intended use case +```shell +tox -e fmt # update your code according to linting rules +tox -e lint # code style +tox -e unit # unit tests +tox -e integration # integration tests +tox # runs 'lint' and 'unit' environments +``` -This JIMM operator charm is intended for deploying the -Juju Intelligent Model Manager in a k8s cluster. The charm -does not use relations to connect to postgresql and/or -vault as it is assumed those services could be deployed -in a different model. -## Roadmap +## Build charm -* Add postgresql relation -* Add vault relation (when a k8s vault charm becomes available) +Build the charm in this git repository using: -## Testing +```shell +charmcraft pack +``` -The Python operator framework includes a very nice harness for testing -operator behaviour without full deployment. Just `run_tests` : +### Deploy - ./run_tests +```bash +# Create a model +juju add-model dev +# Enable DEBUG logging +juju model-config logging-config="=INFO;unit=DEBUG" +# Deploy the charm +juju deploy ./juju-jimm-k8s_ubuntu-22.04-amd64.charm +``` diff --git a/charms/jimm-k8s/README.md b/charms/jimm-k8s/README.md index 9d704239a..11e5d2c0d 100644 --- a/charms/jimm-k8s/README.md +++ b/charms/jimm-k8s/README.md @@ -36,6 +36,24 @@ Create and activate a virtualenv with the development requirements: ## Testing The Python operator framework includes a very nice harness for testing -operator behaviour without full deployment. Just `run_tests` : - - ./run_tests +operator behaviour without full deployment. The test suite can be run +using `tox`. You can either `pip install tox` system-wide or create a +virtual env and install tox there as follows +``` +python3 -m venv venv +source ./venv/bin/activate +pip install tox +``` +At this point you can run tests/linters/formatters. +``` +tox -e fmt +tox -e lint +tox -e unit +tox -e integration +``` +Note that integration tests will build the charm and deploy it to a local +microk8s controller (which must be setup prior to running the integration test). +To switch the integration test to use a locally built charm use +``` +tox -e integration -- --localCharm +``` diff --git a/charms/jimm-k8s/actions.yaml b/charms/jimm-k8s/actions.yaml index f2e811485..31604eff9 100644 --- a/charms/jimm-k8s/actions.yaml +++ b/charms/jimm-k8s/actions.yaml @@ -1,3 +1,2 @@ # Copyright 2022 Canonical Ltd # See LICENSE file for licensing details. - diff --git a/charms/jimm-k8s/charmcraft.yaml b/charms/jimm-k8s/charmcraft.yaml index fdbe7d035..85812501d 100644 --- a/charms/jimm-k8s/charmcraft.yaml +++ b/charms/jimm-k8s/charmcraft.yaml @@ -4,10 +4,22 @@ type: "charm" parts: charm: charm-python-packages: [setuptools] + charm-binary-python-packages: + - cryptography + - jsonschema + - PyYAML + - attrs + - importlib-resources + - urllib3 + - zipp bases: + # This run-on is not as strict as the machine charm + # as the jimm-server runs in a container. + # So the only restriction for build-on vs run-on is + # the charm code. - build-on: - - name: "ubuntu" - channel: "20.04" + - name: "ubuntu" + channel: "20.04" run-on: - - name: "ubuntu" - channel: "20.04" + - name: "ubuntu" + channel: "20.04" diff --git a/charms/jimm-k8s/config.yaml b/charms/jimm-k8s/config.yaml index 65c7caeed..d1e098730 100644 --- a/charms/jimm-k8s/config.yaml +++ b/charms/jimm-k8s/config.yaml @@ -25,9 +25,6 @@ options: description: | Whitespace separated list of candid users (or groups) that are made controller admins by default. - dns-name: - type: string - description: Public DNS hostname that JIMM is being served from. log-level: type: string description: | @@ -53,16 +50,10 @@ options: uuid: type: string description: The UUID advertised by the JIMM controller. - vault-url: - type: string - description: Vault URL. - vault-role-id: - type: string - description: Vault Role ID. - vault-token: - type: string - description: Vault Token. juju-dashboard-location: type: string default: https://jaas.ai/models description: URL of the Juju Dashboard for this controller. + dns-name: + type: string + description: DNS hostname that JIMM is being served from. diff --git a/charms/jimm-k8s/lib/charms/data_platform_libs/v0/database_requires.py b/charms/jimm-k8s/lib/charms/data_platform_libs/v0/database_requires.py new file mode 100644 index 000000000..53d619128 --- /dev/null +++ b/charms/jimm-k8s/lib/charms/data_platform_libs/v0/database_requires.py @@ -0,0 +1,496 @@ +# Copyright 2022 Canonical Ltd. +# +# Licensed under the Apache License, Version 2.0 (the "License"); +# you may not use this file except in compliance with the License. +# You may obtain a copy of the License at +# +# http://www.apache.org/licenses/LICENSE-2.0 +# +# Unless required by applicable law or agreed to in writing, software +# distributed under the License is distributed on an "AS IS" BASIS, +# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. +# See the License for the specific language governing permissions and +# limitations under the License. + +"""Relation 'requires' side abstraction for database relation. + +This library is a uniform interface to a selection of common database +metadata, with added custom events that add convenience to database management, +and methods to consume the application related data. + +Following an example of using the DatabaseCreatedEvent, in the context of the +application charm code: + +```python + +from charms.data_platform_libs.v0.database_requires import DatabaseRequires + +class ApplicationCharm(CharmBase): + # Application charm that connects to database charms. + + def __init__(self, *args): + super().__init__(*args) + + # Charm events defined in the database requires charm library. + self.database = DatabaseRequires(self, relation_name="database", database_name="database") + self.framework.observe(self.database.on.database_created, self._on_database_created) + + def _on_database_created(self, event: DatabaseCreatedEvent) -> None: + # Handle the created database + + # Create configuration file for app + config_file = self._render_app_config_file( + event.username, + event.password, + event.endpoints, + ) + + # Start application with rendered configuration + self._start_application(config_file) + + # Set active status + self.unit.status = ActiveStatus("received database credentials") +``` + +As shown above, the library provides some custom events to handle specific situations, +which are listed below: + +— database_created: event emitted when the requested database is created. +— endpoints_changed: event emitted when the read/write endpoints of the database have changed. +— read_only_endpoints_changed: event emitted when the read-only endpoints of the database + have changed. Event is not triggered if read/write endpoints changed too. + +If it is needed to connect multiple database clusters to the same relation endpoint +the application charm can implement the same code as if it would connect to only +one database cluster (like the above code example). + +To differentiate multiple clusters connected to the same relation endpoint +the application charm can use the name of the remote application: + +```python + +def _on_database_created(self, event: DatabaseCreatedEvent) -> None: + # Get the remote app name of the cluster that triggered this event + cluster = event.relation.app.name +``` + +It is also possible to provide an alias for each different database cluster/relation. + +So, it is possible to differentiate the clusters in two ways. +The first is to use the remote application name, i.e., `event.relation.app.name`, as above. + +The second way is to use different event handlers to handle each cluster events. +The implementation would be something like the following code: + +```python + +from charms.data_platform_libs.v0.database_requires import DatabaseRequires + +class ApplicationCharm(CharmBase): + # Application charm that connects to database charms. + + def __init__(self, *args): + super().__init__(*args) + + # Define the cluster aliases and one handler for each cluster database created event. + self.database = DatabaseRequires( + self, + relation_name="database", + database_name="database", + relations_aliases = ["cluster1", "cluster2"], + ) + self.framework.observe( + self.database.on.cluster1_database_created, self._on_cluster1_database_created + ) + self.framework.observe( + self.database.on.cluster2_database_created, self._on_cluster2_database_created + ) + + def _on_cluster1_database_created(self, event: DatabaseCreatedEvent) -> None: + # Handle the created database on the cluster named cluster1 + + # Create configuration file for app + config_file = self._render_app_config_file( + event.username, + event.password, + event.endpoints, + ) + ... + + def _on_cluster2_database_created(self, event: DatabaseCreatedEvent) -> None: + # Handle the created database on the cluster named cluster2 + + # Create configuration file for app + config_file = self._render_app_config_file( + event.username, + event.password, + event.endpoints, + ) + ... + +``` +""" + +import json +import logging +from collections import namedtuple +from datetime import datetime +from typing import List, Optional + +from ops.charm import ( + CharmEvents, + RelationChangedEvent, + RelationEvent, + RelationJoinedEvent, +) +from ops.framework import EventSource, Object +from ops.model import Relation + +# The unique Charmhub library identifier, never change it +LIBID = "0241e088ffa9440fb4e3126349b2fb62" + +# Increment this major API version when introducing breaking changes +LIBAPI = 0 + +# Increment this PATCH version before using `charmcraft publish-lib` or reset +# to 0 if you are raising the major API version. +LIBPATCH = 4 + +logger = logging.getLogger(__name__) + + +class DatabaseEvent(RelationEvent): + """Base class for database events.""" + + @property + def endpoints(self) -> Optional[str]: + """Returns a comma separated list of read/write endpoints.""" + return self.relation.data[self.relation.app].get("endpoints") + + @property + def password(self) -> Optional[str]: + """Returns the password for the created user.""" + return self.relation.data[self.relation.app].get("password") + + @property + def read_only_endpoints(self) -> Optional[str]: + """Returns a comma separated list of read only endpoints.""" + return self.relation.data[self.relation.app].get("read-only-endpoints") + + @property + def replset(self) -> Optional[str]: + """Returns the replicaset name. + + MongoDB only. + """ + return self.relation.data[self.relation.app].get("replset") + + @property + def tls(self) -> Optional[str]: + """Returns whether TLS is configured.""" + return self.relation.data[self.relation.app].get("tls") + + @property + def tls_ca(self) -> Optional[str]: + """Returns TLS CA.""" + return self.relation.data[self.relation.app].get("tls-ca") + + @property + def uris(self) -> Optional[str]: + """Returns the connection URIs. + + MongoDB, Redis, OpenSearch and Kafka only. + """ + return self.relation.data[self.relation.app].get("uris") + + @property + def username(self) -> Optional[str]: + """Returns the created username.""" + return self.relation.data[self.relation.app].get("username") + + @property + def version(self) -> Optional[str]: + """Returns the version of the database. + + Version as informed by the database daemon. + """ + return self.relation.data[self.relation.app].get("version") + + +class DatabaseCreatedEvent(DatabaseEvent): + """Event emitted when a new database is created for use on this relation.""" + + +class DatabaseEndpointsChangedEvent(DatabaseEvent): + """Event emitted when the read/write endpoints are changed.""" + + +class DatabaseReadOnlyEndpointsChangedEvent(DatabaseEvent): + """Event emitted when the read only endpoints are changed.""" + + +class DatabaseEvents(CharmEvents): + """Database events. + + This class defines the events that the database can emit. + """ + + database_created = EventSource(DatabaseCreatedEvent) + endpoints_changed = EventSource(DatabaseEndpointsChangedEvent) + read_only_endpoints_changed = EventSource(DatabaseReadOnlyEndpointsChangedEvent) + + +Diff = namedtuple("Diff", "added changed deleted") +Diff.__doc__ = """ +A tuple for storing the diff between two data mappings. + +— added — keys that were added. +— changed — keys that still exist but have new values. +— deleted — keys that were deleted. +""" + + +class DatabaseRequires(Object): + """Requires-side of the database relation.""" + + on = DatabaseEvents() + + def __init__( + self, + charm, + relation_name: str, + database_name: str, + extra_user_roles: str = None, + relations_aliases: List[str] = None, + ): + """Manager of database client relations.""" + super().__init__(charm, relation_name) + self.charm = charm + self.database = database_name + self.extra_user_roles = extra_user_roles + self.local_app = self.charm.model.app + self.local_unit = self.charm.unit + self.relation_name = relation_name + self.relations_aliases = relations_aliases + self.framework.observe( + self.charm.on[relation_name].relation_joined, self._on_relation_joined_event + ) + self.framework.observe( + self.charm.on[relation_name].relation_changed, self._on_relation_changed_event + ) + + # Define custom event names for each alias. + if relations_aliases: + # Ensure the number of aliases does not exceed the maximum + # of connections allowed in the specific relation. + relation_connection_limit = self.charm.meta.requires[relation_name].limit + if len(relations_aliases) != relation_connection_limit: + raise ValueError( + f"The number of aliases must match the maximum number of connections allowed in the relation. " + f"Expected {relation_connection_limit}, got {len(relations_aliases)}" + ) + + for relation_alias in relations_aliases: + self.on.define_event(f"{relation_alias}_database_created", DatabaseCreatedEvent) + self.on.define_event( + f"{relation_alias}_endpoints_changed", DatabaseEndpointsChangedEvent + ) + self.on.define_event( + f"{relation_alias}_read_only_endpoints_changed", + DatabaseReadOnlyEndpointsChangedEvent, + ) + + def _assign_relation_alias(self, relation_id: int) -> None: + """Assigns an alias to a relation. + + This function writes in the unit data bag. + + Args: + relation_id: the identifier for a particular relation. + """ + # If no aliases were provided, return immediately. + if not self.relations_aliases: + return + + # Return if an alias was already assigned to this relation + # (like when there are more than one unit joining the relation). + if ( + self.charm.model.get_relation(self.relation_name, relation_id) + .data[self.local_unit] + .get("alias") + ): + return + + # Retrieve the available aliases (the ones that weren't assigned to any relation). + available_aliases = self.relations_aliases[:] + for relation in self.charm.model.relations[self.relation_name]: + alias = relation.data[self.local_unit].get("alias") + if alias: + logger.debug("Alias %s was already assigned to relation %d", alias, relation.id) + available_aliases.remove(alias) + + # Set the alias in the unit relation databag of the specific relation. + relation = self.charm.model.get_relation(self.relation_name, relation_id) + relation.data[self.local_unit].update({"alias": available_aliases[0]}) + + def _diff(self, event: RelationChangedEvent) -> Diff: + """Retrieves the diff of the data in the relation changed databag. + + Args: + event: relation changed event. + + Returns: + a Diff instance containing the added, deleted and changed + keys from the event relation databag. + """ + # Retrieve the old data from the data key in the local unit relation databag. + old_data = json.loads(event.relation.data[self.local_unit].get("data", "{}")) + # Retrieve the new data from the event relation databag. + new_data = { + key: value for key, value in event.relation.data[event.app].items() if key != "data" + } + + # These are the keys that were added to the databag and triggered this event. + added = new_data.keys() - old_data.keys() + # These are the keys that were removed from the databag and triggered this event. + deleted = old_data.keys() - new_data.keys() + # These are the keys that already existed in the databag, + # but had their values changed. + changed = { + key for key in old_data.keys() & new_data.keys() if old_data[key] != new_data[key] + } + + # TODO: evaluate the possibility of losing the diff if some error + # happens in the charm before the diff is completely checked (DPE-412). + # Convert the new_data to a serializable format and save it for a next diff check. + event.relation.data[self.local_unit].update({"data": json.dumps(new_data)}) + + # Return the diff with all possible changes. + return Diff(added, changed, deleted) + + def _emit_aliased_event(self, event: RelationChangedEvent, event_name: str) -> None: + """Emit an aliased event to a particular relation if it has an alias. + + Args: + event: the relation changed event that was received. + event_name: the name of the event to emit. + """ + alias = self._get_relation_alias(event.relation.id) + if alias: + getattr(self.on, f"{alias}_{event_name}").emit( + event.relation, app=event.app, unit=event.unit + ) + + def _get_relation_alias(self, relation_id: int) -> Optional[str]: + """Returns the relation alias. + + Args: + relation_id: the identifier for a particular relation. + + Returns: + the relation alias or None if the relation was not found. + """ + for relation in self.charm.model.relations[self.relation_name]: + if relation.id == relation_id: + return relation.data[self.local_unit].get("alias") + return None + + def fetch_relation_data(self) -> dict: + """Retrieves data from relation. + + This function can be used to retrieve data from a relation + in the charm code when outside an event callback. + + Returns: + a dict of the values stored in the relation data bag + for all relation instances (indexed by the relation ID). + """ + data = {} + for relation in self.relations: + data[relation.id] = { + key: value for key, value in relation.data[relation.app].items() if key != "data" + } + return data + + def _update_relation_data(self, relation_id: int, data: dict) -> None: + """Updates a set of key-value pairs in the relation. + + This function writes in the application data bag, therefore, + only the leader unit can call it. + + Args: + relation_id: the identifier for a particular relation. + data: dict containing the key-value pairs + that should be updated in the relation. + """ + if self.local_unit.is_leader(): + relation = self.charm.model.get_relation(self.relation_name, relation_id) + relation.data[self.local_app].update(data) + + def _on_relation_joined_event(self, event: RelationJoinedEvent) -> None: + """Event emitted when the application joins the database relation.""" + # If relations aliases were provided, assign one to the relation. + self._assign_relation_alias(event.relation.id) + + # Sets both database and extra user roles in the relation + # if the roles are provided. Otherwise, sets only the database. + if self.extra_user_roles: + self._update_relation_data( + event.relation.id, + { + "database": self.database, + "extra-user-roles": self.extra_user_roles, + }, + ) + else: + self._update_relation_data(event.relation.id, {"database": self.database}) + + def _on_relation_changed_event(self, event: RelationChangedEvent) -> None: + """Event emitted when the database relation has changed.""" + # Check which data has changed to emit customs events. + diff = self._diff(event) + + # Check if the database is created + # (the database charm shared the credentials). + if "username" in diff.added and "password" in diff.added: + # Emit the default event (the one without an alias). + logger.info("database created at %s", datetime.now()) + self.on.database_created.emit(event.relation, app=event.app, unit=event.unit) + + # Emit the aliased event (if any). + self._emit_aliased_event(event, "database_created") + + # To avoid unnecessary application restarts do not trigger + # “endpoints_changed“ event if “database_created“ is triggered. + return + + # Emit an endpoints changed event if the database + # added or changed this info in the relation databag. + if "endpoints" in diff.added or "endpoints" in diff.changed: + # Emit the default event (the one without an alias). + logger.info("endpoints changed on %s", datetime.now()) + self.on.endpoints_changed.emit(event.relation, app=event.app, unit=event.unit) + + # Emit the aliased event (if any). + self._emit_aliased_event(event, "endpoints_changed") + + # To avoid unnecessary application restarts do not trigger + # “read_only_endpoints_changed“ event if “endpoints_changed“ is triggered. + return + + # Emit a read only endpoints changed event if the database + # added or changed this info in the relation databag. + if "read-only-endpoints" in diff.added or "read-only-endpoints" in diff.changed: + # Emit the default event (the one without an alias). + logger.info("read-only-endpoints changed on %s", datetime.now()) + self.on.read_only_endpoints_changed.emit( + event.relation, app=event.app, unit=event.unit + ) + + # Emit the aliased event (if any). + self._emit_aliased_event(event, "read_only_endpoints_changed") + + @property + def relations(self) -> List[Relation]: + """The list of Relation instances associated with this relation_name.""" + return list(self.charm.model.relations[self.relation_name]) diff --git a/charms/jimm-k8s/lib/charms/grafana_k8s/v0/grafana_dashboard.py b/charms/jimm-k8s/lib/charms/grafana_k8s/v0/grafana_dashboard.py new file mode 100644 index 000000000..1b312d709 --- /dev/null +++ b/charms/jimm-k8s/lib/charms/grafana_k8s/v0/grafana_dashboard.py @@ -0,0 +1,2012 @@ +# Copyright 2021 Canonical Ltd. +# See LICENSE file for licensing details. + +"""## Overview. + +This document explains how to integrate with the Grafana charm +for the purpose of providing a dashboard which can be used by +end users. It also explains the structure of the data +expected by the `grafana-dashboard` interface, and may provide a +mechanism or reference point for providing a compatible interface +or library by providing a definitive reference guide to the +structure of relation data which is shared between the Grafana +charm and any charm providing datasource information. + +## Provider Library Usage + +The Grafana charm interacts with its dashboards using its charm +library. The goal of this library is to be as simple to use as +possible, and instantiation of the class with or without changing +the default arguments provides a complete use case. For the simplest +use case of a charm which bundles dashboards and provides a +`provides: grafana-dashboard` interface, + + requires: + grafana-dashboard: + interface: grafana_dashboard + +creation of a `GrafanaDashboardProvider` object with the default arguments is +sufficient. + +:class:`GrafanaDashboardProvider` expects that bundled dashboards should +be included in your charm with a default path of: + + path/to/charm.py + path/to/src/grafana_dashboards/*.{json|json.tmpl|.tmpl} + +Where the files are Grafana dashboard JSON data either from the +Grafana marketplace, or directly exported from a Grafana instance. +Refer to the [official docs](https://grafana.com/tutorials/provision-dashboards-and-data-sources/) +for more information. + +When constructing a dashboard that is intended to be consumed by COS, make sure to use variables +for your datasources, and name them "prometheusds" and "lokids". You can also use the following +juju topology variables in your dashboards: $juju_model, $juju_model_uuid, $juju_application +and $juju_unit. Note, however, that if metrics are coming via peripheral charms (scrape-config +or cos-config) then topology labels would not exist. + +The default constructor arguments are: + + `charm`: `self` from the charm instantiating this library + `relation_name`: grafana-dashboard + `dashboards_path`: "/src/grafana_dashboards" + +If your configuration requires any changes from these defaults, they +may be set from the class constructor. It may be instantiated as +follows: + + from charms.grafana_k8s.v0.grafana_dashboard import GrafanaDashboardProvider + + class FooCharm: + def __init__(self, *args): + super().__init__(*args, **kwargs) + ... + self.grafana_dashboard_provider = GrafanaDashboardProvider(self) + ... + +The first argument (`self`) should be a reference to the parent (providing +dashboards), as this charm's lifecycle events will be used to re-submit +dashboard information if a charm is upgraded, the pod is restarted, or other. + +An instantiated `GrafanaDashboardProvider` validates that the path specified +in the constructor (or the default) exists, reads the file contents, then +compresses them with LZMA and adds them to the application relation data +when a relation is established with Grafana. + +Provided dashboards will be checked by Grafana, and a series of dropdown menus +providing the ability to select query targets by Juju Model, application instance, +and unit will be added if they do not exist. + +To avoid requiring `jinja` in `GrafanaDashboardProvider` users, template validation +and rendering occurs on the other side of the relation, and relation data in +the form of: + + { + "event": { + "valid": `true|false`, + "errors": [], + } + } + +Will be returned if rendering or validation fails. In this case, the +`GrafanaDashboardProvider` object will emit a `dashboard_status_changed` event +of the type :class:`GrafanaDashboardEvent`, which will contain information +about the validation error. + +This information is added to the relation data for the charms as serialized JSON +from a dict, with a structure of: +``` +{ + "application": { + "dashboards": { + "uuid": a uuid generated to ensure a relation event triggers, + "templates": { + "file:{hash}": { + "content": `{compressed_template_data}`, + "charm": `charm.meta.name`, + "juju_topology": { + "model": `charm.model.name`, + "model_uuid": `charm.model.uuid`, + "application": `charm.app.name`, + "unit": `charm.unit.name`, + } + }, + "file:{other_file_hash}": { + ... + }, + }, + }, + }, +} +``` + +This is ingested by :class:`GrafanaDashboardConsumer`, and is sufficient for configuration. + +The [COS Configuration Charm](https://charmhub.io/cos-configuration-k8s) can be used to +add dashboards which are not bundled with charms. + +## Consumer Library Usage + +The `GrafanaDashboardConsumer` object may be used by Grafana +charms to manage relations with available dashboards. For this +purpose, a charm consuming Grafana dashboard information should do +the following things: + +1. Instantiate the `GrafanaDashboardConsumer` object by providing it a +reference to the parent (Grafana) charm and, optionally, the name of +the relation that the Grafana charm uses to interact with dashboards. +This relation must confirm to the `grafana-dashboard` interface. + +For example a Grafana charm may instantiate the +`GrafanaDashboardConsumer` in its constructor as follows + + from charms.grafana_k8s.v0.grafana_dashboard import GrafanaDashboardConsumer + + def __init__(self, *args): + super().__init__(*args) + ... + self.grafana_dashboard_consumer = GrafanaDashboardConsumer(self) + ... + +2. A Grafana charm also needs to listen to the +`GrafanaDashboardConsumer` events emitted by the `GrafanaDashboardConsumer` +by adding itself as an observer for these events: + + self.framework.observe( + self.grafana_source_consumer.on.sources_changed, + self._on_dashboards_changed, + ) + +Dashboards can be retrieved the :meth:`dashboards`: + +It will be returned in the format of: + +``` +[ + { + "id": unique_id, + "relation_id": relation_id, + "charm": the name of the charm which provided the dashboard, + "content": compressed_template_data + }, +] +``` + +The consuming charm should decompress the dashboard. +""" + +import base64 +import hashlib +import json +import logging +import lzma +import os +import platform +import re +import subprocess +import tempfile +import uuid +from pathlib import Path +from typing import Any, Dict, List, Optional, Tuple, Union + +import yaml +from ops.charm import ( + CharmBase, + HookEvent, + RelationBrokenEvent, + RelationChangedEvent, + RelationCreatedEvent, + RelationEvent, + RelationRole, +) +from ops.framework import ( + EventBase, + EventSource, + Object, + ObjectEvents, + StoredDict, + StoredList, + StoredState, +) +from ops.model import Relation + +# The unique Charmhub library identifier, never change it +LIBID = "c49eb9c7dfef40c7b6235ebd67010a3f" + +# Increment this major API version when introducing breaking changes +LIBAPI = 0 + +# Increment this PATCH version before using `charmcraft publish-lib` or reset +# to 0 if you are raising the major API version + +LIBPATCH = 31 + +logger = logging.getLogger(__name__) + + +DEFAULT_RELATION_NAME = "grafana-dashboard" +DEFAULT_PEER_NAME = "grafana" +RELATION_INTERFACE_NAME = "grafana_dashboard" + +TOPOLOGY_TEMPLATE_DROPDOWNS = [ # type: ignore + { + "allValue": ".*", + "datasource": "${prometheusds}", + "definition": "label_values(up,juju_model)", + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "Juju model", + "multi": True, + "name": "juju_model", + "query": { + "query": "label_values(up,juju_model)", + "refId": "StandardVariableQuery", + }, + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "sort": 0, + "tagValuesQuery": "", + "tags": [], + "tagsQuery": "", + "type": "query", + "useTags": False, + }, + { + "allValue": ".*", + "datasource": "${prometheusds}", + "definition": 'label_values(up{juju_model=~"$juju_model"},juju_model_uuid)', + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "Juju model uuid", + "multi": True, + "name": "juju_model_uuid", + "query": { + "query": 'label_values(up{juju_model=~"$juju_model"},juju_model_uuid)', + "refId": "StandardVariableQuery", + }, + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "sort": 0, + "tagValuesQuery": "", + "tags": [], + "tagsQuery": "", + "type": "query", + "useTags": False, + }, + { + "allValue": ".*", + "datasource": "${prometheusds}", + "definition": 'label_values(up{juju_model=~"$juju_model",juju_model_uuid=~"$juju_model_uuid"},juju_application)', + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "Juju application", + "multi": True, + "name": "juju_application", + "query": { + "query": 'label_values(up{juju_model=~"$juju_model",juju_model_uuid=~"$juju_model_uuid"},juju_application)', + "refId": "StandardVariableQuery", + }, + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "sort": 0, + "tagValuesQuery": "", + "tags": [], + "tagsQuery": "", + "type": "query", + "useTags": False, + }, + { + "allValue": ".*", + "datasource": "${prometheusds}", + "definition": 'label_values(up{juju_model=~"$juju_model",juju_model_uuid=~"$juju_model_uuid",juju_application=~"$juju_application"},juju_unit)', + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "Juju unit", + "multi": True, + "name": "juju_unit", + "query": { + "query": 'label_values(up{juju_model=~"$juju_model",juju_model_uuid=~"$juju_model_uuid",juju_application=~"$juju_application"},juju_unit)', + "refId": "StandardVariableQuery", + }, + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "sort": 0, + "tagValuesQuery": "", + "tags": [], + "tagsQuery": "", + "type": "query", + "useTags": False, + }, +] + +DATASOURCE_TEMPLATE_DROPDOWNS = [ # type: ignore + { + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "Prometheus datasource", + "multi": True, + "name": "prometheusds", + "options": [], + "query": "prometheus", + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "type": "datasource", + }, + { + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "Loki datasource", + "multi": True, + "name": "lokids", + "options": [], + "query": "loki", + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "type": "datasource", + }, +] + +REACTIVE_CONVERTER = { # type: ignore + "allValue": None, + "datasource": "${prometheusds}", + "definition": 'label_values(up{juju_model=~"$juju_model",juju_model_uuid=~"$juju_model_uuid",juju_application=~"$juju_application"},host)', + "description": None, + "error": None, + "hide": 0, + "includeAll": True, + "label": "hosts", + "multi": True, + "name": "host", + "options": [], + "query": { + "query": 'label_values(up{juju_model=~"$juju_model",juju_model_uuid=~"$juju_model_uuid",juju_application=~"$juju_application"},host)', + "refId": "StandardVariableQuery", + }, + "refresh": 1, + "regex": "", + "skipUrlSync": False, + "sort": 1, + "tagValuesQuery": "", + "tags": [], + "tagsQuery": "", + "type": "query", + "useTags": False, +} + + +class RelationNotFoundError(Exception): + """Raised if there is no relation with the given name.""" + + def __init__(self, relation_name: str): + self.relation_name = relation_name + self.message = "No relation named '{}' found".format(relation_name) + + super().__init__(self.message) + + +class RelationInterfaceMismatchError(Exception): + """Raised if the relation with the given name has a different interface.""" + + def __init__( + self, + relation_name: str, + expected_relation_interface: str, + actual_relation_interface: str, + ): + self.relation_name = relation_name + self.expected_relation_interface = expected_relation_interface + self.actual_relation_interface = actual_relation_interface + self.message = ( + "The '{}' relation has '{}' as " + "interface rather than the expected '{}'".format( + relation_name, actual_relation_interface, expected_relation_interface + ) + ) + + super().__init__(self.message) + + +class RelationRoleMismatchError(Exception): + """Raised if the relation with the given name has a different direction.""" + + def __init__( + self, + relation_name: str, + expected_relation_role: RelationRole, + actual_relation_role: RelationRole, + ): + self.relation_name = relation_name + self.expected_relation_interface = expected_relation_role + self.actual_relation_role = actual_relation_role + self.message = "The '{}' relation has role '{}' rather than the expected '{}'".format( + relation_name, repr(actual_relation_role), repr(expected_relation_role) + ) + + super().__init__(self.message) + + +class InvalidDirectoryPathError(Exception): + """Raised if the grafana dashboards folder cannot be found or is otherwise invalid.""" + + def __init__( + self, + grafana_dashboards_absolute_path: str, + message: str, + ): + self.grafana_dashboards_absolute_path = grafana_dashboards_absolute_path + self.message = message + + super().__init__(self.message) + + +def _resolve_dir_against_charm_path(charm: CharmBase, *path_elements: str) -> str: + """Resolve the provided path items against the directory of the main file. + + Look up the directory of the charmed operator file being executed. This is normally + going to be the charm.py file of the charm including this library. Then, resolve + the provided path elements and return its absolute path. + + Raises: + InvalidDirectoryPathError if the resolved path does not exist or it is not a directory + + """ + charm_dir = Path(str(charm.charm_dir)) + if not charm_dir.exists() or not charm_dir.is_dir(): + # Operator Framework does not currently expose a robust + # way to determine the top level charm source directory + # that is consistent across deployed charms and unit tests + # Hence for unit tests the current working directory is used + # TODO: updated this logic when the following ticket is resolved + # https://github.com/canonical/operator/issues/643 + charm_dir = Path(os.getcwd()) + + dir_path = charm_dir.absolute().joinpath(*path_elements) + + if not dir_path.exists(): + raise InvalidDirectoryPathError(str(dir_path), "directory does not exist") + if not dir_path.is_dir(): + raise InvalidDirectoryPathError(str(dir_path), "is not a directory") + + return str(dir_path) + + +def _validate_relation_by_interface_and_direction( + charm: CharmBase, + relation_name: str, + expected_relation_interface: str, + expected_relation_role: RelationRole, +) -> None: + """Verifies that a relation has the necessary characteristics. + + Verifies that the `relation_name` provided: (1) exists in metadata.yaml, + (2) declares as interface the interface name passed as `relation_interface` + and (3) has the right "direction", i.e., it is a relation that `charm` + provides or requires. + + Args: + charm: a `CharmBase` object to scan for the matching relation. + relation_name: the name of the relation to be verified. + expected_relation_interface: the interface name to be matched by the + relation named `relation_name`. + expected_relation_role: whether the `relation_name` must be either + provided or required by `charm`. + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + named like the value of the `relation_name` argument. + RelationInterfaceMismatchError: If the relation interface of the + relation named as the provided `relation_name` argument does not + match the `expected_relation_interface` argument. + RelationRoleMismatchError: If the relation named as the provided `relation_name` + argument has a different role than what is specified by the + `expected_relation_role` argument. + """ + if relation_name not in charm.meta.relations: + raise RelationNotFoundError(relation_name) + + relation = charm.meta.relations[relation_name] + + actual_relation_interface = relation.interface_name + if actual_relation_interface != expected_relation_interface: + raise RelationInterfaceMismatchError( + relation_name, expected_relation_interface, actual_relation_interface + ) + + if expected_relation_role == RelationRole.provides: + if relation_name not in charm.meta.provides: + raise RelationRoleMismatchError( + relation_name, RelationRole.provides, RelationRole.requires + ) + elif expected_relation_role == RelationRole.requires: + if relation_name not in charm.meta.requires: + raise RelationRoleMismatchError( + relation_name, RelationRole.requires, RelationRole.provides + ) + else: + raise Exception("Unexpected RelationDirection: {}".format(expected_relation_role)) + + +def _encode_dashboard_content(content: Union[str, bytes]) -> str: + if isinstance(content, str): + content = bytes(content, "utf-8") + + return base64.b64encode(lzma.compress(content)).decode("utf-8") + + +def _decode_dashboard_content(encoded_content: str) -> str: + return lzma.decompress(base64.b64decode(encoded_content.encode("utf-8"))).decode() + + +def _convert_dashboard_fields(content: str, inject_dropdowns: bool = True) -> str: + """Make sure values are present for Juju topology. + + Inserts Juju topology variables and selectors into the template, as well as + a variable for Prometheus. + """ + dict_content = json.loads(content) + datasources = {} + existing_templates = False + + template_dropdowns = ( + TOPOLOGY_TEMPLATE_DROPDOWNS + DATASOURCE_TEMPLATE_DROPDOWNS # type: ignore + if inject_dropdowns + else DATASOURCE_TEMPLATE_DROPDOWNS + ) + + # If the dashboard has __inputs, get the names to replace them. These are stripped + # from reactive dashboards in GrafanaDashboardAggregator, but charm authors in + # newer charms may import them directly from the marketplace + if "__inputs" in dict_content: + for field in dict_content["__inputs"]: + if "type" in field and field["type"] == "datasource": + datasources[field["name"]] = field["pluginName"].lower() + del dict_content["__inputs"] + + # If no existing template variables exist, just insert our own + if "templating" not in dict_content: + dict_content["templating"] = {"list": list(template_dropdowns)} # type: ignore + else: + # Otherwise, set a flag so we can go back later + existing_templates = True + for template_value in dict_content["templating"]["list"]: + # Build a list of `datasource_name`: `datasource_type` mappings + # The "query" field is actually "prometheus", "loki", "influxdb", etc + if "type" in template_value and template_value["type"] == "datasource": + datasources[template_value["name"]] = template_value["query"].lower() + + # Put our own variables in the template + for d in template_dropdowns: # type: ignore + if d not in dict_content["templating"]["list"]: + dict_content["templating"]["list"].insert(0, d) + + dict_content = _replace_template_fields(dict_content, datasources, existing_templates) + return json.dumps(dict_content) + + +def _replace_template_fields( # noqa: C901 + dict_content: dict, datasources: dict, existing_templates: bool +) -> dict: + """Make templated fields get cleaned up afterwards. + + If existing datasource variables are present, try to substitute them. + """ + replacements = {"loki": "${lokids}", "prometheus": "${prometheusds}"} + used_replacements = [] # type: List[str] + + # If any existing datasources match types we know, or we didn't find + # any templating variables at all, template them. + if datasources or not existing_templates: + panels = dict_content.get("panels", {}) + if panels: + dict_content["panels"] = _template_panels( + panels, replacements, used_replacements, existing_templates, datasources + ) + + # Find panels nested under rows + rows = dict_content.get("rows", {}) + if rows: + for row_idx, row in enumerate(rows): + if "panels" in row.keys(): + rows[row_idx]["panels"] = _template_panels( + row["panels"], + replacements, + used_replacements, + existing_templates, + datasources, + ) + + dict_content["rows"] = rows + + # Finally, go back and pop off the templates we stubbed out + deletions = [] + for tmpl in dict_content["templating"]["list"]: + if tmpl["name"] and tmpl["name"] in used_replacements: + deletions.append(tmpl) + + for d in deletions: + dict_content["templating"]["list"].remove(d) + + return dict_content + + +def _template_panels( + panels: dict, + replacements: dict, + used_replacements: list, + existing_templates: bool, + datasources: dict, +) -> dict: + """Iterate through a `panels` object and template it appropriately.""" + # Go through all the panels. If they have a datasource set, AND it's one + # that we can convert to ${lokids} or ${prometheusds}, by stripping off the + # ${} templating and comparing the name to the list we built, replace it, + # otherwise, leave it alone. + # + for panel in panels: + if "datasource" not in panel or not panel.get("datasource"): + continue + if not existing_templates: + datasource = panel.get("datasource") + if type(datasource) == str: + if "loki" in datasource: + panel["datasource"] = "${lokids}" + elif "grafana" in datasource: + continue + else: + panel["datasource"] = "${prometheusds}" + elif type(datasource) == dict: + # In dashboards exported by Grafana 9, datasource type is dict + dstype = datasource.get("type", "") + if dstype == "loki": + panel["datasource"]["uid"] = "${lokids}" + elif dstype == "prometheus": + panel["datasource"]["uid"] = "${prometheusds}" + else: + logger.debug("Unrecognized datasource type '%s'; skipping", dstype) + continue + else: + logger.error("Unknown datasource format: skipping") + continue + else: + if type(panel["datasource"]) == str: + if panel["datasource"].lower() in replacements.values(): + # Already a known template variable + continue + # Strip out variable characters and maybe braces + ds = re.sub(r"(\$|\{|\})", "", panel["datasource"]) + + if ds not in datasources.keys(): + # Unknown, non-templated datasource, potentially a Grafana builtin + continue + + replacement = replacements.get(datasources[ds], "") + if replacement: + used_replacements.append(ds) + panel["datasource"] = replacement or panel["datasource"] + elif type(panel["datasource"]) == dict: + dstype = panel["datasource"].get("type", "") + if panel["datasource"].get("uid", "").lower() in replacements.values(): + # Already a known template variable + continue + # Strip out variable characters and maybe braces + ds = re.sub(r"(\$|\{|\})", "", panel["datasource"].get("uid", "")) + + if ds not in datasources.keys(): + # Unknown, non-templated datasource, potentially a Grafana builtin + continue + + replacement = replacements.get(datasources[ds], "") + if replacement: + used_replacements.append(ds) + panel["datasource"]["uid"] = replacement + else: + logger.error("Unknown datasource format: skipping") + continue + return panels + + +def _inject_labels(content: str, topology: dict, transformer: "CosTool") -> str: + """Inject Juju topology into panel expressions via CosTool. + + A dashboard will have a structure approximating: + { + "__inputs": [], + "templating": { + "list": [ + { + "name": "prometheusds", + "type": "prometheus" + } + ] + }, + "panels": [ + { + "foo": "bar", + "targets": [ + { + "some": "field", + "expr": "up{job="foo"}" + }, + { + "some_other": "field", + "expr": "sum(http_requests_total{instance="$foo"}[5m])} + } + ], + "datasource": "${someds}" + } + ] + } + + `templating` is used elsewhere in this library, but the structure is not rigid. It is + not guaranteed that a panel will actually have any targets (it could be a "spacer" with + no datasource, hence no expression). It could have only one target. It could have multiple + targets. It could have multiple targets of which only one has an `expr` to evaluate. We need + to try to handle all of these concisely. + + `cos-tool` (`github.com/canonical/cos-tool` as a Go module in general) + does not know "Grafana-isms", such as using `[$_variable]` to modify the query from the user + interface, so we add placeholders (as `5y`, since it must parse, but a dashboard looking for + five years for a panel query would be unusual). + + Args: + content: dashboard content as a string + topology: a dict containing topology values + transformer: a 'CosTool' instance + Returns: + dashboard content with replaced values. + """ + dict_content = json.loads(content) + + if "panels" not in dict_content.keys(): + return json.dumps(dict_content) + + # Go through all the panels and inject topology labels + # Panels may have more than one 'target' where the expressions live, so that must be + # accounted for. Additionally, `promql-transform` does not necessarily gracefully handle + # expressions with range queries including variables. Exclude these. + # + # It is not a certainty that the `datasource` field will necessarily reflect the type, so + # operate on all fields. + panels = dict_content["panels"] + topology_with_prefix = {"juju_{}".format(k): v for k, v in topology.items()} + + # We need to use an index so we can insert the changed element back later + for panel_idx, panel in enumerate(panels): + if type(panel) is not dict: + continue + + # Use the index to insert it back in the same location + panels[panel_idx] = _modify_panel(panel, topology_with_prefix, transformer) + + return json.dumps(dict_content) + + +def _modify_panel(panel: dict, topology: dict, transformer: "CosTool") -> dict: + """Inject Juju topology into panel expressions via CosTool. + + Args: + panel: a dashboard panel as a dict + topology: a dict containing topology values + transformer: a 'CosTool' instance + Returns: + the panel with injected values + """ + if "targets" not in panel.keys(): + return panel + + # Pre-compile a regular expression to grab values from inside of [] + range_re = re.compile(r"\[(?P.*?)\]") + # Do the same for any offsets + offset_re = re.compile(r"offset\s+(?P-?\s*[$\w]+)") + + known_datasources = {"${prometheusds}": "promql", "${lokids}": "logql"} + + targets = panel["targets"] + + # We need to use an index so we can insert the changed element back later + for idx, target in enumerate(targets): + # If there's no expression, we don't need to do anything + if "expr" not in target.keys(): + continue + expr = target["expr"] + + if "datasource" not in panel.keys(): + continue + + if type(panel["datasource"]) == str: + if panel["datasource"] not in known_datasources: + continue + querytype = known_datasources[panel["datasource"]] + elif type(panel["datasource"]) == dict: + if panel["datasource"]["uid"] not in known_datasources: + continue + querytype = known_datasources[panel["datasource"]["uid"]] + else: + logger.error("Unknown datasource format: skipping") + continue + + # Capture all values inside `[]` into a list which we'll iterate over later to + # put them back in-order. Then apply the regex again and replace everything with + # `[5y]` so promql/parser will take it. + # + # Then do it again for offsets + range_values = [m.group("value") for m in range_re.finditer(expr)] + expr = range_re.sub(r"[5y]", expr) + + offset_values = [m.group("value") for m in offset_re.finditer(expr)] + expr = offset_re.sub(r"offset 5y", expr) + # Retrieve the new expression (which may be unchanged if there were no label + # matchers in the expression, or if tt was unable to be parsed like logql. It's + # virtually impossible to tell from any datasource "name" in a panel what the + # actual type is without re-implementing a complete dashboard parser, but no + # harm will some from passing invalid promql -- we'll just get the original back. + # + replacement = transformer.inject_label_matchers(expr, topology, querytype) + + if replacement == target["expr"]: + # promql-tranform caught an error. Move on + continue + + # Go back and substitute values in [] which were pulled out + # Enumerate with an index... again. The same regex is ok, since it will still match + # `[(.*?)]`, which includes `[5y]`, our placeholder + for i, match in enumerate(range_re.finditer(replacement)): + # Replace one-by-one, starting from the left. We build the string back with + # `str.replace(string_to_replace, replacement_value, count)`. Limit the count + # to one, since we are going through one-by-one through the list we saved earlier + # in `range_values`. + replacement = replacement.replace( + "[{}]".format(match.group("value")), + "[{}]".format(range_values[i]), + 1, + ) + + for i, match in enumerate(offset_re.finditer(replacement)): + # Replace one-by-one, starting from the left. We build the string back with + # `str.replace(string_to_replace, replacement_value, count)`. Limit the count + # to one, since we are going through one-by-one through the list we saved earlier + # in `range_values`. + replacement = replacement.replace( + "offset {}".format(match.group("value")), + "offset {}".format(offset_values[i]), + 1, + ) + + # Use the index to insert it back in the same location + targets[idx]["expr"] = replacement + + panel["targets"] = targets + return panel + + +def _type_convert_stored(obj): + """Convert Stored* to their appropriate types, recursively.""" + if isinstance(obj, StoredList): + return list(map(_type_convert_stored, obj)) + if isinstance(obj, StoredDict): + rdict = {} # type: Dict[Any, Any] + for k in obj.keys(): + rdict[k] = _type_convert_stored(obj[k]) + return rdict + return obj + + +class GrafanaDashboardsChanged(EventBase): + """Event emitted when Grafana dashboards change.""" + + def __init__(self, handle, data=None): + super().__init__(handle) + self.data = data + + def snapshot(self) -> Dict: + """Save grafana source information.""" + return {"data": self.data} + + def restore(self, snapshot): + """Restore grafana source information.""" + self.data = snapshot["data"] + + +class GrafanaDashboardEvents(ObjectEvents): + """Events raised by :class:`GrafanaSourceEvents`.""" + + dashboards_changed = EventSource(GrafanaDashboardsChanged) + + +class GrafanaDashboardEvent(EventBase): + """Event emitted when Grafana dashboards cannot be resolved. + + Enables us to set a clear status on the provider. + """ + + def __init__(self, handle, errors: List[Dict[str, str]] = [], valid: bool = False): + super().__init__(handle) + self.errors = errors + self.error_message = "; ".join([error["error"] for error in errors if "error" in error]) + self.valid = valid + + def snapshot(self) -> Dict: + """Save grafana source information.""" + return { + "error_message": self.error_message, + "valid": self.valid, + "errors": json.dumps(self.errors), + } + + def restore(self, snapshot): + """Restore grafana source information.""" + self.error_message = snapshot["error_message"] + self.valid = snapshot["valid"] + self.errors = json.loads(str(snapshot["errors"])) + + +class GrafanaProviderEvents(ObjectEvents): + """Events raised by :class:`GrafanaSourceEvents`.""" + + dashboard_status_changed = EventSource(GrafanaDashboardEvent) + + +class GrafanaDashboardProvider(Object): + """An API to provide Grafana dashboards to a Grafana charm.""" + + _stored = StoredState() + on = GrafanaProviderEvents() # pyright: ignore + + def __init__( + self, + charm: CharmBase, + relation_name: str = DEFAULT_RELATION_NAME, + dashboards_path: str = "src/grafana_dashboards", + ) -> None: + """API to provide Grafana dashboard to a Grafana charmed operator. + + The :class:`GrafanaDashboardProvider` object provides an API + to upload dashboards to a Grafana charm. In its most streamlined + usage, the :class:`GrafanaDashboardProvider` is integrated in a + charmed operator as follows: + + self.grafana = GrafanaDashboardProvider(self) + + The :class:`GrafanaDashboardProvider` will look for dashboard + templates in the `/grafana_dashboards` folder. + Additionally, dashboard templates can be uploaded programmatically + via the :method:`GrafanaDashboardProvider.add_dashboard` method. + + To use the :class:`GrafanaDashboardProvider` API, you need a relation + defined in your charm operator's metadata.yaml as follows: + + provides: + grafana-dashboard: + interface: grafana_dashboard + + If you would like to use relation name other than `grafana-dashboard`, + you will need to specify the relation name via the `relation_name` + argument when instantiating the :class:`GrafanaDashboardProvider` object. + However, it is strongly advised to keep the default relation name, + so that people deploying your charm will have a consistent experience + with all other charms that provide Grafana dashboards. + + It is possible to provide a different file path for the Grafana dashboards + to be automatically managed by the :class:`GrafanaDashboardProvider` object + via the `dashboards_path` argument. This may be necessary when the directory + structure of your charmed operator repository is not the "usual" one as + generated by `charmcraft init`, for example when adding the charmed operator + in a Java repository managed by Maven or Gradle. However, unless there are + such constraints with other tooling, it is strongly advised to store the + Grafana dashboards in the default `/grafana_dashboards` + folder, in order to provide a consistent experience for other charmed operator + authors. + + Args: + charm: a :class:`CharmBase` object which manages this + :class:`GrafanaProvider` object. Generally this is + `self` in the instantiating class. + relation_name: a :string: name of the relation managed by this + :class:`GrafanaDashboardProvider`; it defaults to "grafana-dashboard". + dashboards_path: a filesystem path relative to the charm root + where dashboard templates can be located. By default, the library + expects dashboard files to be in the `/grafana_dashboards` + directory. + """ + _validate_relation_by_interface_and_direction( + charm, relation_name, RELATION_INTERFACE_NAME, RelationRole.provides + ) + + try: + dashboards_path = _resolve_dir_against_charm_path(charm, dashboards_path) + except InvalidDirectoryPathError as e: + logger.warning( + "Invalid Grafana dashboards folder at %s: %s", + e.grafana_dashboards_absolute_path, + e.message, + ) + + super().__init__(charm, relation_name) + + self._charm = charm + self._relation_name = relation_name + self._dashboards_path = dashboards_path + + # No peer relation bucket we can rely on providers, keep StoredState here, too + self._stored.set_default(dashboard_templates={}) # type: ignore + + self.framework.observe(self._charm.on.leader_elected, self._update_all_dashboards_from_dir) + self.framework.observe(self._charm.on.upgrade_charm, self._update_all_dashboards_from_dir) + + self.framework.observe( + self._charm.on[self._relation_name].relation_created, + self._on_grafana_dashboard_relation_created, + ) + self.framework.observe( + self._charm.on[self._relation_name].relation_changed, + self._on_grafana_dashboard_relation_changed, + ) + + def add_dashboard(self, content: str, inject_dropdowns: bool = True) -> None: + """Add a dashboard to the relation managed by this :class:`GrafanaDashboardProvider`. + + Args: + content: a string representing a Jinja template. Currently, no + global variables are added to the Jinja template evaluation + context. + inject_dropdowns: a :boolean: indicating whether topology dropdowns should be + added to the dashboard + """ + # Update of storage must be done irrespective of leadership, so + # that the stored state is there when this unit becomes leader. + stored_dashboard_templates: Any = self._stored.dashboard_templates # pyright: ignore + + encoded_dashboard = _encode_dashboard_content(content) + + # Use as id the first chars of the encoded dashboard, so that + # it is predictable across units. + id = "prog:{}".format(encoded_dashboard[-24:-16]) + + stored_dashboard_templates[id] = self._content_to_dashboard_object( + encoded_dashboard, inject_dropdowns + ) + stored_dashboard_templates[id]["dashboard_alt_uid"] = self._generate_alt_uid(id) + + if self._charm.unit.is_leader(): + for dashboard_relation in self._charm.model.relations[self._relation_name]: + self._upset_dashboards_on_relation(dashboard_relation) + + def remove_non_builtin_dashboards(self) -> None: + """Remove all dashboards to the relation added via :method:`add_dashboard`.""" + # Update of storage must be done irrespective of leadership, so + # that the stored state is there when this unit becomes leader. + stored_dashboard_templates: Any = self._stored.dashboard_templates # pyright: ignore + + for dashboard_id in list(stored_dashboard_templates.keys()): + if dashboard_id.startswith("prog:"): + del stored_dashboard_templates[dashboard_id] + self._stored.dashboard_templates = stored_dashboard_templates + + if self._charm.unit.is_leader(): + for dashboard_relation in self._charm.model.relations[self._relation_name]: + self._upset_dashboards_on_relation(dashboard_relation) + + def update_dashboards(self) -> None: + """Trigger the re-evaluation of the data on all relations.""" + if self._charm.unit.is_leader(): + for dashboard_relation in self._charm.model.relations[self._relation_name]: + self._upset_dashboards_on_relation(dashboard_relation) + + def _update_all_dashboards_from_dir( + self, _: Optional[HookEvent] = None, inject_dropdowns: bool = True + ) -> None: + """Scans the built-in dashboards and updates relations with changes.""" + # Update of storage must be done irrespective of leadership, so + # that the stored state is there when this unit becomes leader. + + # Ensure we do not leave outdated dashboards by removing from stored all + # the encoded dashboards that start with "file/". + if self._dashboards_path: + stored_dashboard_templates: Any = self._stored.dashboard_templates # pyright: ignore + + for dashboard_id in list(stored_dashboard_templates.keys()): + if dashboard_id.startswith("file:"): + del stored_dashboard_templates[dashboard_id] + + # Path.glob uses fnmatch on the backend, which is pretty limited, so use a + # custom function for the filter + def _is_dashboard(p: Path) -> bool: + return p.is_file() and p.name.endswith((".json", ".json.tmpl", ".tmpl")) + + for path in filter(_is_dashboard, Path(self._dashboards_path).glob("*")): + # path = Path(path) + id = "file:{}".format(path.stem) + stored_dashboard_templates[id] = self._content_to_dashboard_object( + _encode_dashboard_content(path.read_bytes()), inject_dropdowns + ) + stored_dashboard_templates[id]["dashboard_alt_uid"] = self._generate_alt_uid(id) + + self._stored.dashboard_templates = stored_dashboard_templates + + if self._charm.unit.is_leader(): + for dashboard_relation in self._charm.model.relations[self._relation_name]: + self._upset_dashboards_on_relation(dashboard_relation) + + def _generate_alt_uid(self, key: str) -> str: + """Generate alternative uid for dashboards. + + Args: + key: A string used (along with charm.meta.name) to build the hash uid. + + Returns: A hash string. + """ + raw_dashboard_alt_uid = "{}-{}".format(self._charm.meta.name, key) + return hashlib.shake_256(raw_dashboard_alt_uid.encode("utf-8")).hexdigest(8) + + def _reinitialize_dashboard_data(self, inject_dropdowns: bool = True) -> None: + """Triggers a reload of dashboard outside of an eventing workflow. + + Args: + inject_dropdowns: a :bool: used to indicate whether topology dropdowns should be added + + This will destroy any existing relation data. + """ + try: + _resolve_dir_against_charm_path(self._charm, self._dashboards_path) + self._update_all_dashboards_from_dir(inject_dropdowns=inject_dropdowns) + + except InvalidDirectoryPathError as e: + logger.warning( + "Invalid Grafana dashboards folder at %s: %s", + e.grafana_dashboards_absolute_path, + e.message, + ) + stored_dashboard_templates: Any = self._stored.dashboard_templates # pyright: ignore + + for dashboard_id in list(stored_dashboard_templates.keys()): + if dashboard_id.startswith("file:"): + del stored_dashboard_templates[dashboard_id] + self._stored.dashboard_templates = stored_dashboard_templates + + # With all the file-based dashboards cleared out, force a refresh + # of relation data + if self._charm.unit.is_leader(): + for dashboard_relation in self._charm.model.relations[self._relation_name]: + self._upset_dashboards_on_relation(dashboard_relation) + + def _on_grafana_dashboard_relation_created(self, event: RelationCreatedEvent) -> None: + """Watch for a relation being created and automatically send dashboards. + + Args: + event: The :class:`RelationJoinedEvent` sent when a + `grafana_dashboaard` relationship is joined + """ + if self._charm.unit.is_leader(): + self._upset_dashboards_on_relation(event.relation) + + def _on_grafana_dashboard_relation_changed(self, event: RelationChangedEvent) -> None: + """Watch for changes so we know if there's an error to signal back to the parent charm. + + Args: + event: The `RelationChangedEvent` that triggered this handler. + """ + if self._charm.unit.is_leader(): + data = json.loads(event.relation.data[event.app].get("event", "{}")) # type: ignore + + if not data: + return + + valid = bool(data.get("valid", True)) + errors = data.get("errors", []) + if valid and not errors: + self.on.dashboard_status_changed.emit(valid=valid) # pyright: ignore + else: + self.on.dashboard_status_changed.emit( # pyright: ignore + valid=valid, errors=errors + ) + + def _upset_dashboards_on_relation(self, relation: Relation) -> None: + """Update the dashboards in the relation data bucket.""" + # It's completely ridiculous to add a UUID, but if we don't have some + # pseudo-random value, this never makes it across 'juju set-state' + stored_data = { + "templates": _type_convert_stored(self._stored.dashboard_templates), # pyright: ignore + "uuid": str(uuid.uuid4()), + } + + relation.data[self._charm.app]["dashboards"] = json.dumps(stored_data) + + def _content_to_dashboard_object(self, content: str, inject_dropdowns: bool = True) -> Dict: + return { + "charm": self._charm.meta.name, + "content": content, + "juju_topology": self._juju_topology if inject_dropdowns else {}, + "inject_dropdowns": inject_dropdowns, + } + + # This is not actually used in the dashboards, but is present to provide a secondary + # salt to ensure uniqueness in the dict keys in case individual charm units provide + # dashboards + @property + def _juju_topology(self) -> Dict: + return { + "model": self._charm.model.name, + "model_uuid": self._charm.model.uuid, + "application": self._charm.app.name, + "unit": self._charm.unit.name, + } + + @property + def dashboard_templates(self) -> List: + """Return a list of the known dashboard templates.""" + return list(self._stored.dashboard_templates.values()) # type: ignore + + +class GrafanaDashboardConsumer(Object): + """A consumer object for working with Grafana Dashboards.""" + + on = GrafanaDashboardEvents() # pyright: ignore + _stored = StoredState() + + def __init__( + self, + charm: CharmBase, + relation_name: str = DEFAULT_RELATION_NAME, + ) -> None: + """API to receive Grafana dashboards from charmed operators. + + The :class:`GrafanaDashboardConsumer` object provides an API + to consume dashboards provided by a charmed operator using the + :class:`GrafanaDashboardProvider` library. The + :class:`GrafanaDashboardConsumer` is integrated in a + charmed operator as follows: + + self.grafana = GrafanaDashboardConsumer(self) + + To use this library, you need a relation defined as follows in + your charm operator's metadata.yaml: + + requires: + grafana-dashboard: + interface: grafana_dashboard + + If you would like to use a different relation name than + `grafana-dashboard`, you need to specify the relation name via the + `relation_name` argument. However, it is strongly advised not to + change the default, so that people deploying your charm will have + a consistent experience with all other charms that consume Grafana + dashboards. + + Args: + charm: a :class:`CharmBase` object which manages this + :class:`GrafanaProvider` object. Generally this is + `self` in the instantiating class. + relation_name: a :string: name of the relation managed by this + :class:`GrafanaDashboardConsumer`; it defaults to "grafana-dashboard". + """ + _validate_relation_by_interface_and_direction( + charm, relation_name, RELATION_INTERFACE_NAME, RelationRole.requires + ) + + super().__init__(charm, relation_name) + self._charm = charm + self._relation_name = relation_name + self._tranformer = CosTool(self._charm) + + self._stored.set_default(dashboards={}) # type: ignore + + self.framework.observe( + self._charm.on[self._relation_name].relation_changed, + self._on_grafana_dashboard_relation_changed, + ) + self.framework.observe( + self._charm.on[self._relation_name].relation_broken, + self._on_grafana_dashboard_relation_broken, + ) + self.framework.observe( + self._charm.on[DEFAULT_PEER_NAME].relation_changed, + self._on_grafana_peer_changed, + ) + + def get_dashboards_from_relation(self, relation_id: int) -> List: + """Get a list of known dashboards for one instance of the monitored relation. + + Args: + relation_id: the identifier of the relation instance, as returned by + :method:`ops.model.Relation.id`. + + Returns: a list of known dashboards coming from the provided relation instance. + """ + return [ + self._to_external_object(relation_id, dashboard) + for dashboard in self._get_stored_dashboards(relation_id) + ] + + def _on_grafana_dashboard_relation_changed(self, event: RelationChangedEvent) -> None: + """Handle relation changes in related providers. + + If there are changes in relations between Grafana dashboard consumers + and providers, this event handler (if the unit is the leader) will + get data for an incoming grafana-dashboard relation through a + :class:`GrafanaDashboardsChanged` event, and make the relation data + available in the app's datastore object. The Grafana charm can + then respond to the event to update its configuration. + """ + changes = False + if self._charm.unit.is_leader(): + changes = self._render_dashboards_and_signal_changed(event.relation) + + if changes: + self.on.dashboards_changed.emit() # pyright: ignore + + def _on_grafana_peer_changed(self, _: RelationChangedEvent) -> None: + """Emit dashboard events on peer events so secondary charm data updates.""" + if self._charm.unit.is_leader(): + return + self.on.dashboards_changed.emit() # pyright: ignore + + def update_dashboards(self, relation: Optional[Relation] = None) -> None: + """Re-establish dashboards on one or more relations. + + If something changes between this library and a datasource, try to re-establish + invalid dashboards and invalidate active ones. + + Args: + relation: a specific relation for which the dashboards have to be + updated. If not specified, all relations managed by this + :class:`GrafanaDashboardConsumer` will be updated. + """ + if self._charm.unit.is_leader(): + relations = ( + [relation] if relation else self._charm.model.relations[self._relation_name] + ) + + for relation in relations: + self._render_dashboards_and_signal_changed(relation) + + def _on_grafana_dashboard_relation_broken(self, event: RelationBrokenEvent) -> None: + """Update job config when providers depart. + + When a Grafana dashboard provider departs, the configuration + for that provider is removed from the list of dashboards + """ + if not self._charm.unit.is_leader(): + return + + self._remove_all_dashboards_for_relation(event.relation) + + def _render_dashboards_and_signal_changed(self, relation: Relation) -> bool: # type: ignore + """Validate a given dashboard. + + Verify that the passed dashboard data is able to be found in our list + of datasources and will render. If they do, let the charm know by + emitting an event. + + Args: + relation: Relation; The relation the dashboard is associated with. + + Returns: + a boolean indicating whether an event should be emitted + """ + other_app = relation.app + + raw_data = relation.data[other_app].get("dashboards", "") # pyright: ignore + + if not raw_data: + logger.warning( + "No dashboard data found in the %s:%s relation", + self._relation_name, + str(relation.id), + ) + return False + + data = json.loads(raw_data) + + # The only piece of data needed on this side of the relations is "templates" + templates = data.pop("templates") + + # The dashboards are WAY too big since this ultimately calls out to Juju to + # set the relation data, and it overflows the maximum argument length for + # subprocess, so we have to use b64, annoyingly. + # Worse, Python3 expects absolutely everything to be a byte, and a plain + # `base64.b64encode()` is still too large, so we have to go through hoops + # of encoding to byte, compressing with lzma, converting to base64 so it + # can be converted to JSON, then all the way back. + + rendered_dashboards = [] + relation_has_invalid_dashboards = False + + for _, (fname, template) in enumerate(templates.items()): + content = None + error = None + topology = template.get("juju_topology", {}) + try: + content = _decode_dashboard_content(template["content"]) + inject_dropdowns = template.get("inject_dropdowns", True) + content = self._manage_dashboard_uid(content, template) + content = _convert_dashboard_fields(content, inject_dropdowns) + + if topology: + content = _inject_labels(content, topology, self._tranformer) + + content = _encode_dashboard_content(content) + except lzma.LZMAError as e: + error = str(e) + relation_has_invalid_dashboards = True + except json.JSONDecodeError as e: + error = str(e.msg) + logger.warning("Invalid JSON in Grafana dashboard: {}".format(fname)) + continue + + # Prepend the relation name and ID to the dashboard ID to avoid clashes with + # multiple relations with apps from the same charm, or having dashboards with + # the same ids inside their charm operators + rendered_dashboards.append( + { + "id": "{}:{}/{}".format(relation.name, relation.id, fname), + "original_id": fname, + "content": content if content else None, + "template": template, + "valid": (error is None), + "error": error, + } + ) + + if relation_has_invalid_dashboards: + self._remove_all_dashboards_for_relation(relation) + + invalid_templates = [ + data["original_id"] for data in rendered_dashboards if not data["valid"] + ] + + logger.warning( + "Cannot add one or more Grafana dashboards from relation '{}:{}': the following " + "templates are invalid: {}".format( + relation.name, + relation.id, + invalid_templates, + ) + ) + + relation.data[self._charm.app]["event"] = json.dumps( + { + "errors": [ + { + "dashboard_id": rendered_dashboard["original_id"], + "error": rendered_dashboard["error"], + } + for rendered_dashboard in rendered_dashboards + if rendered_dashboard["error"] + ] + } + ) + + # Dropping dashboards for a relation needs to be signalled + return True + + stored_data = rendered_dashboards + currently_stored_data = self._get_stored_dashboards(relation.id) + + coerced_data = _type_convert_stored(currently_stored_data) if currently_stored_data else {} + + if not coerced_data == stored_data: + stored_dashboards = self.get_peer_data("dashboards") + stored_dashboards[relation.id] = stored_data + self.set_peer_data("dashboards", stored_dashboards) + return True + return None # type: ignore + + def _manage_dashboard_uid(self, dashboard: str, template: dict) -> str: + """Add an uid to the dashboard if it is not present.""" + dashboard_dict = json.loads(dashboard) + + if not dashboard_dict.get("uid", None) and "dashboard_alt_uid" in template: + dashboard_dict["uid"] = template["dashboard_alt_uid"] + + return json.dumps(dashboard_dict) + + def _remove_all_dashboards_for_relation(self, relation: Relation) -> None: + """If an errored dashboard is in stored data, remove it and trigger a deletion.""" + if self._get_stored_dashboards(relation.id): + stored_dashboards = self.get_peer_data("dashboards") + stored_dashboards.pop(str(relation.id)) + self.set_peer_data("dashboards", stored_dashboards) + self.on.dashboards_changed.emit() # pyright: ignore + + def _to_external_object(self, relation_id, dashboard): + return { + "id": dashboard["original_id"], + "relation_id": relation_id, + "charm": dashboard["template"]["charm"], + "content": _decode_dashboard_content(dashboard["content"]), + } + + @property + def dashboards(self) -> List[Dict]: + """Get a list of known dashboards across all instances of the monitored relation. + + Returns: a list of known dashboards. The JSON of each of the dashboards is available + in the `content` field of the corresponding `dict`. + """ + dashboards = [] + + for _, (relation_id, dashboards_for_relation) in enumerate( + self.get_peer_data("dashboards").items() + ): + for dashboard in dashboards_for_relation: + dashboards.append(self._to_external_object(relation_id, dashboard)) + + return dashboards + + def _get_stored_dashboards(self, relation_id: int) -> list: + """Pull stored dashboards out of the peer data bucket.""" + return self.get_peer_data("dashboards").get(str(relation_id), {}) + + def _set_default_data(self) -> None: + """Set defaults if they are not in peer relation data.""" + data = {"dashboards": {}} # type: ignore + for k, v in data.items(): + if not self.get_peer_data(k): + self.set_peer_data(k, v) + + def set_peer_data(self, key: str, data: Any) -> None: + """Put information into the peer data bucket instead of `StoredState`.""" + self._charm.peers.data[self._charm.app][key] = json.dumps(data) # type: ignore[attr-defined] + + def get_peer_data(self, key: str) -> Any: + """Retrieve information from the peer data bucket instead of `StoredState`.""" + data = self._charm.peers.data[self._charm.app].get(key, "") # type: ignore[attr-defined] + return json.loads(data) if data else {} + + +class GrafanaDashboardAggregator(Object): + """API to retrieve Grafana dashboards from machine dashboards. + + The :class:`GrafanaDashboardAggregator` object provides a way to + collate and aggregate Grafana dashboards from reactive/machine charms + and transport them into Charmed Operators, using Juju topology. + For detailed usage instructions, see the documentation for + :module:`cos-proxy-operator`, as this class is intended for use as a + single point of intersection rather than use in individual charms. + + Since :class:`GrafanaDashboardAggregator` serves as a bridge between + Canonical Observability Stack Charmed Operators and Reactive Charms, + deployed in a Reactive Juju model, both a target relation which is + used to collect events from Reactive charms and a `grafana_relation` + which is used to send the collected data back to the Canonical + Observability Stack are required. + + In its most streamlined usage, :class:`GrafanaDashboardAggregator` is + integrated in a charmed operator as follows: + self.grafana = GrafanaDashboardAggregator(self) + + Args: + charm: a :class:`CharmBase` object which manages this + :class:`GrafanaProvider` object. Generally this is + `self` in the instantiating class. + target_relation: a :string: name of a relation managed by this + :class:`GrafanaDashboardAggregator`, which is used to communicate + with reactive/machine charms it defaults to "dashboards". + grafana_relation: a :string: name of a relation used by this + :class:`GrafanaDashboardAggregator`, which is used to communicate + with charmed grafana. It defaults to "downstream-grafana-dashboard" + """ + + _stored = StoredState() + on = GrafanaProviderEvents() # pyright: ignore + + def __init__( + self, + charm: CharmBase, + target_relation: str = "dashboards", + grafana_relation: str = "downstream-grafana-dashboard", + ): + super().__init__(charm, grafana_relation) + + # Reactive charms may be RPC-ish and not leave reliable data around. Keep + # StoredState here + self._stored.set_default( # type: ignore + dashboard_templates={}, + id_mappings={}, + ) + + self._charm = charm + self._target_relation = target_relation + self._grafana_relation = grafana_relation + + self.framework.observe( + self._charm.on[self._grafana_relation].relation_joined, + self._update_remote_grafana, + ) + self.framework.observe( + self._charm.on[self._grafana_relation].relation_changed, + self._update_remote_grafana, + ) + self.framework.observe( + self._charm.on[self._target_relation].relation_changed, + self.update_dashboards, + ) + self.framework.observe( + self._charm.on[self._target_relation].relation_broken, + self.remove_dashboards, + ) + + def update_dashboards(self, event: RelationEvent) -> None: + """If we get a dashboard from a reactive charm, parse it out and update.""" + if self._charm.unit.is_leader(): + self._upset_dashboards_on_event(event) + + def _upset_dashboards_on_event(self, event: RelationEvent) -> None: + """Update the dashboards in the relation data bucket.""" + dashboards = self._handle_reactive_dashboards(event) + + if not dashboards: + logger.warning( + "Could not find dashboard data after a relation change for {}".format(event.app) + ) + return + + for id in dashboards: + self._stored.dashboard_templates[id] = self._content_to_dashboard_object( # type: ignore + dashboards[id], event + ) + + self._stored.id_mappings[event.app.name] = dashboards # type: ignore + self._update_remote_grafana(event) + + def _update_remote_grafana(self, _: Optional[RelationEvent] = None) -> None: + """Push dashboards to the downstream Grafana relation.""" + # It's still ridiculous to add a UUID here, but needed + stored_data = { + "templates": _type_convert_stored(self._stored.dashboard_templates), # pyright: ignore + "uuid": str(uuid.uuid4()), + } + + if self._charm.unit.is_leader(): + for grafana_relation in self.model.relations[self._grafana_relation]: + grafana_relation.data[self._charm.app]["dashboards"] = json.dumps(stored_data) + + def remove_dashboards(self, event: RelationBrokenEvent) -> None: + """Remove a dashboard if the relation is broken.""" + app_ids = _type_convert_stored(self._stored.id_mappings.get(event.app.name, "")) # type: ignore + + if not app_ids: + logger.info("Could not look up stored dashboards for %s", event.app.name) # type: ignore + return + + del self._stored.id_mappings[event.app.name] # type: ignore + for id in app_ids: + del self._stored.dashboard_templates[id] # type: ignore + + stored_data = { + "templates": _type_convert_stored(self._stored.dashboard_templates), # pyright: ignore + "uuid": str(uuid.uuid4()), + } + + if self._charm.unit.is_leader(): + for grafana_relation in self.model.relations[self._grafana_relation]: + grafana_relation.data[self._charm.app]["dashboards"] = json.dumps(stored_data) + + # Yes, this has a fair amount of branching. It's not that complex, though + def _strip_existing_datasources(self, dash: dict) -> dict: # noqa: C901 + """Remove existing reactive charm datasource templating out. + + This method iterates through *known* places where reactive charms may set + data in contributed dashboards and removes them. + + `dashboard["__inputs"]` is a property sometimes set when exporting dashboards from + the Grafana UI. It is not present in earlier Grafana versions, and can be disabled + in 5.3.4 and above (optionally). If set, any values present will be substituted on + import. Some reactive charms use this for Prometheus. COS uses dropdown selectors + for datasources, and leaving this present results in "default" datasource values + which are broken. + + Similarly, `dashboard["templating"]["list"][N]["name"] == "host"` can be used to + set a `host` variable for use in dashboards which is not meaningful in the context + of Juju topology and will yield broken dashboards. + + Further properties may be discovered. + """ + try: + if "list" in dash["templating"]: + for i in range(len(dash["templating"]["list"])): + if ( + "datasource" in dash["templating"]["list"][i] + and dash["templating"]["list"][i]["datasource"] is not None + ): + if "Juju" in dash["templating"]["list"][i].get("datasource", ""): + dash["templating"]["list"][i]["datasource"] = r"${prometheusds}" + + # Strip out newly-added 'juju_application' template variables which + # don't line up with our drop-downs + dash_mutable = dash + for i in range(len(dash["templating"]["list"])): + if ( + "name" in dash["templating"]["list"][i] + and dash["templating"]["list"][i].get("name", "") == "app" + ): + del dash_mutable["templating"]["list"][i] + + if dash_mutable: + dash = dash_mutable + except KeyError: + logger.debug("No existing templating data in dashboard") + + if "__inputs" in dash: + inputs = dash + for i in range(len(dash["__inputs"])): + if dash["__inputs"][i].get("pluginName", "") == "Prometheus": + del inputs["__inputs"][i] + if inputs: + dash["__inputs"] = inputs["__inputs"] + else: + del dash["__inputs"] + + return dash + + def _handle_reactive_dashboards(self, event: RelationEvent) -> Optional[Dict]: + """Look for a dashboard in relation data (during a reactive hook) or builtin by name.""" + if not self._charm.unit.is_leader(): + return {} + + templates = [] + id = "" + + # Reactive data can reliably be pulled out of events. In theory, if we got an event, + # it's on the bucket, but using event explicitly keeps the mental model in + # place for reactive + for k in event.relation.data[event.unit].keys(): # type: ignore + if k.startswith("request_"): + templates.append(json.loads(event.relation.data[event.unit][k])["dashboard"]) # type: ignore + + for k in event.relation.data[event.app].keys(): # type: ignore + if k.startswith("request_"): + templates.append(json.loads(event.relation.data[event.app][k])["dashboard"]) # type: ignore + + builtins = self._maybe_get_builtin_dashboards(event) + + if not templates and not builtins: + logger.warning("NOTHING!") + return {} + + dashboards = {} + for t in templates: + # This seems ridiculous, too, but to get it from a "dashboards" key in serialized JSON + # in the bucket back out to the actual "dashboard" we _need_, this is the way + # This is not a mistake -- there's a double nesting in reactive charms, and + # Grafana won't load it. We have to unbox: + # event.relation.data[event.]["request_*"]["dashboard"]["dashboard"], + # and the final unboxing is below. + # + # Apparently SOME newer dashboards (such as Ceph) do not have this double nesting, so + # now we get to account for both :toot: + dash = t.get("dashboard", {}) or t + + # Replace values with LMA-style templating + dash = self._strip_existing_datasources(dash) + dash = json.dumps(dash) + + # Replace the old-style datasource templates + dash = re.sub(r"<< datasource >>", r"${prometheusds}", dash) + dash = re.sub(r'"datasource": "prom.*?"', r'"datasource": "${prometheusds}"', dash) + dash = re.sub( + r'"datasource": "\$datasource"', r'"datasource": "${prometheusds}"', dash + ) + dash = re.sub(r'"uid": "\$datasource"', r'"uid": "${prometheusds}"', dash) + dash = re.sub( + r'"datasource": "(!?\w)[\w|\s|-]+?Juju generated.*?"', + r'"datasource": "${prometheusds}"', + dash, + ) + + # Yank out "new"+old LMA topology + dash = re.sub( + r'(,?\s?juju_application=~)\\"\$app\\"', r'\1\\"$juju_application\\"', dash + ) + + # Replace old piechart panels + dash = re.sub(r'"type": "grafana-piechart-panel"', '"type": "piechart"', dash) + + from jinja2 import DebugUndefined, Template + + content = _encode_dashboard_content( + Template(dash, undefined=DebugUndefined).render(datasource=r"${prometheusds}") # type: ignore + ) + id = "prog:{}".format(content[-24:-16]) + + dashboards[id] = content + return {**builtins, **dashboards} + + def _maybe_get_builtin_dashboards(self, event: RelationEvent) -> Dict: + """Tries to match the event with an included dashboard. + + Scans dashboards packed with the charm instantiating this class, and tries to match + one with the event. There is no guarantee that any given event will match a builtin, + since each charm instantiating this class may include a different set of dashboards, + or none. + """ + builtins = {} + dashboards_path = None + + try: + dashboards_path = _resolve_dir_against_charm_path( + self._charm, "src/grafana_dashboards" + ) + except InvalidDirectoryPathError as e: + logger.warning( + "Invalid Grafana dashboards folder at %s: %s", + e.grafana_dashboards_absolute_path, + e.message, + ) + + if dashboards_path: + + def is_dashboard(p: Path) -> bool: + return p.is_file() and p.name.endswith((".json", ".json.tmpl", ".tmpl")) + + for path in filter(is_dashboard, Path(dashboards_path).glob("*")): + # path = Path(path) + if event.app.name in path.name: # type: ignore + id = "file:{}".format(path.stem) + builtins[id] = self._content_to_dashboard_object( + _encode_dashboard_content(path.read_bytes()), event + ) + + return builtins + + def _content_to_dashboard_object(self, content: str, event: RelationEvent) -> Dict: + return { + "charm": event.app.name, # type: ignore + "content": content, + "juju_topology": self._juju_topology(event), + "inject_dropdowns": True, + } + + # This is not actually used in the dashboards, but is present to provide a secondary + # salt to ensure uniqueness in the dict keys in case individual charm units provide + # dashboards + def _juju_topology(self, event: RelationEvent) -> Dict: + return { + "model": self._charm.model.name, + "model_uuid": self._charm.model.uuid, + "application": event.app.name, # type: ignore + "unit": event.unit.name, # type: ignore + } + + +class CosTool: + """Uses cos-tool to inject label matchers into alert rule expressions and validate rules.""" + + _path = None + _disabled = False + + def __init__(self, charm): + self._charm = charm + + @property + def path(self): + """Lazy lookup of the path of cos-tool.""" + if self._disabled: + return None + if not self._path: + self._path = self._get_tool_path() + if not self._path: + logger.debug("Skipping injection of juju topology as label matchers") + self._disabled = True + return self._path + + def apply_label_matchers(self, rules: dict, type: str) -> dict: + """Will apply label matchers to the expression of all alerts in all supplied groups.""" + if not self.path: + return rules + for group in rules["groups"]: + rules_in_group = group.get("rules", []) + for rule in rules_in_group: + topology = {} + # if the user for some reason has provided juju_unit, we'll need to honor it + # in most cases, however, this will be empty + for label in [ + "juju_model", + "juju_model_uuid", + "juju_application", + "juju_charm", + "juju_unit", + ]: + if label in rule["labels"]: + topology[label] = rule["labels"][label] + + rule["expr"] = self.inject_label_matchers(rule["expr"], topology, type) + return rules + + def validate_alert_rules(self, rules: dict) -> Tuple[bool, str]: + """Will validate correctness of alert rules, returning a boolean and any errors.""" + if not self.path: + logger.debug("`cos-tool` unavailable. Not validating alert correctness.") + return True, "" + + with tempfile.TemporaryDirectory() as tmpdir: + rule_path = Path(tmpdir + "/validate_rule.yaml") + + # Smash "our" rules format into what upstream actually uses, which is more like: + # + # groups: + # - name: foo + # rules: + # - alert: SomeAlert + # expr: up + # - alert: OtherAlert + # expr: up + transformed_rules = {"groups": []} # type: ignore + for rule in rules["groups"]: + transformed = {"name": str(uuid.uuid4()), "rules": [rule]} + transformed_rules["groups"].append(transformed) + + rule_path.write_text(yaml.dump(transformed_rules)) + + args = [str(self.path), "validate", str(rule_path)] + # noinspection PyBroadException + try: + self._exec(args) + return True, "" + except subprocess.CalledProcessError as e: + logger.debug("Validating the rules failed: %s", e.output) + return False, ", ".join([line for line in e.output if "error validating" in line]) + + def inject_label_matchers(self, expression: str, topology: dict, type: str) -> str: + """Add label matchers to an expression.""" + if not topology: + return expression + if not self.path: + logger.debug("`cos-tool` unavailable. Leaving expression unchanged: %s", expression) + return expression + args = [str(self.path), "--format", type, "transform"] + + variable_topology = {k: "${}".format(k) for k in topology.keys()} + args.extend( + [ + "--label-matcher={}={}".format(key, value) + for key, value in variable_topology.items() + ] + ) + + # Pass a leading "--" so expressions with a negation or subtraction aren't interpreted as + # flags + args.extend(["--", "{}".format(expression)]) + # noinspection PyBroadException + try: + return re.sub(r'="\$juju', r'=~"$juju', self._exec(args)) + except subprocess.CalledProcessError as e: + logger.debug('Applying the expression failed: "%s", falling back to the original', e) + return expression + + def _get_tool_path(self) -> Optional[Path]: + arch = platform.machine() + arch = "amd64" if arch == "x86_64" else arch + res = "cos-tool-{}".format(arch) + try: + path = Path(res).resolve() + path.chmod(0o777) + return path + except NotImplementedError: + logger.debug("System lacks support for chmod") + except FileNotFoundError: + logger.debug('Could not locate cos-tool at: "{}"'.format(res)) + return None + + def _exec(self, cmd) -> str: + result = subprocess.run(cmd, check=True, stdout=subprocess.PIPE) + output = result.stdout.decode("utf-8").strip() + return output diff --git a/charms/jimm-k8s/lib/charms/loki_k8s/v0/loki_push_api.py b/charms/jimm-k8s/lib/charms/loki_k8s/v0/loki_push_api.py new file mode 100644 index 000000000..6bdf07844 --- /dev/null +++ b/charms/jimm-k8s/lib/charms/loki_k8s/v0/loki_push_api.py @@ -0,0 +1,2461 @@ +#!/usr/bin/env python3 +# Copyright 2021 Canonical Ltd. +# See LICENSE file for licensing details. +# +# Learn more at: https://juju.is/docs/sdk + +r"""## Overview. + +This document explains how to use the two principal objects this library provides: + +- `LokiPushApiProvider`: This object is meant to be used by any Charmed Operator that needs to +implement the provider side of the `loki_push_api` relation interface. For instance, a Loki charm. +The provider side of the relation represents the server side, to which logs are being pushed. + +- `LokiPushApiConsumer`: This object is meant to be used by any Charmed Operator that needs to +send log to Loki by implementing the consumer side of the `loki_push_api` relation interface. +For instance, a Promtail or Grafana agent charm which needs to send logs to Loki. + +- `LogProxyConsumer`: This object can be used by any Charmed Operator which needs to +send telemetry, such as logs, to Loki through a Log Proxy by implementing the consumer side of the +`loki_push_api` relation interface. + +Filtering logs in Loki is largely performed on the basis of labels. In the Juju ecosystem, Juju +topology labels are used to uniquely identify the workload which generates telemetry like logs. + +In order to be able to control the labels on the logs pushed this object adds a Pebble layer +that runs Promtail in the workload container, injecting Juju topology labels into the +logs on the fly. + +## LokiPushApiProvider Library Usage + +This object may be used by any Charmed Operator which implements the `loki_push_api` interface. +For instance, Loki or Grafana Agent. + +For this purpose a charm needs to instantiate the `LokiPushApiProvider` object with one mandatory +and three optional arguments. + +- `charm`: A reference to the parent (Loki) charm. + +- `relation_name`: The name of the relation that the charm uses to interact + with its clients, which implement `LokiPushApiConsumer` or `LogProxyConsumer`. + + If provided, this relation name must match a provided relation in metadata.yaml with the + `loki_push_api` interface. + + The default relation name is "logging" for `LokiPushApiConsumer` and "log-proxy" for + `LogProxyConsumer`. + + For example, a provider's `metadata.yaml` file may look as follows: + + ```yaml + provides: + logging: + interface: loki_push_api + ``` + + Subsequently, a Loki charm may instantiate the `LokiPushApiProvider` in its constructor as + follows: + + from charms.loki_k8s.v0.loki_push_api import LokiPushApiProvider + from loki_server import LokiServer + ... + + class LokiOperatorCharm(CharmBase): + ... + + def __init__(self, *args): + super().__init__(*args) + ... + self._loki_ready() + ... + + def _loki_ready(self): + try: + version = self._loki_server.version + self.loki_provider = LokiPushApiProvider(self) + logger.debug("Loki Provider is available. Loki version: %s", version) + except LokiServerNotReadyError as e: + self.unit.status = MaintenanceStatus(str(e)) + except LokiServerError as e: + self.unit.status = BlockedStatus(str(e)) + + - `port`: Loki Push Api endpoint port. Default value: 3100. + - `rules_dir`: Directory to store alert rules. Default value: "/loki/rules". + + +The `LokiPushApiProvider` object has several responsibilities: + +1. Set the URL of the Loki Push API in the relation application data bag; the URL + must be unique to all instances (e.g. using a load balancer). + +2. Set the Promtail binary URL (`promtail_binary_zip_url`) so clients that use + `LogProxyConsumer` object could download and configure it. + +3. Process the metadata of the consumer application, provided via the + "metadata" field of the consumer data bag, which are used to annotate the + alert rules (see next point). An example for "metadata" is the following: + + {'model': 'loki', + 'model_uuid': '0b7d1071-ded2-4bf5-80a3-10a81aeb1386', + 'application': 'promtail-k8s' + } + +4. Process alert rules set into the relation by the `LokiPushApiConsumer` + objects, e.g.: + + '{ + "groups": [{ + "name": "loki_0b7d1071-ded2-4bf5-80a3-10a81aeb1386_promtail-k8s_alerts", + "rules": [{ + "alert": "HighPercentageError", + "expr": "sum(rate({app=\\"foo\\", env=\\"production\\"} |= \\"error\\" [5m])) + by (job) \\n /\\nsum(rate({app=\\"foo\\", env=\\"production\\"}[5m])) + by (job)\\n > 0.05 + \\n", "for": "10m", + "labels": { + "severity": "page", + "juju_model": "loki", + "juju_model_uuid": "0b7d1071-ded2-4bf5-80a3-10a81aeb1386", + "juju_application": "promtail-k8s" + }, + "annotations": { + "summary": "High request latency" + } + }] + }] + }' + + +Once these alert rules are sent over relation data, the `LokiPushApiProvider` object +stores these files in the directory `/loki/rules` inside the Loki charm container. After +storing alert rules files, the object will check alert rules by querying Loki API +endpoint: [`loki/api/v1/rules`](https://grafana.com/docs/loki/latest/api/#list-rule-groups). +If there are changes in the alert rules a `loki_push_api_alert_rules_changed` event will +be emitted with details about the `RelationEvent` which triggered it. + +This events should be observed in the charm that uses `LokiPushApiProvider`: + +```python + def __init__(self, *args): + super().__init__(*args) + ... + self.loki_provider = LokiPushApiProvider(self) + self.framework.observe( + self.loki_provider.on.loki_push_api_alert_rules_changed, + self._loki_push_api_alert_rules_changed, + ) +``` + + +## LokiPushApiConsumer Library Usage + +This Loki charm interacts with its clients using the Loki charm library. Charms +seeking to send log to Loki, must do so using the `LokiPushApiConsumer` object from +this charm library. + +> **NOTE**: `LokiPushApiConsumer` also depends on an additional charm library. +> +> Ensure sure you `charmcraft fetch-lib charms.observability_libs.v0.juju_topology` +> when using this library. + +For the simplest use cases, using the `LokiPushApiConsumer` object only requires +instantiating it, typically in the constructor of your charm (the one which +sends logs). + +```python +from charms.loki_k8s.v0.loki_push_api import LokiPushApiConsumer + +class LokiClientCharm(CharmBase): + + def __init__(self, *args): + super().__init__(*args) + ... + self._loki_consumer = LokiPushApiConsumer(self) +``` + +The `LokiPushApiConsumer` constructor requires two things: + +- A reference to the parent (LokiClientCharm) charm. + +- Optionally, the name of the relation that the Loki charm uses to interact + with its clients. If provided, this relation name must match a required + relation in metadata.yaml with the `loki_push_api` interface. + + This argument is not required if your metadata.yaml has precisely one + required relation in metadata.yaml with the `loki_push_api` interface, as the + lib will automatically resolve the relation name inspecting the using the + meta information of the charm + +Any time the relation between a Loki provider charm and a Loki consumer charm is +established, a `LokiPushApiEndpointJoined` event is fired. In the consumer side +is it possible to observe this event with: + +```python + +self.framework.observe( + self._loki_consumer.on.loki_push_api_endpoint_joined, + self._on_loki_push_api_endpoint_joined, +) +``` + +Any time there are departures in relations between the consumer charm and Loki +the consumer charm is informed, through a `LokiPushApiEndpointDeparted` event, for instance: + +```python +self.framework.observe( + self._loki_consumer.on.loki_push_api_endpoint_departed, + self._on_loki_push_api_endpoint_departed, +) +``` + +The consumer charm can then choose to update its configuration in both situations. + +Note that LokiPushApiConsumer does not add any labels automatically on its own. In +order to better integrate with the Canonical Observability Stack, you may want to configure your +software to add Juju topology labels. The +[observability-libs](https://charmhub.io/observability-libs) library can be used to get topology +labels in charm code. See :func:`LogProxyConsumer._scrape_configs` for an example of how +to do this with promtail. + +## LogProxyConsumer Library Usage + +Let's say that we have a workload charm that produces logs, and we need to send those logs to a +workload implementing the `loki_push_api` interface, such as `Loki` or `Grafana Agent`. + +Adopting this object in a Charmed Operator consist of two steps: + +1. Use the `LogProxyConsumer` class by instantiating it in the `__init__` method of the charmed + operator. There are two ways to get logs in to promtail. You can give it a list of files to + read, or you can write to it using the syslog protocol. + + For example: + + ```python + from charms.loki_k8s.v0.loki_push_api import LogProxyConsumer + + ... + + def __init__(self, *args): + ... + self._log_proxy = LogProxyConsumer( + charm=self, log_files=LOG_FILES, container_name=PEER, enable_syslog=True + ) + + self.framework.observe( + self._log_proxy.on.promtail_digest_error, + self._promtail_error, + ) + + def _promtail_error(self, event): + logger.error(event.message) + self.unit.status = BlockedStatus(event.message) + ``` + + Any time the relation between a provider charm and a LogProxy consumer charm is + established, a `LogProxyEndpointJoined` event is fired. In the consumer side is it + possible to observe this event with: + + ```python + + self.framework.observe( + self._log_proxy.on.log_proxy_endpoint_joined, + self._on_log_proxy_endpoint_joined, + ) + ``` + + Any time there are departures in relations between the consumer charm and the provider + the consumer charm is informed, through a `LogProxyEndpointDeparted` event, for instance: + + ```python + self.framework.observe( + self._log_proxy.on.log_proxy_endpoint_departed, + self._on_log_proxy_endpoint_departed, + ) + ``` + + The consumer charm can then choose to update its configuration in both situations. + + Note that: + + - `LOG_FILES` is a `list` containing the log files we want to send to `Loki` or + `Grafana Agent`, for instance: + + ```python + LOG_FILES = [ + "/var/log/apache2/access.log", + "/var/log/alternatives.log", + ] + ``` + + - `container_name` is the name of the container in which the application is running. + If in the Pod there is only one container, this argument can be omitted. + + - You can configure your syslog software using `localhost` as the address and the method + `LogProxyConsumer.syslog_port` to get the port, or, alternatively, if you are using rsyslog + you may use the method `LogProxyConsumer.rsyslog_config()`. + +2. Modify the `metadata.yaml` file to add: + + - The `log-proxy` relation in the `requires` section: + ```yaml + requires: + log-proxy: + interface: loki_push_api + optional: true + ``` + +Once the library is implemented in a Charmed Operator and a relation is established with +the charm that implements the `loki_push_api` interface, the library will inject a +Pebble layer that runs Promtail in the workload container to send logs. + +By default, the promtail binary injected into the container will be downloaded from the internet. +If, for any reason, the container has limited network access, you may allow charm administrators +to provide their own promtail binary at runtime by adding the following snippet to your charm +metadata: + +```yaml +resources: + promtail-bin: + type: file + description: Promtail binary for logging + filename: promtail-linux +``` + +Which would then allow operators to deploy the charm this way: + +``` +juju deploy \ + ./your_charm.charm \ + --resource promtail-bin=/tmp/promtail-linux-amd64 +``` + +If a different resource name is used, it can be specified with the `promtail_resource_name` +argument to the `LogProxyConsumer` constructor. + +The object can emit a `PromtailDigestError` event: + +- Promtail binary cannot be downloaded. +- The sha256 sum mismatch for promtail binary. + +The object can raise a `ContainerNotFoundError` event: + +- No `container_name` parameter has been specified and the Pod has more than 1 container. + +These can be monitored via the PromtailDigestError events via: + +```python + self.framework.observe( + self._loki_consumer.on.promtail_digest_error, + self._promtail_error, + ) + + def _promtail_error(self, event): + logger.error(msg) + self.unit.status = BlockedStatus(event.message) + ) +``` + +## Alerting Rules + +This charm library also supports gathering alerting rules from all related Loki client +charms and enabling corresponding alerts within the Loki charm. Alert rules are +automatically gathered by `LokiPushApiConsumer` object from a directory conventionally +named `loki_alert_rules`. + +This directory must reside at the top level in the `src` folder of the +consumer charm. Each file in this directory is assumed to be a single alert rule +in YAML format. The file name must have the `.rule` extension. +The format of this alert rule conforms to the +[Loki docs](https://grafana.com/docs/loki/latest/rules/#alerting-rules). + +An example of the contents of one such file is shown below. + +```yaml +alert: HighPercentageError +expr: | + sum(rate({%%juju_topology%%} |= "error" [5m])) by (job) + / + sum(rate({%%juju_topology%%}[5m])) by (job) + > 0.05 +for: 10m +labels: + severity: page +annotations: + summary: High request latency + +``` + +It is **critical** to use the `%%juju_topology%%` filter in the expression for the alert +rule shown above. This filter is a stub that is automatically replaced by the +`LokiPushApiConsumer` following Loki Client's Juju topology (application, model and its +UUID). Such a topology filter is essential to ensure that alert rules submitted by one +provider charm generates alerts only for that same charm. + +The Loki charm may be related to multiple Loki client charms. Without this, filter +rules submitted by one provider charm will also result in corresponding alerts for other +provider charms. Hence, every alert rule expression must include such a topology filter stub. + +Gathering alert rules and generating rule files within the Loki charm is easily done using +the `alerts()` method of `LokiPushApiProvider`. Alerts generated by Loki will automatically +include Juju topology labels in the alerts. These labels indicate the source of the alert. + +The following labels are automatically added to every alert + +- `juju_model` +- `juju_model_uuid` +- `juju_application` + + +Whether alert rules files does not contain the keys `alert` or `expr` or there is no alert +rules file in `alert_rules_path` a `loki_push_api_alert_rules_error` event is emitted. + +To handle these situations the event must be observed in the `LokiClientCharm` charm.py file: + +```python +class LokiClientCharm(CharmBase): + + def __init__(self, *args): + super().__init__(*args) + ... + self._loki_consumer = LokiPushApiConsumer(self) + + self.framework.observe( + self._loki_consumer.on.loki_push_api_alert_rules_error, + self._alert_rules_error + ) + + def _alert_rules_error(self, event): + self.unit.status = BlockedStatus(event.message) +``` + +## Relation Data + +The Loki charm uses both application and unit relation data to obtain information regarding +Loki Push API and alert rules. + +Units of consumer charm send their alert rules over app relation data using the `alert_rules` +key. +""" + +import json +import logging +import os +import platform +import re +import socket +import subprocess +import tempfile +import typing +from copy import deepcopy +from gzip import GzipFile +from hashlib import sha256 +from io import BytesIO +from pathlib import Path +from typing import Any, Dict, List, Optional, Tuple, Union, cast +from urllib import request +from urllib.error import HTTPError + +import yaml +from charms.observability_libs.v0.juju_topology import JujuTopology +from ops.charm import ( + CharmBase, + HookEvent, + RelationBrokenEvent, + RelationCreatedEvent, + RelationDepartedEvent, + RelationEvent, + RelationJoinedEvent, + RelationRole, + WorkloadEvent, +) +from ops.framework import EventBase, EventSource, Object, ObjectEvents +from ops.model import Container, ModelError, Relation +from ops.pebble import APIError, ChangeError, PathError, ProtocolError + +# The unique Charmhub library identifier, never change it +LIBID = "bf76f23cdd03464b877c52bd1d2f563e" + +# Increment this major API version when introducing breaking changes +LIBAPI = 0 + +# Increment this PATCH version before using `charmcraft publish-lib` or reset +# to 0 if you are raising the major API version +LIBPATCH = 19 + +logger = logging.getLogger(__name__) + +RELATION_INTERFACE_NAME = "loki_push_api" +DEFAULT_RELATION_NAME = "logging" +DEFAULT_ALERT_RULES_RELATIVE_PATH = "./src/loki_alert_rules" +DEFAULT_LOG_PROXY_RELATION_NAME = "log-proxy" + +PROMTAIL_BASE_URL = "https://github.com/canonical/loki-k8s-operator/releases/download" +# To update Promtail version you only need to change the PROMTAIL_VERSION and +# update all sha256 sums in PROMTAIL_BINARIES. To support a new architecture +# you only need to add a new key value pair for the architecture in PROMTAIL_BINARIES. +PROMTAIL_VERSION = "v2.5.0" +PROMTAIL_BINARIES = { + "amd64": { + "filename": "promtail-static-amd64", + "zipsha": "543e333b0184e14015a42c3c9e9e66d2464aaa66eca48b29e185a6a18f67ab6d", + "binsha": "17e2e271e65f793a9fbe81eab887b941e9d680abe82d5a0602888c50f5e0cac9", + }, +} + +# Paths in `charm` container +BINARY_DIR = "/tmp" + +# Paths in `workload` container +WORKLOAD_BINARY_DIR = "/opt/promtail" +WORKLOAD_CONFIG_DIR = "/etc/promtail" +WORKLOAD_CONFIG_FILE_NAME = "promtail_config.yaml" +WORKLOAD_CONFIG_PATH = "{}/{}".format(WORKLOAD_CONFIG_DIR, WORKLOAD_CONFIG_FILE_NAME) +WORKLOAD_POSITIONS_PATH = "{}/positions.yaml".format(WORKLOAD_BINARY_DIR) +WORKLOAD_SERVICE_NAME = "promtail" + +HTTP_LISTEN_PORT = 9080 +GRPC_LISTEN_PORT = 9095 + + +class RelationNotFoundError(ValueError): + """Raised if there is no relation with the given name.""" + + def __init__(self, relation_name: str): + self.relation_name = relation_name + self.message = "No relation named '{}' found".format(relation_name) + + super().__init__(self.message) + + +class RelationInterfaceMismatchError(Exception): + """Raised if the relation with the given name has a different interface.""" + + def __init__( + self, + relation_name: str, + expected_relation_interface: str, + actual_relation_interface: str, + ): + self.relation_name = relation_name + self.expected_relation_interface = expected_relation_interface + self.actual_relation_interface = actual_relation_interface + self.message = ( + "The '{}' relation has '{}' as interface rather than the expected '{}'".format( + relation_name, actual_relation_interface, expected_relation_interface + ) + ) + super().__init__(self.message) + + +class RelationRoleMismatchError(Exception): + """Raised if the relation with the given name has a different direction.""" + + def __init__( + self, + relation_name: str, + expected_relation_role: RelationRole, + actual_relation_role: RelationRole, + ): + self.relation_name = relation_name + self.expected_relation_interface = expected_relation_role + self.actual_relation_role = actual_relation_role + self.message = "The '{}' relation has role '{}' rather than the expected '{}'".format( + relation_name, repr(actual_relation_role), repr(expected_relation_role) + ) + super().__init__(self.message) + + +def _validate_relation_by_interface_and_direction( + charm: CharmBase, + relation_name: str, + expected_relation_interface: str, + expected_relation_role: RelationRole, +): + """Verifies that a relation has the necessary characteristics. + + Verifies that the `relation_name` provided: (1) exists in metadata.yaml, + (2) declares as interface the interface name passed as `relation_interface` + and (3) has the right "direction", i.e., it is a relation that `charm` + provides or requires. + + Args: + charm: a `CharmBase` object to scan for the matching relation. + relation_name: the name of the relation to be verified. + expected_relation_interface: the interface name to be matched by the + relation named `relation_name`. + expected_relation_role: whether the `relation_name` must be either + provided or required by `charm`. + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the same relation interface + as specified via the `expected_relation_interface` argument. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the same role as specified + via the `expected_relation_role` argument. + """ + if relation_name not in charm.meta.relations: + raise RelationNotFoundError(relation_name) + + relation = charm.meta.relations[relation_name] + + actual_relation_interface = relation.interface_name + if actual_relation_interface != expected_relation_interface: + raise RelationInterfaceMismatchError( + relation_name, expected_relation_interface, actual_relation_interface + ) + + if expected_relation_role == RelationRole.provides: + if relation_name not in charm.meta.provides: + raise RelationRoleMismatchError( + relation_name, RelationRole.provides, RelationRole.requires + ) + elif expected_relation_role == RelationRole.requires: + if relation_name not in charm.meta.requires: + raise RelationRoleMismatchError( + relation_name, RelationRole.requires, RelationRole.provides + ) + else: + raise Exception("Unexpected RelationDirection: {}".format(expected_relation_role)) + + +class InvalidAlertRulePathError(Exception): + """Raised if the alert rules folder cannot be found or is otherwise invalid.""" + + def __init__( + self, + alert_rules_absolute_path: Path, + message: str, + ): + self.alert_rules_absolute_path = alert_rules_absolute_path + self.message = message + + super().__init__(self.message) + + +def _is_official_alert_rule_format(rules_dict: dict) -> bool: + """Are alert rules in the upstream format as supported by Loki. + + Alert rules in dictionary format are in "official" form if they + contain a "groups" key, since this implies they contain a list of + alert rule groups. + + Args: + rules_dict: a set of alert rules in Python dictionary format + + Returns: + True if alert rules are in official Loki file format. + """ + return "groups" in rules_dict + + +def _is_single_alert_rule_format(rules_dict: dict) -> bool: + """Are alert rules in single rule format. + + The Loki charm library supports reading of alert rules in a + custom format that consists of a single alert rule per file. This + does not conform to the official Loki alert rule file format + which requires that each alert rules file consists of a list of + alert rule groups and each group consists of a list of alert + rules. + + Alert rules in dictionary form are considered to be in single rule + format if in the least it contains two keys corresponding to the + alert rule name and alert expression. + + Returns: + True if alert rule is in single rule file format. + """ + # one alert rule per file + return set(rules_dict) >= {"alert", "expr"} + + +class AlertRules: + """Utility class for amalgamating Loki alert rule files and injecting juju topology. + + An `AlertRules` object supports aggregating alert rules from files and directories in both + official and single rule file formats using the `add_path()` method. All the alert rules + read are annotated with Juju topology labels and amalgamated into a single data structure + in the form of a Python dictionary using the `as_dict()` method. Such a dictionary can be + easily dumped into JSON format and exchanged over relation data. The dictionary can also + be dumped into YAML format and written directly into an alert rules file that is read by + Loki. Note that multiple `AlertRules` objects must not be written into the same file, + since Loki allows only a single list of alert rule groups per alert rules file. + + The official Loki format is a YAML file conforming to the Loki documentation + (https://grafana.com/docs/loki/latest/api/#list-rule-groups). + The custom single rule format is a subsection of the official YAML, having a single alert + rule, effectively "one alert per file". + """ + + # This class uses the following terminology for the various parts of a rule file: + # - alert rules file: the entire groups[] yaml, including the "groups:" key. + # - alert groups (plural): the list of groups[] (a list, i.e. no "groups:" key) - it is a list + # of dictionaries that have the "name" and "rules" keys. + # - alert group (singular): a single dictionary that has the "name" and "rules" keys. + # - alert rules (plural): all the alerts in a given alert group - a list of dictionaries with + # the "alert" and "expr" keys. + # - alert rule (singular): a single dictionary that has the "alert" and "expr" keys. + + def __init__(self, topology: Optional[JujuTopology] = None): + """Build and alert rule object. + + Args: + topology: a `JujuTopology` instance that is used to annotate all alert rules. + """ + self.topology = topology + self.tool = CosTool(None) + self.alert_groups = [] # type: List[dict] + + def _from_file(self, root_path: Path, file_path: Path) -> List[dict]: + """Read a rules file from path, injecting juju topology. + + Args: + root_path: full path to the root rules folder (used only for generating group name) + file_path: full path to a *.rule file. + + Returns: + A list of dictionaries representing the rules file, if file is valid (the structure is + formed by `yaml.safe_load` of the file); an empty list otherwise. + """ + with file_path.open() as rf: + # Load a list of rules from file then add labels and filters + try: + rule_file = yaml.safe_load(rf) or {} + + except Exception as e: + logger.error("Failed to read alert rules from %s: %s", file_path.name, e) + return [] + + if _is_official_alert_rule_format(rule_file): + alert_groups = rule_file["groups"] + elif _is_single_alert_rule_format(rule_file): + # convert to list of alert groups + # group name is made up from the file name + alert_groups = [{"name": file_path.stem, "rules": [rule_file]}] + else: + # invalid/unsupported + reason = "file is empty" if not rule_file else "unexpected file structure" + logger.error("Invalid rules file (%s): %s", reason, file_path.name) + return [] + + # update rules with additional metadata + for alert_group in alert_groups: + # update group name with topology and sub-path + alert_group["name"] = self._group_name( + str(root_path), + str(file_path), + alert_group["name"], + ) + + # add "juju_" topology labels + for alert_rule in alert_group["rules"]: + if "labels" not in alert_rule: + alert_rule["labels"] = {} + + if self.topology: + alert_rule["labels"].update(self.topology.label_matcher_dict) + # insert juju topology filters into a prometheus alert rule + # logql doesn't like empty matchers, so add a job matcher which hits + # any string as a "wildcard" which the topology labels will + # filter down + alert_rule["expr"] = self.tool.inject_label_matchers( + re.sub(r"%%juju_topology%%", r'job=~".+"', alert_rule["expr"]), + self.topology.label_matcher_dict, + ) + + return alert_groups + + def _group_name( + self, + root_path: typing.Union[Path, str], + file_path: typing.Union[Path, str], + group_name: str, + ) -> str: + """Generate group name from path and topology. + + The group name is made up of the relative path between the root dir_path, the file path, + and topology identifier. + + Args: + root_path: path to the root rules dir. + file_path: path to rule file. + group_name: original group name to keep as part of the new augmented group name + + Returns: + New group name, augmented by juju topology and relative path. + """ + file_path = Path(file_path) if not isinstance(file_path, Path) else file_path + root_path = Path(root_path) if not isinstance(root_path, Path) else root_path + rel_path = file_path.parent.relative_to(root_path.as_posix()) + + # We should account for both absolute paths and Windows paths. Convert it to a POSIX + # string, strip off any leading /, then join it + + path_str = "" + if not rel_path == Path("."): + # Get rid of leading / and optionally drive letters so they don't muck up + # the template later, since Path.parts returns them. The 'if relpath.is_absolute ...' + # isn't even needed since re.sub doesn't throw exceptions if it doesn't match, so it's + # optional, but it makes it clear what we're doing. + + # Note that Path doesn't actually care whether the path is valid just to instantiate + # the object, so we can happily strip that stuff out to make templating nicer + rel_path = Path( + re.sub(r"^([A-Za-z]+:)?/", "", rel_path.as_posix()) + if rel_path.is_absolute() + else str(rel_path) + ) + + # Get rid of relative path characters in the middle which both os.path and pathlib + # leave hanging around. We could use path.resolve(), but that would lead to very + # long template strings when rules come from pods and/or other deeply nested charm + # paths + path_str = "_".join(filter(lambda x: x not in ["..", "/"], rel_path.parts)) + + # Generate group name: + # - name, from juju topology + # - suffix, from the relative path of the rule file; + group_name_parts = [self.topology.identifier] if self.topology else [] + group_name_parts.extend([path_str, group_name, "alerts"]) + # filter to remove empty strings + return "_".join(filter(lambda x: x, group_name_parts)) + + @classmethod + def _multi_suffix_glob( + cls, dir_path: Path, suffixes: List[str], recursive: bool = True + ) -> list: + """Helper function for getting all files in a directory that have a matching suffix. + + Args: + dir_path: path to the directory to glob from. + suffixes: list of suffixes to include in the glob (items should begin with a period). + recursive: a flag indicating whether a glob is recursive (nested) or not. + + Returns: + List of files in `dir_path` that have one of the suffixes specified in `suffixes`. + """ + all_files_in_dir = dir_path.glob("**/*" if recursive else "*") + return list(filter(lambda f: f.is_file() and f.suffix in suffixes, all_files_in_dir)) + + def _from_dir(self, dir_path: Path, recursive: bool) -> List[dict]: + """Read all rule files in a directory. + + All rules from files for the same directory are loaded into a single + group. The generated name of this group includes juju topology. + By default, only the top directory is scanned; for nested scanning, pass `recursive=True`. + + Args: + dir_path: directory containing *.rule files (alert rules without groups). + recursive: flag indicating whether to scan for rule files recursively. + + Returns: + a list of dictionaries representing prometheus alert rule groups, each dictionary + representing an alert group (structure determined by `yaml.safe_load`). + """ + alert_groups = [] # type: List[dict] + + # Gather all alerts into a list of groups + for file_path in self._multi_suffix_glob(dir_path, [".rule", ".rules"], recursive): + alert_groups_from_file = self._from_file(dir_path, file_path) + if alert_groups_from_file: + logger.debug("Reading alert rule from %s", file_path) + alert_groups.extend(alert_groups_from_file) + + return alert_groups + + def add_path(self, path: str, *, recursive: bool = False): + """Add rules from a dir path. + + All rules from files are aggregated into a data structure representing a single rule file. + All group names are augmented with juju topology. + + Args: + path: either a rules file or a dir of rules files. + recursive: whether to read files recursively or not (no impact if `path` is a file). + + Raises: + InvalidAlertRulePathError: if the provided path is invalid. + """ + path = Path(path) # type: Path + if path.is_dir(): + self.alert_groups.extend(self._from_dir(path, recursive)) + elif path.is_file(): + self.alert_groups.extend(self._from_file(path.parent, path)) + else: + logger.debug("The alerts file does not exist: %s", path) + + def as_dict(self) -> dict: + """Return standard alert rules file in dict representation. + + Returns: + a dictionary containing a single list of alert rule groups. + The list of alert rule groups is provided as value of the + "groups" dictionary key. + """ + return {"groups": self.alert_groups} if self.alert_groups else {} + + +def _resolve_dir_against_charm_path(charm: CharmBase, *path_elements: str) -> str: + """Resolve the provided path items against the directory of the main file. + + Look up the directory of the `main.py` file being executed. This is normally + going to be the charm.py file of the charm including this library. Then, resolve + the provided path elements and, if the result path exists and is a directory, + return its absolute path; otherwise, raise en exception. + + Raises: + InvalidAlertRulePathError, if the path does not exist or is not a directory. + """ + charm_dir = Path(str(charm.charm_dir)) + if not charm_dir.exists() or not charm_dir.is_dir(): + # Operator Framework does not currently expose a robust + # way to determine the top level charm source directory + # that is consistent across deployed charms and unit tests + # Hence for unit tests the current working directory is used + # TODO: updated this logic when the following ticket is resolved + # https://github.com/canonical/operator/issues/643 + charm_dir = Path(os.getcwd()) + + alerts_dir_path = charm_dir.absolute().joinpath(*path_elements) + + if not alerts_dir_path.exists(): + raise InvalidAlertRulePathError(alerts_dir_path, "directory does not exist") + if not alerts_dir_path.is_dir(): + raise InvalidAlertRulePathError(alerts_dir_path, "is not a directory") + + return str(alerts_dir_path) + + +class NoRelationWithInterfaceFoundError(Exception): + """No relations with the given interface are found in the charm meta.""" + + def __init__(self, charm: CharmBase, relation_interface: Optional[str] = None): + self.charm = charm + self.relation_interface = relation_interface + self.message = ( + "No relations with interface '{}' found in the meta of the '{}' charm".format( + relation_interface, charm.meta.name + ) + ) + + super().__init__(self.message) + + +class MultipleRelationsWithInterfaceFoundError(Exception): + """Multiple relations with the given interface are found in the charm meta.""" + + def __init__(self, charm: CharmBase, relation_interface: str, relations: list): + self.charm = charm + self.relation_interface = relation_interface + self.relations = relations + self.message = ( + "Multiple relations with interface '{}' found in the meta of the '{}' charm.".format( + relation_interface, charm.meta.name + ) + ) + super().__init__(self.message) + + +class LokiPushApiEndpointDeparted(EventBase): + """Event emitted when Loki departed.""" + + +class LokiPushApiEndpointJoined(EventBase): + """Event emitted when Loki joined.""" + + +class LokiPushApiAlertRulesChanged(EventBase): + """Event emitted if there is a change in the alert rules.""" + + def __init__(self, handle, relation, relation_id, app=None, unit=None): + """Pretend we are almost like a RelationEvent. + + Fields to serialize: + { + "relation_name": , + "relation_id": , + "app_name": , + "unit_name": + } + + In this way, we can transparently use `RelationEvent.snapshot()` to pass + it back if we need to log it. + """ + super().__init__(handle) + self.relation = relation + self.relation_id = relation_id + self.app = app + self.unit = unit + + def snapshot(self) -> Dict: + """Save event information.""" + snapshot = {"relation_name": self.relation.name, "relation_id": self.relation.id} + if self.app: + snapshot["app_name"] = self.app.name + if self.unit: + snapshot["unit_name"] = self.unit.name + return snapshot + + def restore(self, snapshot: dict): + """Restore event information.""" + self.relation = self.framework.model.get_relation( + snapshot["relation_name"], snapshot["relation_id"] + ) + app_name = snapshot.get("app_name") + if app_name: + self.app = self.framework.model.get_app(app_name) + else: + self.app = None + unit_name = snapshot.get("unit_name") + if unit_name: + self.unit = self.framework.model.get_unit(unit_name) + else: + self.unit = None + + +class InvalidAlertRuleEvent(EventBase): + """Event emitted when alert rule files are not parsable. + + Enables us to set a clear status on the provider. + """ + + def __init__(self, handle, errors: str = "", valid: bool = False): + super().__init__(handle) + self.errors = errors + self.valid = valid + + def snapshot(self) -> Dict: + """Save alert rule information.""" + return { + "valid": self.valid, + "errors": self.errors, + } + + def restore(self, snapshot): + """Restore alert rule information.""" + self.valid = snapshot["valid"] + self.errors = snapshot["errors"] + + +class LokiPushApiEvents(ObjectEvents): + """Event descriptor for events raised by `LokiPushApiProvider`.""" + + loki_push_api_endpoint_departed = EventSource(LokiPushApiEndpointDeparted) + loki_push_api_endpoint_joined = EventSource(LokiPushApiEndpointJoined) + loki_push_api_alert_rules_changed = EventSource(LokiPushApiAlertRulesChanged) + alert_rule_status_changed = EventSource(InvalidAlertRuleEvent) + + +class LokiPushApiProvider(Object): + """A LokiPushApiProvider class.""" + + on = LokiPushApiEvents() + + def __init__( + self, + charm, + relation_name: str = DEFAULT_RELATION_NAME, + *, + port: Union[str, int] = 3100, + scheme: str = "http", + address: str = "localhost", + path: str = "loki/api/v1/push", + ): + """A Loki service provider. + + Args: + charm: a `CharmBase` instance that manages this + instance of the Loki service. + relation_name: an optional string name of the relation between `charm` + and the Loki charmed service. The default is "logging". + It is strongly advised not to change the default, so that people + deploying your charm will have a consistent experience with all + other charms that consume metrics endpoints. + port: an optional port of the Loki service (default is "3100"). + scheme: an optional scheme of the Loki API URL (default is "http"). + address: an optional address of the Loki service (default is "localhost"). + path: an optional path of the Loki API URL (default is "loki/api/v1/push") + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the `loki_push_api` relation + interface. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the `RelationRole.requires` + role. + """ + _validate_relation_by_interface_and_direction( + charm, relation_name, RELATION_INTERFACE_NAME, RelationRole.provides + ) + super().__init__(charm, relation_name) + self._charm = charm + self._relation_name = relation_name + self._tool = CosTool(self) + self.port = int(port) + self.scheme = scheme + self.address = address + self.path = path + + events = self._charm.on[relation_name] + self.framework.observe(self._charm.on.upgrade_charm, self._on_lifecycle_event) + self.framework.observe(events.relation_joined, self._on_logging_relation_joined) + self.framework.observe(events.relation_changed, self._on_logging_relation_changed) + self.framework.observe(events.relation_departed, self._on_logging_relation_departed) + self.framework.observe(events.relation_broken, self._on_logging_relation_broken) + + def _on_lifecycle_event(self, _): + # Upgrade event or other charm-level event + should_update = False + for relation in self._charm.model.relations[self._relation_name]: + # Don't accidentally flip a True result back. + should_update = should_update or self._process_logging_relation_changed(relation) + if should_update: + # We don't have a RelationEvent, so build it up by hand + first_rel = self._charm.model.relations[self._relation_name][0] + self.on.loki_push_api_alert_rules_changed.emit( + relation=first_rel, + relation_id=first_rel.id, + ) + + def _on_logging_relation_joined(self, event: RelationJoinedEvent): + """Set basic data on relation joins. + + Set the promtail binary URL location, which will not change, and anything + else which may be required, but is static.. + + Args: + event: a `CharmEvent` in response to which the consumer + charm must set its relation data. + """ + if self._charm.unit.is_leader(): + event.relation.data[self._charm.app].update(self._promtail_binary_url) + logger.debug("Saved promtail binary url: %s", self._promtail_binary_url) + + def _on_logging_relation_changed(self, event: HookEvent): + """Handle changes in related consumers. + + Anytime there are changes in the relation between Loki + and its consumers charms. + + Args: + event: a `CharmEvent` in response to which the consumer + charm must update its relation data. + """ + should_update = self._process_logging_relation_changed(event.relation) + if should_update: + self.on.loki_push_api_alert_rules_changed.emit( + relation=event.relation, + relation_id=event.relation.id, + app=self._charm.app, + unit=self._charm.unit, + ) + + def _on_logging_relation_broken(self, event: RelationBrokenEvent): + """Removes alert rules files when consumer charms left the relation with Loki. + + Args: + event: a `CharmEvent` in response to which the Loki + charm must update its relation data. + """ + self.on.loki_push_api_alert_rules_changed.emit( + relation=event.relation, + relation_id=event.relation.id, + app=self._charm.app, + unit=self._charm.unit, + ) + + def _on_logging_relation_departed(self, event: RelationDepartedEvent): + """Removes alert rules files when consumer charms left the relation with Loki. + + Args: + event: a `CharmEvent` in response to which the Loki + charm must update its relation data. + """ + self.on.loki_push_api_alert_rules_changed.emit( + relation=event.relation, + relation_id=event.relation.id, + app=self._charm.app, + unit=self._charm.unit, + ) + + def _should_update_alert_rules(self, relation) -> bool: + """Determine whether alert rules should be regenerated. + + If there are alert rules in the relation data bag, tell the charm + whether to regenerate them based on the boolean returned here. + """ + if relation.data.get(relation.app).get("alert_rules", None) is not None: + return True + return False + + def _process_logging_relation_changed(self, relation: Relation) -> bool: + """Handle changes in related consumers. + + Anytime there are changes in relations between Loki + and its consumers charms, Loki set the `loki_push_api` + into the relation data. Set the endpoint building + appropriately, and if there are alert rules present in + the relation, let the caller know. + Besides Loki generates alert rules files based what + consumer charms forwards, + + Args: + relation: the `Relation` instance to update. + + Returns: + A boolean indicating whether an event should be emitted, so we + only emit one on lifecycle events + """ + relation.data[self._charm.unit]["public_address"] = socket.getfqdn() or "" + self.update_endpoint(relation=relation) + return self._should_update_alert_rules(relation) + + @property + def _promtail_binary_url(self) -> dict: + """URL from which Promtail binary can be downloaded.""" + # construct promtail binary url paths from parts + promtail_binaries = {} + for arch, info in PROMTAIL_BINARIES.items(): + info["url"] = "{}/promtail-{}/{}.gz".format( + PROMTAIL_BASE_URL, PROMTAIL_VERSION, info["filename"] + ) + promtail_binaries[arch] = info + + return {"promtail_binary_zip_url": json.dumps(promtail_binaries)} + + def update_endpoint(self, url: str = "", relation: Optional[Relation] = None) -> None: + """Triggers programmatically the update of endpoint in unit relation data. + + This method should be used when the charm relying on this library needs + to update the relation data in response to something occurring outside + the `logging` relation lifecycle, e.g., in case of a + host address change because the charmed operator becomes connected to an + Ingress after the `logging` relation is established. + + Args: + url: An optional url value to update relation data. + relation: An optional instance of `class:ops.model.Relation` to update. + """ + # if no relation is specified update all of them + if not relation: + if not self._charm.model.relations.get(self._relation_name): + return + + relations_list = self._charm.model.relations.get(self._relation_name) + else: + relations_list = [relation] + + endpoint = self._endpoint(url or self._url) + + for relation in relations_list: + relation.data[self._charm.unit].update({"endpoint": json.dumps(endpoint)}) + + logger.debug("Saved endpoint in unit relation data") + + @property + def _url(self) -> str: + """Get local Loki Push API url. + + Return url to loki, including port number, but without the endpoint subpath. + """ + return "http://{}:{}".format(socket.getfqdn(), self.port) + + def _endpoint(self, url) -> dict: + """Get Loki push API endpoint for a given url. + + Args: + url: A loki unit URL. + + Returns: str + """ + endpoint = "/loki/api/v1/push" + return {"url": url.rstrip("/") + endpoint} + + @property + def alerts(self) -> dict: # noqa: C901 + """Fetch alerts for all relations. + + A Loki alert rules file consists of a list of "groups". Each + group consists of a list of alerts (`rules`) that are sequentially + executed. This method returns all the alert rules provided by each + related metrics provider charm. These rules may be used to generate a + separate alert rules file for each relation since the returned list + of alert groups are indexed by relation ID. Also for each relation ID + associated scrape metadata such as Juju model, UUID and application + name are provided so a unique name may be generated for the rules + file. For each relation the structure of data returned is a dictionary + with four keys + + - groups + - model + - model_uuid + - application + + The value of the `groups` key is such that it may be used to generate + a Loki alert rules file directly using `yaml.dump` but the + `groups` key itself must be included as this is required by Loki, + for example as in `yaml.dump({"groups": alerts["groups"]})`. + + Currently only accepts a list of rules and these + rules are all placed into a single group, even though Loki itself + allows for multiple groups within a single alert rules file. + + Returns: + a dictionary of alert rule groups and associated scrape + metadata indexed by relation ID. + """ + alerts = {} # type: Dict[str, dict] # mapping b/w juju identifiers and alert rule files + for relation in self._charm.model.relations[self._relation_name]: + if not relation.units or not relation.app: + continue + + alert_rules = json.loads(relation.data[relation.app].get("alert_rules", "{}")) + if not alert_rules: + continue + + alert_rules = self._inject_alert_expr_labels(alert_rules) + + identifier, topology = self._get_identifier_by_alert_rules(alert_rules) + if not topology: + try: + metadata = json.loads(relation.data[relation.app]["metadata"]) + identifier = JujuTopology.from_dict(metadata).identifier + alerts[identifier] = self._tool.apply_label_matchers(alert_rules) # type: ignore + + except KeyError as e: + logger.debug( + "Relation %s has no 'metadata': %s", + relation.id, + e, + ) + + if not identifier: + logger.error( + "Alert rules were found but no usable group or identifier was present." + ) + continue + + _, errmsg = self._tool.validate_alert_rules(alert_rules) + if errmsg: + relation.data[self._charm.app]["event"] = json.dumps({"errors": errmsg}) + continue + + alerts[identifier] = alert_rules + + return alerts + + def _get_identifier_by_alert_rules( + self, rules: dict + ) -> Tuple[Union[str, None], Union[JujuTopology, None]]: + """Determine an appropriate dict key for alert rules. + + The key is used as the filename when writing alerts to disk, so the structure + and uniqueness is important. + + Args: + rules: a dict of alert rules + Returns: + A tuple containing an identifier, if found, and a JujuTopology, if it could + be constructed. + """ + if "groups" not in rules: + logger.debug("No alert groups were found in relation data") + return None, None + + # Construct an ID based on what's in the alert rules if they have labels + for group in rules["groups"]: + try: + labels = group["rules"][0]["labels"] + topology = JujuTopology( + # Don't try to safely get required constructor fields. There's already + # a handler for KeyErrors + model_uuid=labels["juju_model_uuid"], + model=labels["juju_model"], + application=labels["juju_application"], + unit=labels.get("juju_unit", ""), + charm_name=labels.get("juju_charm", ""), + ) + return topology.identifier, topology + except KeyError: + logger.debug("Alert rules were found but no usable labels were present") + continue + + logger.warning( + "No labeled alert rules were found, and no 'scrape_metadata' " + "was available. Using the alert group name as filename." + ) + try: + for group in rules["groups"]: + return group["name"], None + except KeyError: + logger.debug("No group name was found to use as identifier") + + return None, None + + def _inject_alert_expr_labels(self, rules: Dict[str, Any]) -> Dict[str, Any]: + """Iterate through alert rules and inject topology into expressions. + + Args: + rules: a dict of alert rules + """ + if "groups" not in rules: + return rules + + modified_groups = [] + for group in rules["groups"]: + # Copy off rules, so we don't modify an object we're iterating over + rules_copy = group["rules"] + for idx, rule in enumerate(rules_copy): + labels = rule.get("labels") + + if labels: + try: + topology = JujuTopology( + # Don't try to safely get required constructor fields. There's already + # a handler for KeyErrors + model_uuid=labels["juju_model_uuid"], + model=labels["juju_model"], + application=labels["juju_application"], + unit=labels.get("juju_unit", ""), + charm_name=labels.get("juju_charm", ""), + ) + + # Inject topology and put it back in the list + rule["expr"] = self._tool.inject_label_matchers( + re.sub(r"%%juju_topology%%,?", "", rule["expr"]), + topology.label_matcher_dict, + ) + except KeyError: + # Some required JujuTopology key is missing. Just move on. + pass + + group["rules"][idx] = rule + + modified_groups.append(group) + + rules["groups"] = modified_groups + return rules + + +class ConsumerBase(Object): + """Consumer's base class.""" + + def __init__( + self, + charm: CharmBase, + relation_name: str = DEFAULT_RELATION_NAME, + alert_rules_path: str = DEFAULT_ALERT_RULES_RELATIVE_PATH, + recursive: bool = False, + skip_alert_topology_labeling: bool = False, + ): + super().__init__(charm, relation_name) + self._charm = charm + self._relation_name = relation_name + self.topology = JujuTopology.from_charm(charm) + + try: + alert_rules_path = _resolve_dir_against_charm_path(charm, alert_rules_path) + except InvalidAlertRulePathError as e: + logger.debug( + "Invalid Loki alert rules folder at %s: %s", + e.alert_rules_absolute_path, + e.message, + ) + self._alert_rules_path = alert_rules_path + self._skip_alert_topology_labeling = skip_alert_topology_labeling + + self._recursive = recursive + + def _handle_alert_rules(self, relation): + if not self._charm.unit.is_leader(): + return + + alert_rules = ( + AlertRules(None) if self._skip_alert_topology_labeling else AlertRules(self.topology) + ) + alert_rules.add_path(self._alert_rules_path, recursive=self._recursive) + alert_rules_as_dict = alert_rules.as_dict() + + relation.data[self._charm.app]["metadata"] = json.dumps(self.topology.as_dict()) + relation.data[self._charm.app]["alert_rules"] = json.dumps( + alert_rules_as_dict, + sort_keys=True, # sort, to prevent unnecessary relation_changed events + ) + + @property + def loki_endpoints(self) -> List[dict]: + """Fetch Loki Push API endpoints sent from LokiPushApiProvider through relation data. + + Returns: + A list of dictionaries with Loki Push API endpoints, for instance: + [ + {"url": "http://loki1:3100/loki/api/v1/push"}, + {"url": "http://loki2:3100/loki/api/v1/push"}, + ] + """ + endpoints = [] # type: list + + for relation in self._charm.model.relations[self._relation_name]: + for unit in relation.units: + if unit.app == self._charm.app: + # This is a peer unit + continue + + endpoint = relation.data[unit].get("endpoint") + if endpoint: + deserialized_endpoint = json.loads(endpoint) + endpoints.append(deserialized_endpoint) + + return endpoints + + +class LokiPushApiConsumer(ConsumerBase): + """Loki Consumer class.""" + + on = LokiPushApiEvents() + + def __init__( + self, + charm: CharmBase, + relation_name: str = DEFAULT_RELATION_NAME, + alert_rules_path: str = DEFAULT_ALERT_RULES_RELATIVE_PATH, + recursive: bool = True, + skip_alert_topology_labeling: bool = False, + ): + """Construct a Loki charm client. + + The `LokiPushApiConsumer` object provides configurations to a Loki client charm, such as + the Loki API endpoint to push logs. It is intended for workloads that can speak + loki_push_api (https://grafana.com/docs/loki/latest/api/#push-log-entries-to-loki), such + as grafana-agent. + (If you only need to forward a few workload log files, then use LogProxyConsumer.) + + `LokiPushApiConsumer` can be instantiated as follows: + + self._loki_consumer = LokiPushApiConsumer(self) + + Args: + charm: a `CharmBase` object that manages this `LokiPushApiConsumer` object. + Typically, this is `self` in the instantiating class. + relation_name: the string name of the relation interface to look up. + If `charm` has exactly one relation with this interface, the relation's + name is returned. If none or multiple relations with the provided interface + are found, this method will raise either a NoRelationWithInterfaceFoundError or + MultipleRelationsWithInterfaceFoundError exception, respectively. + alert_rules_path: a string indicating a path where alert rules can be found + recursive: Whether to scan for rule files recursively. + skip_alert_topology_labeling: whether to skip the alert topology labeling. + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the `loki_push_api` relation + interface. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the `RelationRole.provides` + role. + + Emits: + loki_push_api_endpoint_joined: This event is emitted when the relation between the + Charmed Operator that instantiates `LokiPushApiProvider` (Loki charm for instance) + and the Charmed Operator that instantiates `LokiPushApiConsumer` is established. + loki_push_api_endpoint_departed: This event is emitted when the relation between the + Charmed Operator that implements `LokiPushApiProvider` (Loki charm for instance) + and the Charmed Operator that implements `LokiPushApiConsumer` is removed. + loki_push_api_alert_rules_error: This event is emitted when an invalid alert rules + file is encountered or if `alert_rules_path` is empty. + """ + _validate_relation_by_interface_and_direction( + charm, relation_name, RELATION_INTERFACE_NAME, RelationRole.requires + ) + super().__init__( + charm, relation_name, alert_rules_path, recursive, skip_alert_topology_labeling + ) + events = self._charm.on[relation_name] + self.framework.observe(self._charm.on.upgrade_charm, self._on_lifecycle_event) + self.framework.observe(events.relation_joined, self._on_logging_relation_joined) + self.framework.observe(events.relation_changed, self._on_logging_relation_changed) + self.framework.observe(events.relation_departed, self._on_logging_relation_departed) + + def _on_lifecycle_event(self, _: HookEvent): + """Update require relation data on charm upgrades and other lifecycle events. + + Args: + event: a `CharmEvent` in response to which the consumer + charm must update its relation data. + """ + # Upgrade event or other charm-level event + self._reinitialize_alert_rules() + self.on.loki_push_api_endpoint_joined.emit() + + def _on_logging_relation_joined(self, event: RelationJoinedEvent): + """Handle changes in related consumers. + + Update relation data and emit events when a relation is established. + + Args: + event: a `CharmEvent` in response to which the consumer + charm must update its relation data. + + Emits: + loki_push_api_endpoint_joined: Once the relation is established, this event is emitted. + loki_push_api_alert_rules_error: This event is emitted when an invalid alert rules + file is encountered or if `alert_rules_path` is empty. + """ + # Alert rules will not change over the lifecycle of a charm, and do not need to be + # constantly set on every relation_changed event. Leave them here. + self._handle_alert_rules(event.relation) + self.on.loki_push_api_endpoint_joined.emit() + + def _on_logging_relation_changed(self, event: RelationEvent): + """Handle changes in related consumers. + + Anytime there are changes in the relation between Loki + and its consumers charms. + + Args: + event: a `CharmEvent` in response to which the consumer + charm must update its relation data. + + Emits: + loki_push_api_endpoint_joined: Once the relation is established, this event is emitted. + loki_push_api_alert_rules_error: This event is emitted when an invalid alert rules + file is encountered or if `alert_rules_path` is empty. + """ + if self._charm.unit.is_leader(): + ev = json.loads(event.relation.data[event.app].get("event", "{}")) + + if ev: + valid = bool(ev.get("valid", True)) + errors = ev.get("errors", "") + + if valid and not errors: + self.on.alert_rule_status_changed.emit(valid=valid) + else: + self.on.alert_rule_status_changed.emit(valid=valid, errors=errors) + + self.on.loki_push_api_endpoint_joined.emit() + + def _reinitialize_alert_rules(self): + """Reloads alert rules and updates all relations.""" + for relation in self._charm.model.relations[self._relation_name]: + self._handle_alert_rules(relation) + + def _process_logging_relation_changed(self, relation: Relation): + self._handle_alert_rules(relation) + self.on.loki_push_api_endpoint_joined.emit() + + def _on_logging_relation_departed(self, _: RelationEvent): + """Handle departures in related providers. + + Anytime there are departures in relations between the consumer charm and Loki + the consumer charm is informed, through a `LokiPushApiEndpointDeparted` event. + The consumer charm can then choose to update its configuration. + """ + # Provide default to avoid throwing, as in some complicated scenarios with + # upgrades and hook failures we might not have data in the storage + self.on.loki_push_api_endpoint_departed.emit() + + +class ContainerNotFoundError(Exception): + """Raised if the specified container does not exist.""" + + def __init__(self): + msg = "The specified container does not exist." + self.message = msg + + super().__init__(self.message) + + +class MultipleContainersFoundError(Exception): + """Raised if no container name is passed but multiple containers are present.""" + + def __init__(self): + msg = ( + "No 'container_name' parameter has been specified; since this Charmed Operator" + " is has multiple containers, container_name must be specified for the container" + " to get logs from." + ) + self.message = msg + + super().__init__(self.message) + + +class PromtailDigestError(EventBase): + """Event emitted when there is an error with Promtail initialization.""" + + def __init__(self, handle, message): + super().__init__(handle) + self.message = message + + def snapshot(self): + """Save message information.""" + return {"message": self.message} + + def restore(self, snapshot): + """Restore message information.""" + self.message = snapshot["message"] + + +class LogProxyEndpointDeparted(EventBase): + """Event emitted when a Log Proxy has departed.""" + + +class LogProxyEndpointJoined(EventBase): + """Event emitted when a Log Proxy joins.""" + + +class LogProxyEvents(ObjectEvents): + """Event descriptor for events raised by `LogProxyConsumer`.""" + + promtail_digest_error = EventSource(PromtailDigestError) + log_proxy_endpoint_departed = EventSource(LogProxyEndpointDeparted) + log_proxy_endpoint_joined = EventSource(LogProxyEndpointJoined) + + +class LogProxyConsumer(ConsumerBase): + """LogProxyConsumer class. + + The `LogProxyConsumer` object provides a method for attaching `promtail` to + a workload in order to generate structured logging data from applications + which traditionally log to syslog or do not have native Loki integration. + The `LogProxyConsumer` can be instantiated as follows: + + self._log_proxy_consumer = LogProxyConsumer(self, log_files=["/var/log/messages"]) + + Args: + charm: a `CharmBase` object that manages this `LokiPushApiConsumer` object. + Typically, this is `self` in the instantiating class. + log_files: a list of log files to monitor with Promtail. + relation_name: the string name of the relation interface to look up. + If `charm` has exactly one relation with this interface, the relation's + name is returned. If none or multiple relations with the provided interface + are found, this method will raise either a NoRelationWithInterfaceFoundError or + MultipleRelationsWithInterfaceFoundError exception, respectively. + enable_syslog: Whether to enable syslog integration. + syslog_port: The port syslog is attached to. + alert_rules_path: an optional path for the location of alert rules + files. Defaults to "./src/loki_alert_rules", + resolved from the directory hosting the charm entry file. + The alert rules are automatically updated on charm upgrade. + recursive: Whether to scan for rule files recursively. + container_name: An optional container name to inject the payload into. + promtail_resource_name: An optional promtail resource name from metadata + if it has been modified and attached + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the `loki_push_api` relation + interface. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the `RelationRole.provides` + role. + """ + + on = LogProxyEvents() + + def __init__( + self, + charm, + log_files: Optional[Union[List[str], str]] = None, + relation_name: str = DEFAULT_LOG_PROXY_RELATION_NAME, + enable_syslog: bool = False, + syslog_port: int = 1514, + alert_rules_path: str = DEFAULT_ALERT_RULES_RELATIVE_PATH, + recursive: bool = False, + container_name: str = "", + promtail_resource_name: Optional[str] = None, + ): + super().__init__(charm, relation_name, alert_rules_path, recursive) + self._charm = charm + self._relation_name = relation_name + self._container = self._get_container(container_name) + self._container_name = self._get_container_name(container_name) + + if not log_files: + log_files = [] + elif isinstance(log_files, str): + log_files = [log_files] + elif not isinstance(log_files, list) or not all((isinstance(x, str) for x in log_files)): + raise TypeError("The 'log_files' argument must be a list of strings.") + self._log_files = log_files + + self._syslog_port = syslog_port + self._is_syslog = enable_syslog + self.topology = JujuTopology.from_charm(charm) + self._promtail_resource_name = promtail_resource_name or "promtail-bin" + + # architecture used for promtail binary + arch = platform.processor() + self._arch = "amd64" if arch == "x86_64" else arch + + events = self._charm.on[relation_name] + self.framework.observe(events.relation_created, self._on_relation_created) + self.framework.observe(events.relation_changed, self._on_relation_changed) + self.framework.observe(events.relation_departed, self._on_relation_departed) + # turn the container name to a valid Python identifier + snake_case_container_name = self._container_name.replace("-", "_") + self.framework.observe( + getattr(self._charm.on, "{}_pebble_ready".format(snake_case_container_name)), + self._on_pebble_ready, + ) + + def _on_pebble_ready(self, _: WorkloadEvent): + """Event handler for `pebble_ready`.""" + if self.model.relations[self._relation_name]: + self._setup_promtail() + + def _on_relation_created(self, _: RelationCreatedEvent) -> None: + """Event handler for `relation_created`.""" + if not self._container.can_connect(): + return + self._setup_promtail() + + def _on_relation_changed(self, event: RelationEvent) -> None: + """Event handler for `relation_changed`. + + Args: + event: The event object `RelationChangedEvent`. + """ + self._handle_alert_rules(event.relation) + + if self._charm.unit.is_leader(): + ev = json.loads(event.relation.data[event.app].get("event", "{}")) + + if ev: + valid = bool(ev.get("valid", True)) + errors = ev.get("errors", "") + + if valid and not errors: + self.on.alert_rule_status_changed.emit(valid=valid) + else: + self.on.alert_rule_status_changed.emit(valid=valid, errors=errors) + + if not self._container.can_connect(): + return + if self.model.relations[self._relation_name]: + if "promtail" not in self._container.get_plan().services: + self._setup_promtail() + return + + new_config = self._promtail_config + if new_config != self._current_config: + self._container.push( + WORKLOAD_CONFIG_PATH, yaml.safe_dump(new_config), make_dirs=True + ) + + # Loki may send endpoints late. Don't necessarily start, there may be + # no clients + if new_config["clients"]: + self._container.restart(WORKLOAD_SERVICE_NAME) + self.on.log_proxy_endpoint_joined.emit() + else: + self.on.promtail_digest_error.emit("No promtail client endpoints available!") + + def _on_relation_departed(self, _: RelationEvent) -> None: + """Event handler for `relation_departed`. + + Args: + event: The event object `RelationDepartedEvent`. + """ + if not self._container.can_connect(): + return + if not self._charm.model.relations[self._relation_name]: + self._container.stop(WORKLOAD_SERVICE_NAME) + return + + new_config = self._promtail_config + if new_config != self._current_config: + self._container.push(WORKLOAD_CONFIG_PATH, yaml.safe_dump(new_config), make_dirs=True) + + if new_config["clients"]: + self._container.restart(WORKLOAD_SERVICE_NAME) + else: + self._container.stop(WORKLOAD_SERVICE_NAME) + self.on.log_proxy_endpoint_departed.emit() + + def _get_container(self, container_name: str = "") -> Container: + """Gets a single container by name or using the only container running in the Pod. + + If there is more than one container in the Pod a `PromtailDigestError` is emitted. + + Args: + container_name: The container name. + + Returns: + A `ops.model.Container` object representing the container. + + Emits: + PromtailDigestError, if there was a problem obtaining a container. + """ + try: + container_name = self._get_container_name(container_name) + return self._charm.unit.get_container(container_name) + except (MultipleContainersFoundError, ContainerNotFoundError, ModelError) as e: + msg = str(e) + logger.warning(msg) + self.on.promtail_digest_error.emit(msg) + + def _get_container_name(self, container_name: str = "") -> str: + """Helper function for getting/validating a container name. + + Args: + container_name: The container name to be validated (optional). + + Returns: + container_name: The same container_name that was passed (if it exists) or the only + container name that is present (if no container_name was passed). + + Raises: + ContainerNotFoundError, if container_name does not exist. + MultipleContainersFoundError, if container_name was not provided but multiple + containers are present. + """ + containers = dict(self._charm.model.unit.containers) + if len(containers) == 0: + raise ContainerNotFoundError + + if not container_name: + # container_name was not provided - will get it ourselves, if it is the only one + if len(containers) > 1: + raise MultipleContainersFoundError + + # Get the first key in the containers' dict. + # Need to "cast", otherwise: + # error: Incompatible return value type (got "Optional[str]", expected "str") + container_name = cast(str, next(iter(containers.keys()))) + + elif container_name not in containers: + raise ContainerNotFoundError + + return container_name + + def _add_pebble_layer(self, workload_binary_path: str) -> None: + """Adds Pebble layer that manages Promtail service in Workload container. + + Args: + workload_binary_path: string providing path to promtail binary in workload container. + """ + pebble_layer = { + "summary": "promtail layer", + "description": "pebble config layer for promtail", + "services": { + WORKLOAD_SERVICE_NAME: { + "override": "replace", + "summary": WORKLOAD_SERVICE_NAME, + "command": "{} {}".format(workload_binary_path, self._cli_args), + "startup": "disabled", + } + }, + } + self._container.add_layer(self._container_name, pebble_layer, combine=True) + + def _create_directories(self) -> None: + """Creates the directories for Promtail binary and config file.""" + self._container.make_dir(path=WORKLOAD_BINARY_DIR, make_parents=True) + self._container.make_dir(path=WORKLOAD_CONFIG_DIR, make_parents=True) + + def _obtain_promtail(self, promtail_info: dict) -> None: + """Obtain promtail binary from an attached resource or download it. + + Args: + promtail_info: dictionary containing information about promtail binary + that must be used. The dictionary must have three keys + - "filename": filename of promtail binary + - "zipsha": sha256 sum of zip file of promtail binary + - "binsha": sha256 sum of unpacked promtail binary + """ + workload_binary_path = os.path.join(WORKLOAD_BINARY_DIR, promtail_info["filename"]) + if self._promtail_attached_as_resource: + self._push_promtail_if_attached(workload_binary_path) + return + + if self._promtail_must_be_downloaded(promtail_info): + self._download_and_push_promtail_to_workload(promtail_info) + else: + binary_path = os.path.join(BINARY_DIR, promtail_info["filename"]) + self._push_binary_to_workload(binary_path, workload_binary_path) + + def _push_binary_to_workload(self, binary_path: str, workload_binary_path: str) -> None: + """Push promtail binary into workload container. + + Args: + binary_path: path in charm container from which promtail binary is read. + workload_binary_path: path in workload container to which promtail binary is pushed. + """ + with open(binary_path, "rb") as f: + self._container.push(workload_binary_path, f, permissions=0o755, make_dirs=True) + logger.debug("The promtail binary file has been pushed to the workload container.") + + @property + def _promtail_attached_as_resource(self) -> bool: + """Checks whether Promtail binary is attached to the charm or not. + + Returns: + a boolean representing whether Promtail binary is attached as a resource or not. + """ + try: + self._charm.model.resources.fetch(self._promtail_resource_name) + return True + except ModelError: + return False + except NameError as e: + if "invalid resource name" in str(e): + return False + raise + + def _push_promtail_if_attached(self, workload_binary_path: str) -> bool: + """Checks whether Promtail binary is attached to the charm or not. + + Args: + workload_binary_path: string specifying expected path of promtail + in workload container + + Returns: + a boolean representing whether Promtail binary is attached or not. + """ + logger.info("Promtail binary file has been obtained from an attached resource.") + resource_path = self._charm.model.resources.fetch(self._promtail_resource_name) + self._push_binary_to_workload(resource_path, workload_binary_path) + return True + + def _promtail_must_be_downloaded(self, promtail_info: dict) -> bool: + """Checks whether promtail binary must be downloaded or not. + + Args: + promtail_info: dictionary containing information about promtail binary + that must be used. The dictionary must have three keys + - "filename": filename of promtail binary + - "zipsha": sha256 sum of zip file of promtail binary + - "binsha": sha256 sum of unpacked promtail binary + + Returns: + a boolean representing whether Promtail binary must be downloaded or not. + """ + binary_path = os.path.join(BINARY_DIR, promtail_info["filename"]) + if not self._is_promtail_binary_in_charm(binary_path): + return True + + if not self._sha256sums_matches(binary_path, promtail_info["binsha"]): + return True + + logger.debug("Promtail binary file is already in the the charm container.") + return False + + def _sha256sums_matches(self, file_path: str, sha256sum: str) -> bool: + """Checks whether a file's sha256sum matches or not with a specific sha256sum. + + Args: + file_path: A string representing the files' patch. + sha256sum: The sha256sum against which we want to verify. + + Returns: + a boolean representing whether a file's sha256sum matches or not with + a specific sha256sum. + """ + try: + with open(file_path, "rb") as f: + file_bytes = f.read() + result = sha256(file_bytes).hexdigest() + + if result != sha256sum: + msg = "File sha256sum mismatch, expected:'{}' but got '{}'".format( + sha256sum, result + ) + logger.debug(msg) + return False + + return True + except (APIError, FileNotFoundError): + msg = "File: '{}' could not be opened".format(file_path) + logger.error(msg) + return False + + def _is_promtail_binary_in_charm(self, binary_path: str) -> bool: + """Check if Promtail binary is already stored in charm container. + + Args: + binary_path: string path of promtail binary to check + + Returns: + a boolean representing whether Promtail is present or not. + """ + return True if Path(binary_path).is_file() else False + + def _download_and_push_promtail_to_workload(self, promtail_info: dict) -> None: + """Downloads a Promtail zip file and pushes the binary to the workload. + + Args: + promtail_info: dictionary containing information about promtail binary + that must be used. The dictionary must have three keys + - "filename": filename of promtail binary + - "zipsha": sha256 sum of zip file of promtail binary + - "binsha": sha256 sum of unpacked promtail binary + """ + with request.urlopen(promtail_info["url"]) as r: + file_bytes = r.read() + file_path = os.path.join(BINARY_DIR, promtail_info["filename"] + ".gz") + with open(file_path, "wb") as f: + f.write(file_bytes) + logger.info( + "Promtail binary zip file has been downloaded and stored in: %s", + file_path, + ) + + decompressed_file = GzipFile(fileobj=BytesIO(file_bytes)) + binary_path = os.path.join(BINARY_DIR, promtail_info["filename"]) + with open(binary_path, "wb") as outfile: + outfile.write(decompressed_file.read()) + logger.debug("Promtail binary file has been downloaded.") + + workload_binary_path = os.path.join(WORKLOAD_BINARY_DIR, promtail_info["filename"]) + self._push_binary_to_workload(binary_path, workload_binary_path) + + @property + def _cli_args(self) -> str: + """Return the cli arguments to pass to promtail. + + Returns: + The arguments as a string + """ + return "-config.file={}".format(WORKLOAD_CONFIG_PATH) + + @property + def _current_config(self) -> dict: + """Property that returns the current Promtail configuration. + + Returns: + A dict containing Promtail configuration. + """ + if not self._container.can_connect(): + logger.debug("Could not connect to promtail container!") + return {} + try: + raw_current = self._container.pull(WORKLOAD_CONFIG_PATH).read() + return yaml.safe_load(raw_current) + except (ProtocolError, PathError) as e: + logger.warning( + "Could not check the current promtail configuration due to " + "a failure in retrieving the file: %s", + e, + ) + return {} + + @property + def _promtail_config(self) -> dict: + """Generates the config file for Promtail.""" + config = {"clients": self._clients_list()} + config.update(self._server_config()) + config.update(self._positions()) + config.update(self._scrape_configs()) + return config + + def _clients_list(self) -> list: + """Generates a list of clients for use in the promtail config. + + Returns: + A list of endpoints + """ + return self.loki_endpoints + + def _server_config(self) -> dict: + """Generates the server section of the Promtail config file. + + Returns: + A dict representing the `server` section. + """ + return { + "server": { + "http_listen_port": HTTP_LISTEN_PORT, + "grpc_listen_port": GRPC_LISTEN_PORT, + } + } + + def _positions(self) -> dict: + """Generates the positions section of the Promtail config file. + + Returns: + A dict representing the `positions` section. + """ + return {"positions": {"filename": WORKLOAD_POSITIONS_PATH}} + + def _scrape_configs(self) -> dict: + """Generates the scrape_configs section of the Promtail config file. + + Returns: + A dict representing the `scrape_configs` section. + """ + job_name = "juju_{}".format(self.topology.identifier) + + # The new JujuTopology doesn't include unit, but LogProxyConsumer should have it + common_labels = { + "juju_{}".format(k): v + for k, v in self.topology.as_dict(remapped_keys={"charm_name": "charm"}).items() + } + scrape_configs = [] + + # Files config + labels = common_labels.copy() + labels.update( + { + "job": job_name, + "__path__": "", + } + ) + config = {"targets": ["localhost"], "labels": labels} + scrape_config = { + "job_name": "system", + "static_configs": self._generate_static_configs(config), + } + scrape_configs.append(scrape_config) + + # Syslog config + if self._is_syslog: + relabel_mappings = [ + "severity", + "facility", + "hostname", + "app_name", + "proc_id", + "msg_id", + ] + syslog_labels = common_labels.copy() + syslog_labels.update({"job": "{}_syslog".format(job_name)}) + syslog_config = { + "job_name": "syslog", + "syslog": { + "listen_address": "127.0.0.1:{}".format(self._syslog_port), + "label_structured_data": True, + "labels": syslog_labels, + }, + "relabel_configs": [ + {"source_labels": ["__syslog_message_{}".format(val)], "target_label": val} + for val in relabel_mappings + ] + + [{"action": "labelmap", "regex": "__syslog_message_sd_(.+)"}], + } + scrape_configs.append(syslog_config) # type: ignore + + return {"scrape_configs": scrape_configs} + + def _generate_static_configs(self, config: dict) -> list: + """Generates static_configs section. + + Returns: + - a list of dictionaries representing static_configs section + """ + static_configs = [] + + for _file in self._log_files: + conf = deepcopy(config) + conf["labels"]["__path__"] = _file + static_configs.append(conf) + + return static_configs + + def _setup_promtail(self) -> None: + # Use the first + relations = self._charm.model.relations[self._relation_name] + if len(relations) > 1: + logger.debug( + "Multiple log_proxy relations. Getting Promtail from application {}".format( + relations[0].app.name + ) + ) + relation = relations[0] + promtail_binaries = json.loads( + relation.data[relation.app].get("promtail_binary_zip_url", "{}") + ) + if not promtail_binaries: + return + + if not self._is_promtail_installed(promtail_binaries[self._arch]): + try: + self._obtain_promtail(promtail_binaries[self._arch]) + except HTTPError as e: + msg = "Promtail binary couldn't be downloaded - {}".format(str(e)) + logger.warning(msg) + self.on.promtail_digest_error.emit(msg) + return + + workload_binary_path = os.path.join( + WORKLOAD_BINARY_DIR, promtail_binaries[self._arch]["filename"] + ) + + self._create_directories() + self._container.push( + WORKLOAD_CONFIG_PATH, yaml.safe_dump(self._promtail_config), make_dirs=True + ) + + self._add_pebble_layer(workload_binary_path) + + if self._current_config.get("clients"): + try: + self._container.restart(WORKLOAD_SERVICE_NAME) + except ChangeError as e: + self.on.promtail_digest_error.emit(str(e)) + else: + self.on.log_proxy_endpoint_joined.emit() + else: + self.on.promtail_digest_error.emit("No promtail client endpoints available!") + + def _is_promtail_installed(self, promtail_info: dict) -> bool: + """Determine if promtail has already been installed to the container. + + Args: + promtail_info: dictionary containing information about promtail binary + that must be used. The dictionary must at least contain a key + "filename" giving the name of promtail binary + """ + workload_binary_path = "{}/{}".format(WORKLOAD_BINARY_DIR, promtail_info["filename"]) + try: + self._container.list_files(workload_binary_path) + except (APIError, FileNotFoundError): + return False + return True + + @property + def syslog_port(self) -> str: + """Gets the port on which promtail is listening for syslog. + + Returns: + A str representing the port + """ + return str(self._syslog_port) + + @property + def rsyslog_config(self) -> str: + """Generates a config line for use with rsyslog. + + Returns: + The rsyslog config line as a string + """ + return 'action(type="omfwd" protocol="tcp" target="127.0.0.1" port="{}" Template="RSYSLOG_SyslogProtocol23Format" TCP_Framing="octet-counted")'.format( + self._syslog_port + ) + + +class CosTool: + """Uses cos-tool to inject label matchers into alert rule expressions and validate rules.""" + + _path = None + _disabled = False + + def __init__(self, charm): + self._charm = charm + + @property + def path(self): + """Lazy lookup of the path of cos-tool.""" + if self._disabled: + return None + if not self._path: + self._path = self._get_tool_path() + if not self._path: + logger.debug("Skipping injection of juju topology as label matchers") + self._disabled = True + return self._path + + def apply_label_matchers(self, rules) -> dict: + """Will apply label matchers to the expression of all alerts in all supplied groups.""" + if not self.path: + return rules + for group in rules["groups"]: + rules_in_group = group.get("rules", []) + for rule in rules_in_group: + topology = {} + # if the user for some reason has provided juju_unit, we'll need to honor it + # in most cases, however, this will be empty + for label in [ + "juju_model", + "juju_model_uuid", + "juju_application", + "juju_charm", + "juju_unit", + ]: + if label in rule["labels"]: + topology[label] = rule["labels"][label] + + rule["expr"] = self.inject_label_matchers(rule["expr"], topology) + return rules + + def validate_alert_rules(self, rules: dict) -> Tuple[bool, str]: + """Will validate correctness of alert rules, returning a boolean and any errors.""" + if not self.path: + logger.debug("`cos-tool` unavailable. Not validating alert correctness.") + return True, "" + + with tempfile.TemporaryDirectory() as tmpdir: + rule_path = Path(tmpdir + "/validate_rule.yaml") + + # Smash "our" rules format into what upstream actually uses, which is more like: + # + # groups: + # - name: foo + # rules: + # - alert: SomeAlert + # expr: up + # - alert: OtherAlert + # expr: up + transformed_rules = {"groups": []} # type: ignore + for rule in rules["groups"]: + transformed_rules["groups"].append(rule) + + rule_path.write_text(yaml.dump(transformed_rules)) + args = [str(self.path), "--format", "logql", "validate", str(rule_path)] + # noinspection PyBroadException + try: + self._exec(args) + return True, "" + except subprocess.CalledProcessError as e: + logger.debug("Validating the rules failed: %s", e.output) + return False, ", ".join([line for line in e.output if "error validating" in line]) + + def inject_label_matchers(self, expression, topology) -> str: + """Add label matchers to an expression.""" + if not topology: + return expression + if not self.path: + logger.debug("`cos-tool` unavailable. Leaving expression unchanged: %s", expression) + return expression + args = [str(self.path), "--format", "logql", "transform"] + args.extend( + ["--label-matcher={}={}".format(key, value) for key, value in topology.items()] + ) + + args.extend(["{}".format(expression)]) + # noinspection PyBroadException + try: + return self._exec(args) + except subprocess.CalledProcessError as e: + logger.debug('Applying the expression failed: "%s", falling back to the original', e) + print('Applying the expression failed: "{}", falling back to the original'.format(e)) + return expression + + def _get_tool_path(self) -> Optional[Path]: + arch = platform.processor() + arch = "amd64" if arch == "x86_64" else arch + res = "cos-tool-{}".format(arch) + try: + path = Path(res).resolve() + path.chmod(0o777) + return path + except NotImplementedError: + logger.debug("System lacks support for chmod") + except FileNotFoundError: + logger.debug('Could not locate cos-tool at: "{}"'.format(res)) + return None + + def _exec(self, cmd) -> str: + result = subprocess.run(cmd, check=True, stdout=subprocess.PIPE) + output = result.stdout.decode("utf-8").strip() + return output diff --git a/charms/jimm-k8s/lib/charms/nginx_ingress_integrator/v0/nginx_route.py b/charms/jimm-k8s/lib/charms/nginx_ingress_integrator/v0/nginx_route.py new file mode 100644 index 000000000..fd2f54d62 --- /dev/null +++ b/charms/jimm-k8s/lib/charms/nginx_ingress_integrator/v0/nginx_route.py @@ -0,0 +1,392 @@ +# Copyright 2023 Canonical Ltd. +# Licensed under the Apache2.0, see LICENCE file in charm source for details. +"""Library for the nginx-route relation. + +This library contains the require and provide functions for handling +the nginx-route interface. + +Import `require_nginx_route` in your charm, with four required keyword arguments: +- charm: (the charm itself) +- service_hostname +- service_name +- service_port + +Other optional arguments include: +- additional_hostnames +- backend_protocol +- limit_rps +- limit_whitelist +- max_body_size +- owasp_modsecurity_crs +- owasp_modsecurity_custom_rules +- path_routes +- retry_errors +- rewrite_target +- rewrite_enabled +- service_namespace +- session_cookie_max_age +- tls_secret_name + +See [the config section](https://charmhub.io/nginx-ingress-integrator/configure) for descriptions +of each, along with the required type. + +As an example, add the following to `src/charm.py`: +```python +from charms.nginx_ingress_integrator.v0.nginx_route import NginxRouteRequirer + +# In your charm's `__init__` method. +require_nginx_route( + charm=self, + service_hostname=self.config["external_hostname"], + service_name=self.app.name, + service_port=80 +) + +``` +And then add the following to `metadata.yaml`: +``` +requires: + nginx-route: + interface: nginx-route +``` +You _must_ require nginx route as part of the `__init__` method +rather than, for instance, a config-changed event handler, for the relation +changed event to be properly handled. +""" +import logging +import typing +import weakref + +import ops.charm +import ops.framework +import ops.model + +# The unique Charmhub library identifier, never change it +LIBID = "3c212b6ed3cf43dfbf9f2e322e634beb" + +# Increment this major API version when introducing breaking changes +LIBAPI = 0 + +# Increment this PATCH version before using `charmcraft publish-lib` or reset +# to 0 if you are raising the major API version +LIBPATCH = 2 + +__all__ = ["require_nginx_route", "provide_nginx_route"] + +logger = logging.getLogger(__name__) + + +class _NginxRouteAvailableEvent(ops.framework.EventBase): + """NginxRouteAvailableEvent custom event. + + This event indicates the nginx-route provider is available. + """ + + +class _NginxRouteBrokenEvent(ops.charm.RelationBrokenEvent): + """NginxRouteBrokenEvent custom event. + + This event indicates the nginx-route provider is broken. + """ + + +class _NginxRouteCharmEvents(ops.charm.CharmEvents): + """Custom charm events. + + Attrs: + nginx_route_available: Event to indicate that Nginx route relation is available. + nginx_route_broken: Event to indicate that Nginx route relation is broken. + """ + + nginx_route_available = ops.framework.EventSource(_NginxRouteAvailableEvent) + nginx_route_broken = ops.framework.EventSource(_NginxRouteBrokenEvent) + + +class _NginxRouteRequirer(ops.framework.Object): + """This class defines the functionality for the 'requires' side of the 'nginx-route' relation. + + Hook events observed: + - relation-changed + """ + + def __init__( + self, + charm: ops.charm.CharmBase, + config: typing.Dict[str, typing.Union[str, int, bool]], + nginx_route_relation_name: str = "nginx-route", + ): + """Init function for the NginxRouteRequires class. + + Args: + charm: The charm that requires the nginx-route relation. + config: Contains all the configuration options for nginx-route. + nginx_route_relation_name: Specifies the relation name of the relation handled by this + requirer class. The relation must have the nginx-route interface. + """ + super().__init__(charm, nginx_route_relation_name) + self._charm = charm + self._nginx_route_relation_name = nginx_route_relation_name + self._charm.framework.observe( + self._charm.on[self._nginx_route_relation_name].relation_changed, + self._config_reconciliation, + ) + # Set default values. + self._config: typing.Dict[str, typing.Union[str, int, bool]] = { + "service-namespace": self._charm.model.name, + **config, + } + self._config_reconciliation(None) + + def _config_reconciliation(self, _event: typing.Any = None) -> None: + """Update the nginx-route relation data to be exactly as defined by config.""" + if not self._charm.model.unit.is_leader(): + return + for relation in self._charm.model.relations[self._nginx_route_relation_name]: + relation_app_data = relation.data[self._charm.app] + delete_keys = { + relation_field + for relation_field in relation_app_data + if relation_field not in self._config + } + for delete_key in delete_keys: + del relation_app_data[delete_key] + relation_app_data.update({k: str(v) for k, v in self._config.items()}) + + +def require_nginx_route( # pylint: disable=too-many-locals,too-many-branches + *, + charm: ops.charm.CharmBase, + service_hostname: str, + service_name: str, + service_port: int, + additional_hostnames: typing.Optional[str] = None, + backend_protocol: typing.Optional[str] = None, + limit_rps: typing.Optional[int] = None, + limit_whitelist: typing.Optional[str] = None, + max_body_size: typing.Optional[int] = None, + owasp_modsecurity_crs: typing.Optional[str] = None, + owasp_modsecurity_custom_rules: typing.Optional[str] = None, + path_routes: typing.Optional[str] = None, + retry_errors: typing.Optional[str] = None, + rewrite_target: typing.Optional[str] = None, + rewrite_enabled: typing.Optional[bool] = None, + service_namespace: typing.Optional[str] = None, + session_cookie_max_age: typing.Optional[int] = None, + tls_secret_name: typing.Optional[str] = None, + nginx_route_relation_name: str = "nginx-route", +) -> None: + """Set up nginx-route relation handlers on the requirer side. + + This function must be invoked in the charm class constructor. + + Args: + charm: The charm that requires the nginx-route relation. + service_hostname: configure Nginx ingress integrator + service-hostname option via relation. + service_name: configure Nginx ingress integrator service-name + option via relation. + service_port: configure Nginx ingress integrator service-port + option via relation. + additional_hostnames: configure Nginx ingress integrator + additional-hostnames option via relation, optional. + backend_protocol: configure Nginx ingress integrator + backend-protocol option via relation, optional. + limit_rps: configure Nginx ingress integrator limit-rps + option via relation, optional. + limit_whitelist: configure Nginx ingress integrator + limit-whitelist option via relation, optional. + max_body_size: configure Nginx ingress integrator + max-body-size option via relation, optional. + owasp_modsecurity_crs: configure Nginx ingress integrator + owasp-modsecurity-crs option via relation, optional. + owasp_modsecurity_custom_rules: configure Nginx ingress + integrator owasp-modsecurity-custom-rules option via + relation, optional. + path_routes: configure Nginx ingress integrator path-routes + option via relation, optional. + retry_errors: configure Nginx ingress integrator retry-errors + option via relation, optional. + rewrite_target: configure Nginx ingress integrator + rewrite-target option via relation, optional. + rewrite_enabled: configure Nginx ingress integrator + rewrite-enabled option via relation, optional. + service_namespace: configure Nginx ingress integrator + service-namespace option via relation, optional. + session_cookie_max_age: configure Nginx ingress integrator + session-cookie-max-age option via relation, optional. + tls_secret_name: configure Nginx ingress integrator + tls-secret-name option via relation, optional. + nginx_route_relation_name: Specifies the relation name of + the relation handled by this requirer class. The relation + must have the nginx-route interface. + """ + config: typing.Dict[str, typing.Union[str, int, bool]] = {} + if service_hostname is not None: + config["service-hostname"] = service_hostname + if service_name is not None: + config["service-name"] = service_name + if service_port is not None: + config["service-port"] = service_port + if additional_hostnames is not None: + config["additional-hostnames"] = additional_hostnames + if backend_protocol is not None: + config["backend-protocol"] = backend_protocol + if limit_rps is not None: + config["limit-rps"] = limit_rps + if limit_whitelist is not None: + config["limit-whitelist"] = limit_whitelist + if max_body_size is not None: + config["max-body-size"] = max_body_size + if owasp_modsecurity_crs is not None: + config["owasp-modsecurity-crs"] = owasp_modsecurity_crs + if owasp_modsecurity_custom_rules is not None: + config["owasp-modsecurity-custom-rules"] = owasp_modsecurity_custom_rules + if path_routes is not None: + config["path-routes"] = path_routes + if retry_errors is not None: + config["retry-errors"] = retry_errors + if rewrite_target is not None: + config["rewrite-target"] = rewrite_target + if rewrite_enabled is not None: + config["rewrite-enabled"] = rewrite_enabled + if service_namespace is not None: + config["service-namespace"] = service_namespace + if session_cookie_max_age is not None: + config["session-cookie-max-age"] = session_cookie_max_age + if tls_secret_name is not None: + config["tls-secret-name"] = tls_secret_name + + _NginxRouteRequirer( + charm=charm, config=config, nginx_route_relation_name=nginx_route_relation_name + ) + + +class _NginxRouteProvider(ops.framework.Object): + """Class containing the functionality for the 'provides' side of the 'nginx-route' relation. + + Attrs: + on: nginx-route relation event describer. + + Hook events observed: + - relation-changed + """ + + on = _NginxRouteCharmEvents() + + def __init__( + self, + charm: ops.charm.CharmBase, + nginx_route_relation_name: str = "nginx-route", + ): + """Init function for the NginxRouterProvides class. + + Args: + charm: The charm that provides the nginx-route relation. + nginx_route_relation_name: Specifies the relation name of the relation handled by this + provider class. The relation must have the nginx-route interface. + """ + # Observe the relation-changed hook event and bind + # self.on_relation_changed() to handle the event. + super().__init__(charm, nginx_route_relation_name) + self._charm = charm + self._charm.framework.observe( + self._charm.on[nginx_route_relation_name].relation_changed, self._on_relation_changed + ) + self._charm.framework.observe( + self._charm.on[nginx_route_relation_name].relation_broken, self._on_relation_broken + ) + + def _on_relation_changed(self, event: ops.charm.RelationChangedEvent) -> None: + """Handle a change to the nginx-route relation. + + Confirm we have the fields we expect to receive. + + Args: + event: Event triggering the relation-changed hook for the relation. + """ + # `self.unit` isn't available here, so use `self.model.unit`. + if not self._charm.model.unit.is_leader(): + return + + relation_name = event.relation.name + remote_app = event.app + if remote_app is None: + raise RuntimeError("_on_relation_changed was triggered by a broken relation.") + + if not event.relation.data[remote_app]: + logger.info( + "%s hasn't finished configuring, waiting until the relation data is populated.", + relation_name, + ) + return + + required_fields = {"service-hostname", "service-port", "service-name"} + missing_fields = sorted( + field + for field in required_fields + if event.relation.data[remote_app].get(field) is None + ) + if missing_fields: + logger.warning( + "Missing required data fields for %s relation: %s", + relation_name, + ", ".join(missing_fields), + ) + self._charm.model.unit.status = ops.model.BlockedStatus( + f"Missing fields for {relation_name}: {', '.join(missing_fields)}" + ) + return + + # Create an event that our charm can use to decide it's okay to + # configure the Kubernetes Nginx ingress resources. + self.on.nginx_route_available.emit() + + def _on_relation_broken(self, event: ops.charm.RelationBrokenEvent) -> None: + """Handle a relation-broken event in the nginx-route relation. + + Args: + event: Event triggering the relation-broken hook for the relation. + """ + if not self._charm.model.unit.is_leader(): + return + + # Create an event that our charm can use to remove the Kubernetes Nginx ingress resources. + self.on.nginx_route_broken.emit(event.relation) + + +# This is here only to maintain a reference to the instance of NginxRouteProvider created by +# the provide_nginx_route function. This is required for ops framework event handling to work. +# The provider instance will have the same lifetime as the charm that creates it. +__provider_references: weakref.WeakKeyDictionary = weakref.WeakKeyDictionary() + + +def provide_nginx_route( + charm: ops.charm.CharmBase, + on_nginx_route_available: typing.Callable, + on_nginx_route_broken: typing.Callable, + nginx_route_relation_name: str = "nginx-route", +) -> None: + """Set up nginx-route relation handlers on the provider side. + + This function must be invoked in the charm class constructor. + + Args: + charm: The charm that requires the nginx-route relation. + on_nginx_route_available: Callback function for the nginx-route-available event. + on_nginx_route_broken: Callback function for the nginx-route-broken event. + nginx_route_relation_name: Specifies the relation name of the relation handled by this + provider class. The relation must have the nginx-route interface. + """ + if __provider_references.get(charm, {}).get(nginx_route_relation_name) is not None: + raise RuntimeError( + "provide_nginx_route was invoked twice with the same nginx-route relation name" + ) + provider = _NginxRouteProvider( + charm=charm, nginx_route_relation_name=nginx_route_relation_name + ) + if charm in __provider_references: + __provider_references[charm][nginx_route_relation_name] = provider + else: + __provider_references[charm] = {nginx_route_relation_name: provider} + charm.framework.observe(provider.on.nginx_route_available, on_nginx_route_available) + charm.framework.observe(provider.on.nginx_route_broken, on_nginx_route_broken) diff --git a/charms/jimm-k8s/lib/charms/observability_libs/v0/juju_topology.py b/charms/jimm-k8s/lib/charms/observability_libs/v0/juju_topology.py new file mode 100644 index 000000000..a79e5d434 --- /dev/null +++ b/charms/jimm-k8s/lib/charms/observability_libs/v0/juju_topology.py @@ -0,0 +1,301 @@ +# Copyright 2022 Canonical Ltd. +# See LICENSE file for licensing details. +"""## Overview. + +This document explains how to use the `JujuTopology` class to +create and consume topology information from Juju in a consistent manner. + +The goal of the Juju topology is to uniquely identify a piece +of software running across any of your Juju-managed deployments. +This is achieved by combining the following four elements: + +- Model name +- Model UUID +- Application name +- Unit identifier + + +For a more in-depth description of the concept, as well as a +walk-through of it's use-case in observability, see +[this blog post](https://juju.is/blog/model-driven-observability-part-2-juju-topology-metrics) +on the Juju blog. + +## Library Usage + +This library may be used to create and consume `JujuTopology` objects. +The `JujuTopology` class provides three ways to create instances: + +### Using the `from_charm` method + +Enables instantiation by supplying the charm as an argument. When +creating topology objects for the current charm, this is the recommended +approach. + +```python +topology = JujuTopology.from_charm(self) +``` + +### Using the `from_dict` method + +Allows for instantion using a dictionary of relation data, like the +`scrape_metadata` from Prometheus or the labels of an alert rule. When +creating topology objects for remote charms, this is the recommended +approach. + +```python +scrape_metadata = json.loads(relation.data[relation.app].get("scrape_metadata", "{}")) +topology = JujuTopology.from_dict(scrape_metadata) +``` + +### Using the class constructor + +Enables instantiation using whatever values you want. While this +is useful in some very specific cases, this is almost certainly not +what you are looking for as setting these values manually may +result in observability metrics which do not uniquely identify a +charm in order to provide accurate usage reporting, alerting, +horizontal scaling, or other use cases. + +```python +topology = JujuTopology( + model="some-juju-model", + model_uuid="00000000-0000-0000-0000-000000000001", + application="fancy-juju-application", + unit="fancy-juju-application/0", + charm_name="fancy-juju-application-k8s", +) +``` + +""" +from collections import OrderedDict +from typing import Dict, List, Optional +from uuid import UUID + +# The unique Charmhub library identifier, never change it +LIBID = "bced1658f20f49d28b88f61f83c2d232" + +LIBAPI = 0 +LIBPATCH = 6 + + +class InvalidUUIDError(Exception): + """Invalid UUID was provided.""" + + def __init__(self, uuid: str): + self.message = "'{}' is not a valid UUID.".format(uuid) + super().__init__(self.message) + + +class JujuTopology: + """JujuTopology is used for storing, generating and formatting juju topology information. + + DEPRECATED: This class is deprecated. Use `pip install cosl` and + `from cosl.juju_topology import JujuTopology` instead. + """ + + def __init__( + self, + model: str, + model_uuid: str, + application: str, + unit: Optional[str] = None, + charm_name: Optional[str] = None, + ): + """Build a JujuTopology object. + + A `JujuTopology` object is used for storing and transforming + Juju topology information. This information is used to + annotate Prometheus scrape jobs and alert rules. Such + annotation when applied to scrape jobs helps in identifying + the source of the scrapped metrics. On the other hand when + applied to alert rules topology information ensures that + evaluation of alert expressions is restricted to the source + (charm) from which the alert rules were obtained. + + Args: + model: a string name of the Juju model + model_uuid: a globally unique string identifier for the Juju model + application: an application name as a string + unit: a unit name as a string + charm_name: name of charm as a string + """ + if not self.is_valid_uuid(model_uuid): + raise InvalidUUIDError(model_uuid) + + self._model = model + self._model_uuid = model_uuid + self._application = application + self._charm_name = charm_name + self._unit = unit + + def is_valid_uuid(self, uuid): + """Validate the supplied UUID against the Juju Model UUID pattern. + + Args: + uuid: string that needs to be checked if it is valid v4 UUID. + + Returns: + True if parameter is a valid v4 UUID, False otherwise. + """ + try: + return str(UUID(uuid, version=4)) == uuid + except (ValueError, TypeError): + return False + + @classmethod + def from_charm(cls, charm): + """Creates a JujuTopology instance by using the model data available on a charm object. + + Args: + charm: a `CharmBase` object for which the `JujuTopology` will be constructed + Returns: + a `JujuTopology` object. + """ + return cls( + model=charm.model.name, + model_uuid=charm.model.uuid, + application=charm.model.app.name, + unit=charm.model.unit.name, + charm_name=charm.meta.name, + ) + + @classmethod + def from_dict(cls, data: dict): + """Factory method for creating `JujuTopology` children from a dictionary. + + Args: + data: a dictionary with five keys providing topology information. The keys are + - "model" + - "model_uuid" + - "application" + - "unit" + - "charm_name" + `unit` and `charm_name` may be empty, but will result in more limited + labels. However, this allows us to support charms without workloads. + + Returns: + a `JujuTopology` object. + """ + return cls( + model=data["model"], + model_uuid=data["model_uuid"], + application=data["application"], + unit=data.get("unit", ""), + charm_name=data.get("charm_name", ""), + ) + + def as_dict( + self, + *, + remapped_keys: Optional[Dict[str, str]] = None, + excluded_keys: Optional[List[str]] = None, + ) -> OrderedDict: + """Format the topology information into an ordered dict. + + Keeping the dictionary ordered is important to be able to + compare dicts without having to resort to deep comparisons. + + Args: + remapped_keys: A dictionary mapping old key names to new key names, + which will be substituted when invoked. + excluded_keys: A list of key names to exclude from the returned dict. + uuid_length: The length to crop the UUID to. + """ + ret = OrderedDict( + [ + ("model", self.model), + ("model_uuid", self.model_uuid), + ("application", self.application), + ("unit", self.unit), + ("charm_name", self.charm_name), + ] + ) + if excluded_keys: + ret = OrderedDict({k: v for k, v in ret.items() if k not in excluded_keys}) + + if remapped_keys: + ret = OrderedDict( + (remapped_keys.get(k), v) if remapped_keys.get(k) else (k, v) for k, v in ret.items() # type: ignore + ) + + return ret + + @property + def identifier(self) -> str: + """Format the topology information into a terse string. + + This crops the model UUID, making it unsuitable for comparisons against + anything but other identifiers. Mainly to be used as a display name or file + name where long strings might become an issue. + + >>> JujuTopology( \ + model = "a-model", \ + model_uuid = "00000000-0000-4000-8000-000000000000", \ + application = "some-app", \ + unit = "some-app/1" \ + ).identifier + 'a-model_00000000_some-app' + """ + parts = self.as_dict( + excluded_keys=["unit", "charm_name"], + ) + + parts["model_uuid"] = self.model_uuid_short + values = parts.values() + + return "_".join([str(val) for val in values]).replace("/", "_") + + @property + def label_matcher_dict(self) -> Dict[str, str]: + """Format the topology information into a dict with keys having 'juju_' as prefix. + + Relabelled topology never includes the unit as it would then only match + the leader unit (ie. the unit that produced the dict). + """ + items = self.as_dict( + remapped_keys={"charm_name": "charm"}, + excluded_keys=["unit"], + ).items() + + return {"juju_{}".format(key): value for key, value in items if value} + + @property + def label_matchers(self) -> str: + """Format the topology information into a promql/logql label matcher string. + + Topology label matchers should never include the unit as it + would then only match the leader unit (ie. the unit that + produced the matchers). + """ + items = self.label_matcher_dict.items() + return ", ".join(['{}="{}"'.format(key, value) for key, value in items if value]) + + @property + def model(self) -> str: + """Getter for the juju model value.""" + return self._model + + @property + def model_uuid(self) -> str: + """Getter for the juju model uuid value.""" + return self._model_uuid + + @property + def model_uuid_short(self) -> str: + """Getter for the juju model value, truncated to the first eight letters.""" + return self._model_uuid[:8] + + @property + def application(self) -> str: + """Getter for the juju application value.""" + return self._application + + @property + def charm_name(self) -> Optional[str]: + """Getter for the juju charm name value.""" + return self._charm_name + + @property + def unit(self) -> Optional[str]: + """Getter for the juju unit value.""" + return self._unit diff --git a/charms/jimm-k8s/lib/charms/prometheus_k8s/v0/prometheus_scrape.py b/charms/jimm-k8s/lib/charms/prometheus_k8s/v0/prometheus_scrape.py new file mode 100644 index 000000000..5e74edde0 --- /dev/null +++ b/charms/jimm-k8s/lib/charms/prometheus_k8s/v0/prometheus_scrape.py @@ -0,0 +1,2578 @@ +# Copyright 2021 Canonical Ltd. +# See LICENSE file for licensing details. +"""Prometheus Scrape Library. + +## Overview + +This document explains how to integrate with the Prometheus charm +for the purpose of providing a metrics endpoint to Prometheus. It +also explains how alternative implementations of the Prometheus charms +may maintain the same interface and be backward compatible with all +currently integrated charms. Finally this document is the +authoritative reference on the structure of relation data that is +shared between Prometheus charms and any other charm that intends to +provide a scrape target for Prometheus. + +## Source code + +Source code can be found on GitHub at: + https://github.com/canonical/prometheus-k8s-operator/tree/main/lib/charms/prometheus_k8s + +## Dependencies + +Using this library requires you to fetch the juju_topology library from +[observability-libs](https://charmhub.io/observability-libs/libraries/juju_topology). + +`charmcraft fetch-lib charms.observability_libs.v0.juju_topology` + +## Provider Library Usage + +This Prometheus charm interacts with its scrape targets using its +charm library. Charms seeking to expose metric endpoints for the +Prometheus charm, must do so using the `MetricsEndpointProvider` +object from this charm library. For the simplest use cases, using the +`MetricsEndpointProvider` object only requires instantiating it, +typically in the constructor of your charm (the one which exposes a +metrics endpoint). The `MetricsEndpointProvider` constructor requires +the name of the relation over which a scrape target (metrics endpoint) +is exposed to the Prometheus charm. This relation must use the +`prometheus_scrape` interface. By default address of the metrics +endpoint is set to the unit IP address, by each unit of the +`MetricsEndpointProvider` charm. These units set their address in +response to the `PebbleReady` event of each container in the unit, +since container restarts of Kubernetes charms can result in change of +IP addresses. The default name for the metrics endpoint relation is +`metrics-endpoint`. It is strongly recommended to use the same +relation name for consistency across charms and doing so obviates the +need for an additional constructor argument. The +`MetricsEndpointProvider` object may be instantiated as follows + + from charms.prometheus_k8s.v0.prometheus_scrape import MetricsEndpointProvider + + def __init__(self, *args): + super().__init__(*args) + ... + self.metrics_endpoint = MetricsEndpointProvider(self) + ... + +Note that the first argument (`self`) to `MetricsEndpointProvider` is +always a reference to the parent (scrape target) charm. + +An instantiated `MetricsEndpointProvider` object will ensure that each +unit of its parent charm, is a scrape target for the +`MetricsEndpointConsumer` (Prometheus) charm. By default +`MetricsEndpointProvider` assumes each unit of the consumer charm +exports its metrics at a path given by `/metrics` on port 80. These +defaults may be changed by providing the `MetricsEndpointProvider` +constructor an optional argument (`jobs`) that represents a +Prometheus scrape job specification using Python standard data +structures. This job specification is a subset of Prometheus' own +[scrape +configuration](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config) +format but represented using Python data structures. More than one job +may be provided using the `jobs` argument. Hence `jobs` accepts a list +of dictionaries where each dictionary represents one `` +object as described in the Prometheus documentation. The currently +supported configuration subset is: `job_name`, `metrics_path`, +`static_configs` + +Suppose it is required to change the port on which scraped metrics are +exposed to 8000. This may be done by providing the following data +structure as the value of `jobs`. + +``` +[ + { + "static_configs": [ + { + "targets": ["*:8000"] + } + ] + } +] +``` + +The wildcard ("*") host specification implies that the scrape targets +will automatically be set to the host addresses advertised by each +unit of the consumer charm. + +It is also possible to change the metrics path and scrape multiple +ports, for example + +``` +[ + { + "metrics_path": "/my-metrics-path", + "static_configs": [ + { + "targets": ["*:8000", "*:8081"], + } + ] + } +] +``` + +More complex scrape configurations are possible. For example + +``` +[ + { + "static_configs": [ + { + "targets": ["10.1.32.215:7000", "*:8000"], + "labels": { + "some_key": "some-value" + } + } + ] + } +] +``` + +This example scrapes the target "10.1.32.215" at port 7000 in addition +to scraping each unit at port 8000. There is however one difference +between wildcard targets (specified using "*") and fully qualified +targets (such as "10.1.32.215"). The Prometheus charm automatically +associates labels with metrics generated by each target. These labels +localise the source of metrics within the Juju topology by specifying +its "model name", "model UUID", "application name" and "unit +name". However unit name is associated only with wildcard targets but +not with fully qualified targets. + +Multiple jobs with different metrics paths and labels are allowed, but +each job must be given a unique name: + +``` +[ + { + "job_name": "my-first-job", + "metrics_path": "one-path", + "static_configs": [ + { + "targets": ["*:7000"], + "labels": { + "some_key": "some-value" + } + } + ] + }, + { + "job_name": "my-second-job", + "metrics_path": "another-path", + "static_configs": [ + { + "targets": ["*:8000"], + "labels": { + "some_other_key": "some-other-value" + } + } + ] + } +] +``` + +**Important:** `job_name` should be a fixed string (e.g. hardcoded literal). +For instance, if you include variable elements, like your `unit.name`, it may break +the continuity of the metrics time series gathered by Prometheus when the leader unit +changes (e.g. on upgrade or rescale). + +Additionally, it is also technically possible, but **strongly discouraged**, to +configure the following scrape-related settings, which behave as described by the +[Prometheus documentation](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config): + +- `static_configs` +- `scrape_interval` +- `scrape_timeout` +- `proxy_url` +- `relabel_configs` +- `metrics_relabel_configs` +- `sample_limit` +- `label_limit` +- `label_name_length_limit` +- `label_value_length_limit` + +The settings above are supported by the `prometheus_scrape` library only for the sake of +specialized facilities like the [Prometheus Scrape Config](https://charmhub.io/prometheus-scrape-config-k8s) +charm. Virtually no charms should use these settings, and charmers definitely **should not** +expose them to the Juju administrator via configuration options. + +## Consumer Library Usage + +The `MetricsEndpointConsumer` object may be used by Prometheus +charms to manage relations with their scrape targets. For this +purposes a Prometheus charm needs to do two things + +1. Instantiate the `MetricsEndpointConsumer` object by providing it a +reference to the parent (Prometheus) charm and optionally the name of +the relation that the Prometheus charm uses to interact with scrape +targets. This relation must confirm to the `prometheus_scrape` +interface and it is strongly recommended that this relation be named +`metrics-endpoint` which is its default value. + +For example a Prometheus charm may instantiate the +`MetricsEndpointConsumer` in its constructor as follows + + from charms.prometheus_k8s.v0.prometheus_scrape import MetricsEndpointConsumer + + def __init__(self, *args): + super().__init__(*args) + ... + self.metrics_consumer = MetricsEndpointConsumer(self) + ... + +2. A Prometheus charm also needs to respond to the +`TargetsChangedEvent` event of the `MetricsEndpointConsumer` by adding itself as +an observer for these events, as in + + self.framework.observe( + self.metrics_consumer.on.targets_changed, + self._on_scrape_targets_changed, + ) + +In responding to the `TargetsChangedEvent` event the Prometheus +charm must update the Prometheus configuration so that any new scrape +targets are added and/or old ones removed from the list of scraped +endpoints. For this purpose the `MetricsEndpointConsumer` object +exposes a `jobs()` method that returns a list of scrape jobs. Each +element of this list is the Prometheus scrape configuration for that +job. In order to update the Prometheus configuration, the Prometheus +charm needs to replace the current list of jobs with the list provided +by `jobs()` as follows + + def _on_scrape_targets_changed(self, event): + ... + scrape_jobs = self.metrics_consumer.jobs() + for job in scrape_jobs: + prometheus_scrape_config.append(job) + ... + +## Alerting Rules + +This charm library also supports gathering alerting rules from all +related `MetricsEndpointProvider` charms and enabling corresponding alerts within the +Prometheus charm. Alert rules are automatically gathered by `MetricsEndpointProvider` +charms when using this library, from a directory conventionally named +`prometheus_alert_rules`. This directory must reside at the top level +in the `src` folder of the consumer charm. Each file in this directory +is assumed to be in one of two formats: +- the official prometheus alert rule format, conforming to the +[Prometheus docs](https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/) +- a single rule format, which is a simplified subset of the official format, +comprising a single alert rule per file, using the same YAML fields. + +The file name must have one of the following extensions: +- `.rule` +- `.rules` +- `.yml` +- `.yaml` + +An example of the contents of such a file in the custom single rule +format is shown below. + +``` +alert: HighRequestLatency +expr: job:request_latency_seconds:mean5m{my_key=my_value} > 0.5 +for: 10m +labels: + severity: Medium + type: HighLatency +annotations: + summary: High request latency for {{ $labels.instance }}. +``` + +The `MetricsEndpointProvider` will read all available alert rules and +also inject "filtering labels" into the alert expressions. The +filtering labels ensure that alert rules are localised to the metrics +provider charm's Juju topology (application, model and its UUID). Such +a topology filter is essential to ensure that alert rules submitted by +one provider charm generates alerts only for that same charm. When +alert rules are embedded in a charm, and the charm is deployed as a +Juju application, the alert rules from that application have their +expressions automatically updated to filter for metrics coming from +the units of that application alone. This remove risk of spurious +evaluation, e.g., when you have multiple deployments of the same charm +monitored by the same Prometheus. + +Not all alerts one may want to specify can be embedded in a +charm. Some alert rules will be specific to a user's use case. This is +the case, for example, of alert rules that are based on business +constraints, like expecting a certain amount of requests to a specific +API every five minutes. Such alert rules can be specified via the +[COS Config Charm](https://charmhub.io/cos-configuration-k8s), +which allows importing alert rules and other settings like dashboards +from a Git repository. + +Gathering alert rules and generating rule files within the Prometheus +charm is easily done using the `alerts()` method of +`MetricsEndpointConsumer`. Alerts generated by Prometheus will +automatically include Juju topology labels in the alerts. These labels +indicate the source of the alert. The following labels are +automatically included with each alert + +- `juju_model` +- `juju_model_uuid` +- `juju_application` + +## Relation Data + +The Prometheus charm uses both application and unit relation data to +obtain information regarding its scrape jobs, alert rules and scrape +targets. This relation data is in JSON format and it closely resembles +the YAML structure of Prometheus [scrape configuration] +(https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config). + +Units of Metrics provider charms advertise their names and addresses +over unit relation data using the `prometheus_scrape_unit_name` and +`prometheus_scrape_unit_address` keys. While the `scrape_metadata`, +`scrape_jobs` and `alert_rules` keys in application relation data +of Metrics provider charms hold eponymous information. + +""" # noqa: W505 + +import copy +import hashlib +import ipaddress +import json +import logging +import os +import platform +import re +import socket +import subprocess +import tempfile +from collections import defaultdict +from pathlib import Path +from typing import Any, Callable, Dict, List, Optional, Tuple, Union +from urllib.error import HTTPError, URLError +from urllib.parse import urlparse +from urllib.request import urlopen + +import yaml +from charms.observability_libs.v0.juju_topology import JujuTopology +from ops.charm import CharmBase, RelationRole +from ops.framework import ( + BoundEvent, + EventBase, + EventSource, + Object, + ObjectEvents, + StoredDict, + StoredList, + StoredState, +) +from ops.model import Relation + +# The unique Charmhub library identifier, never change it +LIBID = "bc84295fef5f4049878f07b131968ee2" + +# Increment this major API version when introducing breaking changes +LIBAPI = 0 + +# Increment this PATCH version before using `charmcraft publish-lib` or reset +# to 0 if you are raising the major API version +LIBPATCH = 36 + +logger = logging.getLogger(__name__) + + +ALLOWED_KEYS = { + "job_name", + "metrics_path", + "static_configs", + "scrape_interval", + "scrape_timeout", + "proxy_url", + "relabel_configs", + "metrics_relabel_configs", + "sample_limit", + "label_limit", + "label_name_length_limit", + "label_value_length_limit", + "scheme", + "basic_auth", + "tls_config", +} +DEFAULT_JOB = { + "metrics_path": "/metrics", + "static_configs": [{"targets": ["*:80"]}], +} + + +DEFAULT_RELATION_NAME = "metrics-endpoint" +RELATION_INTERFACE_NAME = "prometheus_scrape" + +DEFAULT_ALERT_RULES_RELATIVE_PATH = "./src/prometheus_alert_rules" + + +class PrometheusConfig: + """A namespace for utility functions for manipulating the prometheus config dict.""" + + # relabel instance labels so that instance identifiers are globally unique + # stable over unit recreation + topology_relabel_config = { + "source_labels": ["juju_model", "juju_model_uuid", "juju_application"], + "separator": "_", + "target_label": "instance", + "regex": "(.*)", + } + + topology_relabel_config_wildcard = { + "source_labels": ["juju_model", "juju_model_uuid", "juju_application", "juju_unit"], + "separator": "_", + "target_label": "instance", + "regex": "(.*)", + } + + @staticmethod + def sanitize_scrape_config(job: dict) -> dict: + """Restrict permissible scrape configuration options. + + If job is empty then a default job is returned. The + default job is + + ``` + { + "metrics_path": "/metrics", + "static_configs": [{"targets": ["*:80"]}], + } + ``` + + Args: + job: a dict containing a single Prometheus job + specification. + + Returns: + a dictionary containing a sanitized job specification. + """ + sanitized_job = DEFAULT_JOB.copy() + sanitized_job.update({key: value for key, value in job.items() if key in ALLOWED_KEYS}) + return sanitized_job + + @staticmethod + def sanitize_scrape_configs(scrape_configs: List[dict]) -> List[dict]: + """A vectorized version of `sanitize_scrape_config`.""" + return [PrometheusConfig.sanitize_scrape_config(job) for job in scrape_configs] + + @staticmethod + def prefix_job_names(scrape_configs: List[dict], prefix: str) -> List[dict]: + """Adds the given prefix to all the job names in the given scrape_configs list.""" + modified_scrape_configs = [] + for scrape_config in scrape_configs: + job_name = scrape_config.get("job_name") + modified = scrape_config.copy() + modified["job_name"] = prefix + "_" + job_name if job_name else prefix + modified_scrape_configs.append(modified) + + return modified_scrape_configs + + @staticmethod + def expand_wildcard_targets_into_individual_jobs( + scrape_jobs: List[dict], + hosts: Dict[str, Tuple[str, str]], + topology: Optional[JujuTopology] = None, + ) -> List[dict]: + """Extract wildcard hosts from the given scrape_configs list into separate jobs. + + Args: + scrape_jobs: list of scrape jobs. + hosts: a dictionary mapping host names to host address for + all units of the relation for which this job configuration + must be constructed. + topology: optional arg for adding topology labels to scrape targets. + """ + # hosts = self._relation_hosts(relation) + + modified_scrape_jobs = [] + for job in scrape_jobs: + static_configs = job.get("static_configs") + if not static_configs: + continue + + # When a single unit specified more than one wildcard target, then they are expanded + # into a static_config per target + non_wildcard_static_configs = [] + + for static_config in static_configs: + targets = static_config.get("targets") + if not targets: + continue + + # All non-wildcard targets remain in the same static_config + non_wildcard_targets = [] + + # All wildcard targets are extracted to a job per unit. If multiple wildcard + # targets are specified, they remain in the same static_config (per unit). + wildcard_targets = [] + + for target in targets: + match = re.compile(r"\*(?:(:\d+))?").match(target) + if match: + # This is a wildcard target. + # Need to expand into separate jobs and remove it from this job here + wildcard_targets.append(target) + else: + # This is not a wildcard target. Copy it over into its own static_config. + non_wildcard_targets.append(target) + + # All non-wildcard targets remain in the same static_config + if non_wildcard_targets: + non_wildcard_static_config = static_config.copy() + non_wildcard_static_config["targets"] = non_wildcard_targets + + if topology: + # When non-wildcard targets (aka fully qualified hostnames) are specified, + # there is no reliable way to determine the name (Juju topology unit name) + # for such a target. Therefore labeling with Juju topology, excluding the + # unit name. + non_wildcard_static_config["labels"] = { + **non_wildcard_static_config.get("labels", {}), + **topology.label_matcher_dict, + } + + non_wildcard_static_configs.append(non_wildcard_static_config) + + # Extract wildcard targets into individual jobs + if wildcard_targets: + for unit_name, (unit_hostname, unit_path) in hosts.items(): + modified_job = job.copy() + modified_job["static_configs"] = [static_config.copy()] + modified_static_config = modified_job["static_configs"][0] + modified_static_config["targets"] = [ + target.replace("*", unit_hostname) for target in wildcard_targets + ] + + unit_num = unit_name.split("/")[-1] + job_name = modified_job.get("job_name", "unnamed-job") + "-" + unit_num + modified_job["job_name"] = job_name + modified_job["metrics_path"] = unit_path + ( + job.get("metrics_path") or "/metrics" + ) + + if topology: + # Add topology labels + modified_static_config["labels"] = { + **modified_static_config.get("labels", {}), + **topology.label_matcher_dict, + **{"juju_unit": unit_name}, + } + + # Instance relabeling for topology should be last in order. + modified_job["relabel_configs"] = modified_job.get( + "relabel_configs", [] + ) + [PrometheusConfig.topology_relabel_config_wildcard] + + modified_scrape_jobs.append(modified_job) + + if non_wildcard_static_configs: + modified_job = job.copy() + modified_job["static_configs"] = non_wildcard_static_configs + modified_job["metrics_path"] = modified_job.get("metrics_path") or "/metrics" + + if topology: + # Instance relabeling for topology should be last in order. + modified_job["relabel_configs"] = modified_job.get("relabel_configs", []) + [ + PrometheusConfig.topology_relabel_config + ] + + modified_scrape_jobs.append(modified_job) + + return modified_scrape_jobs + + @staticmethod + def render_alertmanager_static_configs(alertmanagers: List[str]): + """Render the alertmanager static_configs section from a list of URLs. + + Each target must be in the hostname:port format, and prefixes are specified in a separate + key. Therefore, with ingress in place, would need to extract the path into the + `path_prefix` key, which is higher up in the config hierarchy. + + https://prometheus.io/docs/prometheus/latest/configuration/configuration/#alertmanager_config + + Args: + alertmanagers: List of alertmanager URLs. + + Returns: + A dict representation for the static_configs section. + """ + # Make sure it's a valid url so urlparse could parse it. + scheme = re.compile(r"^https?://") + sanitized = [am if scheme.search(am) else "http://" + am for am in alertmanagers] + + # Create a mapping from paths to netlocs + # Group alertmanager targets into a dictionary of lists: + # {path: [netloc1, netloc2]} + paths = defaultdict(list) # type: Dict[str, List[str]] + for parsed in map(urlparse, sanitized): + path = parsed.path or "/" + paths[path].append(parsed.netloc) + + return { + "alertmanagers": [ + {"path_prefix": path_prefix, "static_configs": [{"targets": netlocs}]} + for path_prefix, netlocs in paths.items() + ] + } + + +class RelationNotFoundError(Exception): + """Raised if there is no relation with the given name is found.""" + + def __init__(self, relation_name: str): + self.relation_name = relation_name + self.message = "No relation named '{}' found".format(relation_name) + + super().__init__(self.message) + + +class RelationInterfaceMismatchError(Exception): + """Raised if the relation with the given name has a different interface.""" + + def __init__( + self, + relation_name: str, + expected_relation_interface: str, + actual_relation_interface: str, + ): + self.relation_name = relation_name + self.expected_relation_interface = expected_relation_interface + self.actual_relation_interface = actual_relation_interface + self.message = ( + "The '{}' relation has '{}' as interface rather than the expected '{}'".format( + relation_name, actual_relation_interface, expected_relation_interface + ) + ) + + super().__init__(self.message) + + +class RelationRoleMismatchError(Exception): + """Raised if the relation with the given name has a different role.""" + + def __init__( + self, + relation_name: str, + expected_relation_role: RelationRole, + actual_relation_role: RelationRole, + ): + self.relation_name = relation_name + self.expected_relation_interface = expected_relation_role + self.actual_relation_role = actual_relation_role + self.message = "The '{}' relation has role '{}' rather than the expected '{}'".format( + relation_name, repr(actual_relation_role), repr(expected_relation_role) + ) + + super().__init__(self.message) + + +class InvalidAlertRuleEvent(EventBase): + """Event emitted when alert rule files are not parsable. + + Enables us to set a clear status on the provider. + """ + + def __init__(self, handle, errors: str = "", valid: bool = False): + super().__init__(handle) + self.errors = errors + self.valid = valid + + def snapshot(self) -> Dict: + """Save alert rule information.""" + return { + "valid": self.valid, + "errors": self.errors, + } + + def restore(self, snapshot): + """Restore alert rule information.""" + self.valid = snapshot["valid"] + self.errors = snapshot["errors"] + + +class InvalidScrapeJobEvent(EventBase): + """Event emitted when alert rule files are not valid.""" + + def __init__(self, handle, errors: str = ""): + super().__init__(handle) + self.errors = errors + + def snapshot(self) -> Dict: + """Save error information.""" + return {"errors": self.errors} + + def restore(self, snapshot): + """Restore error information.""" + self.errors = snapshot["errors"] + + +class MetricsEndpointProviderEvents(ObjectEvents): + """Events raised by :class:`InvalidAlertRuleEvent`s.""" + + alert_rule_status_changed = EventSource(InvalidAlertRuleEvent) + invalid_scrape_job = EventSource(InvalidScrapeJobEvent) + + +def _type_convert_stored(obj): + """Convert Stored* to their appropriate types, recursively.""" + if isinstance(obj, StoredList): + return list(map(_type_convert_stored, obj)) + if isinstance(obj, StoredDict): + rdict = {} # type: Dict[Any, Any] + for k in obj.keys(): + rdict[k] = _type_convert_stored(obj[k]) + return rdict + return obj + + +def _validate_relation_by_interface_and_direction( + charm: CharmBase, + relation_name: str, + expected_relation_interface: str, + expected_relation_role: RelationRole, +): + """Verifies that a relation has the necessary characteristics. + + Verifies that the `relation_name` provided: (1) exists in metadata.yaml, + (2) declares as interface the interface name passed as `relation_interface` + and (3) has the right "direction", i.e., it is a relation that `charm` + provides or requires. + + Args: + charm: a `CharmBase` object to scan for the matching relation. + relation_name: the name of the relation to be verified. + expected_relation_interface: the interface name to be matched by the + relation named `relation_name`. + expected_relation_role: whether the `relation_name` must be either + provided or required by `charm`. + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the same relation interface + as specified via the `expected_relation_interface` argument. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the same role as specified + via the `expected_relation_role` argument. + """ + if relation_name not in charm.meta.relations: + raise RelationNotFoundError(relation_name) + + relation = charm.meta.relations[relation_name] + + actual_relation_interface = relation.interface_name + if actual_relation_interface != expected_relation_interface: + raise RelationInterfaceMismatchError( + relation_name, expected_relation_interface, actual_relation_interface + ) + + if expected_relation_role == RelationRole.provides: + if relation_name not in charm.meta.provides: + raise RelationRoleMismatchError( + relation_name, RelationRole.provides, RelationRole.requires + ) + elif expected_relation_role == RelationRole.requires: + if relation_name not in charm.meta.requires: + raise RelationRoleMismatchError( + relation_name, RelationRole.requires, RelationRole.provides + ) + else: + raise Exception("Unexpected RelationDirection: {}".format(expected_relation_role)) + + +class InvalidAlertRulePathError(Exception): + """Raised if the alert rules folder cannot be found or is otherwise invalid.""" + + def __init__( + self, + alert_rules_absolute_path: Path, + message: str, + ): + self.alert_rules_absolute_path = alert_rules_absolute_path + self.message = message + + super().__init__(self.message) + + +def _is_official_alert_rule_format(rules_dict: dict) -> bool: + """Are alert rules in the upstream format as supported by Prometheus. + + Alert rules in dictionary format are in "official" form if they + contain a "groups" key, since this implies they contain a list of + alert rule groups. + + Args: + rules_dict: a set of alert rules in Python dictionary format + + Returns: + True if alert rules are in official Prometheus file format. + """ + return "groups" in rules_dict + + +def _is_single_alert_rule_format(rules_dict: dict) -> bool: + """Are alert rules in single rule format. + + The Prometheus charm library supports reading of alert rules in a + custom format that consists of a single alert rule per file. This + does not conform to the official Prometheus alert rule file format + which requires that each alert rules file consists of a list of + alert rule groups and each group consists of a list of alert + rules. + + Alert rules in dictionary form are considered to be in single rule + format if in the least it contains two keys corresponding to the + alert rule name and alert expression. + + Returns: + True if alert rule is in single rule file format. + """ + # one alert rule per file + return set(rules_dict) >= {"alert", "expr"} + + +class AlertRules: + """Utility class for amalgamating prometheus alert rule files and injecting juju topology. + + An `AlertRules` object supports aggregating alert rules from files and directories in both + official and single rule file formats using the `add_path()` method. All the alert rules + read are annotated with Juju topology labels and amalgamated into a single data structure + in the form of a Python dictionary using the `as_dict()` method. Such a dictionary can be + easily dumped into JSON format and exchanged over relation data. The dictionary can also + be dumped into YAML format and written directly into an alert rules file that is read by + Prometheus. Note that multiple `AlertRules` objects must not be written into the same file, + since Prometheus allows only a single list of alert rule groups per alert rules file. + + The official Prometheus format is a YAML file conforming to the Prometheus documentation + (https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/). + The custom single rule format is a subsection of the official YAML, having a single alert + rule, effectively "one alert per file". + """ + + # This class uses the following terminology for the various parts of a rule file: + # - alert rules file: the entire groups[] yaml, including the "groups:" key. + # - alert groups (plural): the list of groups[] (a list, i.e. no "groups:" key) - it is a list + # of dictionaries that have the "name" and "rules" keys. + # - alert group (singular): a single dictionary that has the "name" and "rules" keys. + # - alert rules (plural): all the alerts in a given alert group - a list of dictionaries with + # the "alert" and "expr" keys. + # - alert rule (singular): a single dictionary that has the "alert" and "expr" keys. + + def __init__(self, topology: Optional[JujuTopology] = None): + """Build and alert rule object. + + Args: + topology: an optional `JujuTopology` instance that is used to annotate all alert rules. + """ + self.topology = topology + self.tool = CosTool(None) + self.alert_groups = [] # type: List[dict] + + def _from_file(self, root_path: Path, file_path: Path) -> List[dict]: + """Read a rules file from path, injecting juju topology. + + Args: + root_path: full path to the root rules folder (used only for generating group name) + file_path: full path to a *.rule file. + + Returns: + A list of dictionaries representing the rules file, if file is valid (the structure is + formed by `yaml.safe_load` of the file); an empty list otherwise. + """ + with file_path.open() as rf: + # Load a list of rules from file then add labels and filters + try: + rule_file = yaml.safe_load(rf) + + except Exception as e: + logger.error("Failed to read alert rules from %s: %s", file_path.name, e) + return [] + + if not rule_file: + logger.warning("Empty rules file: %s", file_path.name) + return [] + if not isinstance(rule_file, dict): + logger.error("Invalid rules file (must be a dict): %s", file_path.name) + return [] + if _is_official_alert_rule_format(rule_file): + alert_groups = rule_file["groups"] + elif _is_single_alert_rule_format(rule_file): + # convert to list of alert groups + # group name is made up from the file name + alert_groups = [{"name": file_path.stem, "rules": [rule_file]}] + else: + # invalid/unsupported + logger.error("Invalid rules file: %s", file_path.name) + return [] + + # update rules with additional metadata + for alert_group in alert_groups: + # update group name with topology and sub-path + alert_group["name"] = self._group_name( + str(root_path), + str(file_path), + alert_group["name"], + ) + + # add "juju_" topology labels + for alert_rule in alert_group["rules"]: + if "labels" not in alert_rule: + alert_rule["labels"] = {} + + if self.topology: + alert_rule["labels"].update(self.topology.label_matcher_dict) + # insert juju topology filters into a prometheus alert rule + alert_rule["expr"] = self.tool.inject_label_matchers( + re.sub(r"%%juju_topology%%,?", "", alert_rule["expr"]), + self.topology.label_matcher_dict, + ) + + return alert_groups + + def _group_name(self, root_path: str, file_path: str, group_name: str) -> str: + """Generate group name from path and topology. + + The group name is made up of the relative path between the root dir_path, the file path, + and topology identifier. + + Args: + root_path: path to the root rules dir. + file_path: path to rule file. + group_name: original group name to keep as part of the new augmented group name + + Returns: + New group name, augmented by juju topology and relative path. + """ + rel_path = os.path.relpath(os.path.dirname(file_path), root_path) + rel_path = "" if rel_path == "." else rel_path.replace(os.path.sep, "_") + + # Generate group name: + # - name, from juju topology + # - suffix, from the relative path of the rule file; + group_name_parts = [self.topology.identifier] if self.topology else [] + group_name_parts.extend([rel_path, group_name, "alerts"]) + # filter to remove empty strings + return "_".join(filter(None, group_name_parts)) + + @classmethod + def _multi_suffix_glob( + cls, dir_path: Path, suffixes: List[str], recursive: bool = True + ) -> list: + """Helper function for getting all files in a directory that have a matching suffix. + + Args: + dir_path: path to the directory to glob from. + suffixes: list of suffixes to include in the glob (items should begin with a period). + recursive: a flag indicating whether a glob is recursive (nested) or not. + + Returns: + List of files in `dir_path` that have one of the suffixes specified in `suffixes`. + """ + all_files_in_dir = dir_path.glob("**/*" if recursive else "*") + return list(filter(lambda f: f.is_file() and f.suffix in suffixes, all_files_in_dir)) + + def _from_dir(self, dir_path: Path, recursive: bool) -> List[dict]: + """Read all rule files in a directory. + + All rules from files for the same directory are loaded into a single + group. The generated name of this group includes juju topology. + By default, only the top directory is scanned; for nested scanning, pass `recursive=True`. + + Args: + dir_path: directory containing *.rule files (alert rules without groups). + recursive: flag indicating whether to scan for rule files recursively. + + Returns: + a list of dictionaries representing prometheus alert rule groups, each dictionary + representing an alert group (structure determined by `yaml.safe_load`). + """ + alert_groups = [] # type: List[dict] + + # Gather all alerts into a list of groups + for file_path in self._multi_suffix_glob( + dir_path, [".rule", ".rules", ".yml", ".yaml"], recursive + ): + alert_groups_from_file = self._from_file(dir_path, file_path) + if alert_groups_from_file: + logger.debug("Reading alert rule from %s", file_path) + alert_groups.extend(alert_groups_from_file) + + return alert_groups + + def add_path(self, path: str, *, recursive: bool = False) -> None: + """Add rules from a dir path. + + All rules from files are aggregated into a data structure representing a single rule file. + All group names are augmented with juju topology. + + Args: + path: either a rules file or a dir of rules files. + recursive: whether to read files recursively or not (no impact if `path` is a file). + + Returns: + True if path was added else False. + """ + path = Path(path) # type: Path + if path.is_dir(): + self.alert_groups.extend(self._from_dir(path, recursive)) + elif path.is_file(): + self.alert_groups.extend(self._from_file(path.parent, path)) + else: + logger.debug("Alert rules path does not exist: %s", path) + + def as_dict(self) -> dict: + """Return standard alert rules file in dict representation. + + Returns: + a dictionary containing a single list of alert rule groups. + The list of alert rule groups is provided as value of the + "groups" dictionary key. + """ + return {"groups": self.alert_groups} if self.alert_groups else {} + + +class TargetsChangedEvent(EventBase): + """Event emitted when Prometheus scrape targets change.""" + + def __init__(self, handle, relation_id): + super().__init__(handle) + self.relation_id = relation_id + + def snapshot(self): + """Save scrape target relation information.""" + return {"relation_id": self.relation_id} + + def restore(self, snapshot): + """Restore scrape target relation information.""" + self.relation_id = snapshot["relation_id"] + + +class MonitoringEvents(ObjectEvents): + """Event descriptor for events raised by `MetricsEndpointConsumer`.""" + + targets_changed = EventSource(TargetsChangedEvent) + + +class MetricsEndpointConsumer(Object): + """A Prometheus based Monitoring service.""" + + on = MonitoringEvents() + + def __init__(self, charm: CharmBase, relation_name: str = DEFAULT_RELATION_NAME): + """A Prometheus based Monitoring service. + + Args: + charm: a `CharmBase` instance that manages this + instance of the Prometheus service. + relation_name: an optional string name of the relation between `charm` + and the Prometheus charmed service. The default is "metrics-endpoint". + It is strongly advised not to change the default, so that people + deploying your charm will have a consistent experience with all + other charms that consume metrics endpoints. + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the `prometheus_scrape` relation + interface. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the `RelationRole.requires` + role. + """ + _validate_relation_by_interface_and_direction( + charm, relation_name, RELATION_INTERFACE_NAME, RelationRole.requires + ) + + super().__init__(charm, relation_name) + self._charm = charm + self._relation_name = relation_name + self._tool = CosTool(self._charm) + events = self._charm.on[relation_name] + self.framework.observe(events.relation_changed, self._on_metrics_provider_relation_changed) + self.framework.observe( + events.relation_departed, self._on_metrics_provider_relation_departed + ) + + def _on_metrics_provider_relation_changed(self, event): + """Handle changes with related metrics providers. + + Anytime there are changes in relations between Prometheus + and metrics provider charms the Prometheus charm is informed, + through a `TargetsChangedEvent` event. The Prometheus charm can + then choose to update its scrape configuration. + + Args: + event: a `CharmEvent` in response to which the Prometheus + charm must update its scrape configuration. + """ + rel_id = event.relation.id + + self.on.targets_changed.emit(relation_id=rel_id) + + def _on_metrics_provider_relation_departed(self, event): + """Update job config when a metrics provider departs. + + When a metrics provider departs the Prometheus charm is informed + through a `TargetsChangedEvent` event so that it can update its + scrape configuration to ensure that the departed metrics provider + is removed from the list of scrape jobs and + + Args: + event: a `CharmEvent` that indicates a metrics provider + unit has departed. + """ + rel_id = event.relation.id + self.on.targets_changed.emit(relation_id=rel_id) + + def jobs(self) -> list: + """Fetch the list of scrape jobs. + + Returns: + A list consisting of all the static scrape configurations + for each related `MetricsEndpointProvider` that has specified + its scrape targets. + """ + scrape_jobs = [] + + for relation in self._charm.model.relations[self._relation_name]: + static_scrape_jobs = self._static_scrape_config(relation) + if static_scrape_jobs: + # Duplicate job names will cause validate_scrape_jobs to fail. + # Therefore we need to dedupe here and after all jobs are collected. + static_scrape_jobs = _dedupe_job_names(static_scrape_jobs) + try: + self._tool.validate_scrape_jobs(static_scrape_jobs) + except subprocess.CalledProcessError as e: + if self._charm.unit.is_leader(): + data = json.loads(relation.data[self._charm.app].get("event", "{}")) + data["scrape_job_errors"] = str(e) + relation.data[self._charm.app]["event"] = json.dumps(data) + else: + scrape_jobs.extend(static_scrape_jobs) + + scrape_jobs = _dedupe_job_names(scrape_jobs) + + return scrape_jobs + + @property + def alerts(self) -> dict: + """Fetch alerts for all relations. + + A Prometheus alert rules file consists of a list of "groups". Each + group consists of a list of alerts (`rules`) that are sequentially + executed. This method returns all the alert rules provided by each + related metrics provider charm. These rules may be used to generate a + separate alert rules file for each relation since the returned list + of alert groups are indexed by that relations Juju topology identifier. + The Juju topology identifier string includes substrings that identify + alert rule related metadata such as the Juju model, model UUID and the + application name from where the alert rule originates. Since this + topology identifier is globally unique, it may be used for instance as + the name for the file into which the list of alert rule groups are + written. For each relation, the structure of data returned is a dictionary + representation of a standard prometheus rules file: + + {"groups": [{"name": ...}, ...]} + + per official prometheus documentation + https://prometheus.io/docs/prometheus/latest/configuration/alerting_rules/ + + The value of the `groups` key is such that it may be used to generate + a Prometheus alert rules file directly using `yaml.dump` but the + `groups` key itself must be included as this is required by Prometheus. + + For example the list of alert rule groups returned by this method may + be written into files consumed by Prometheus as follows + + ``` + for topology_identifier, alert_rule_groups in self.metrics_consumer.alerts().items(): + filename = "juju_" + topology_identifier + ".rules" + path = os.path.join(PROMETHEUS_RULES_DIR, filename) + rules = yaml.safe_dump(alert_rule_groups) + container.push(path, rules, make_dirs=True) + ``` + + Returns: + A dictionary mapping the Juju topology identifier of the source charm to + its list of alert rule groups. + """ + alerts = {} # type: Dict[str, dict] # mapping b/w juju identifiers and alert rule files + for relation in self._charm.model.relations[self._relation_name]: + if not relation.units or not relation.app: + continue + + alert_rules = json.loads(relation.data[relation.app].get("alert_rules", "{}")) + if not alert_rules: + continue + + alert_rules = self._inject_alert_expr_labels(alert_rules) + + identifier, topology = self._get_identifier_by_alert_rules(alert_rules) + if not topology: + try: + scrape_metadata = json.loads(relation.data[relation.app]["scrape_metadata"]) + identifier = JujuTopology.from_dict(scrape_metadata).identifier + alerts[identifier] = self._tool.apply_label_matchers(alert_rules) # type: ignore + + except KeyError as e: + logger.debug( + "Relation %s has no 'scrape_metadata': %s", + relation.id, + e, + ) + + if not identifier: + logger.error( + "Alert rules were found but no usable group or identifier was present." + ) + continue + + alerts[identifier] = alert_rules + + _, errmsg = self._tool.validate_alert_rules(alert_rules) + if errmsg: + if alerts[identifier]: + del alerts[identifier] + if self._charm.unit.is_leader(): + data = json.loads(relation.data[self._charm.app].get("event", "{}")) + data["errors"] = errmsg + relation.data[self._charm.app]["event"] = json.dumps(data) + continue + + return alerts + + def _get_identifier_by_alert_rules( + self, rules: dict + ) -> Tuple[Union[str, None], Union[JujuTopology, None]]: + """Determine an appropriate dict key for alert rules. + + The key is used as the filename when writing alerts to disk, so the structure + and uniqueness is important. + + Args: + rules: a dict of alert rules + Returns: + A tuple containing an identifier, if found, and a JujuTopology, if it could + be constructed. + """ + if "groups" not in rules: + logger.debug("No alert groups were found in relation data") + return None, None + + # Construct an ID based on what's in the alert rules if they have labels + for group in rules["groups"]: + try: + labels = group["rules"][0]["labels"] + topology = JujuTopology( + # Don't try to safely get required constructor fields. There's already + # a handler for KeyErrors + model_uuid=labels["juju_model_uuid"], + model=labels["juju_model"], + application=labels["juju_application"], + unit=labels.get("juju_unit", ""), + charm_name=labels.get("juju_charm", ""), + ) + return topology.identifier, topology + except KeyError: + logger.debug("Alert rules were found but no usable labels were present") + continue + + logger.warning( + "No labeled alert rules were found, and no 'scrape_metadata' " + "was available. Using the alert group name as filename." + ) + try: + for group in rules["groups"]: + return group["name"], None + except KeyError: + logger.debug("No group name was found to use as identifier") + + return None, None + + def _inject_alert_expr_labels(self, rules: Dict[str, Any]) -> Dict[str, Any]: + """Iterate through alert rules and inject topology into expressions. + + Args: + rules: a dict of alert rules + """ + if "groups" not in rules: + return rules + + modified_groups = [] + for group in rules["groups"]: + # Copy off rules, so we don't modify an object we're iterating over + rules_copy = group["rules"] + for idx, rule in enumerate(rules_copy): + labels = rule.get("labels") + + if labels: + try: + topology = JujuTopology( + # Don't try to safely get required constructor fields. There's already + # a handler for KeyErrors + model_uuid=labels["juju_model_uuid"], + model=labels["juju_model"], + application=labels["juju_application"], + unit=labels.get("juju_unit", ""), + charm_name=labels.get("juju_charm", ""), + ) + + # Inject topology and put it back in the list + rule["expr"] = self._tool.inject_label_matchers( + re.sub(r"%%juju_topology%%,?", "", rule["expr"]), + topology.label_matcher_dict, + ) + except KeyError: + # Some required JujuTopology key is missing. Just move on. + pass + + group["rules"][idx] = rule + + modified_groups.append(group) + + rules["groups"] = modified_groups + return rules + + def _static_scrape_config(self, relation) -> list: + """Generate the static scrape configuration for a single relation. + + If the relation data includes `scrape_metadata` then the value + of this key is used to annotate the scrape jobs with Juju + Topology labels before returning them. + + Args: + relation: an `ops.model.Relation` object whose static + scrape configuration is required. + + Returns: + A list (possibly empty) of scrape jobs. Each job is a + valid Prometheus scrape configuration for that job, + represented as a Python dictionary. + """ + if not relation.units: + return [] + + scrape_jobs = json.loads(relation.data[relation.app].get("scrape_jobs", "[]")) + + if not scrape_jobs: + return [] + + scrape_metadata = json.loads(relation.data[relation.app].get("scrape_metadata", "{}")) + + if not scrape_metadata: + return scrape_jobs + + topology = JujuTopology.from_dict(scrape_metadata) + + job_name_prefix = "juju_{}_prometheus_scrape".format(topology.identifier) + scrape_jobs = PrometheusConfig.prefix_job_names(scrape_jobs, job_name_prefix) + scrape_jobs = PrometheusConfig.sanitize_scrape_configs(scrape_jobs) + + hosts = self._relation_hosts(relation) + + scrape_jobs = PrometheusConfig.expand_wildcard_targets_into_individual_jobs( + scrape_jobs, hosts, topology + ) + + return scrape_jobs + + def _relation_hosts(self, relation: Relation) -> Dict[str, Tuple[str, str]]: + """Returns a mapping from unit names to (address, path) tuples, for the given relation.""" + hosts = {} + for unit in relation.units: + # TODO deprecate and remove unit.name + unit_name = relation.data[unit].get("prometheus_scrape_unit_name") or unit.name + # TODO deprecate and remove "prometheus_scrape_host" + unit_address = relation.data[unit].get( + "prometheus_scrape_unit_address" + ) or relation.data[unit].get("prometheus_scrape_host") + unit_path = relation.data[unit].get("prometheus_scrape_unit_path", "") + if unit_name and unit_address: + hosts.update({unit_name: (unit_address, unit_path)}) + + return hosts + + def _target_parts(self, target) -> list: + """Extract host and port from a wildcard target. + + Args: + target: a string specifying a scrape target. A + scrape target is expected to have the format + "host:port". The host part may be a wildcard + "*" and the port part can be missing (along + with ":") in which case port is set to 80. + + Returns: + a list with target host and port as in [host, port] + """ + if ":" in target: + parts = target.split(":") + else: + parts = [target, "80"] + + return parts + + +def _dedupe_job_names(jobs: List[dict]): + """Deduplicate a list of dicts by appending a hash to the value of the 'job_name' key. + + Additionally, fully de-duplicate any identical jobs. + + Args: + jobs: A list of prometheus scrape jobs + """ + jobs_copy = copy.deepcopy(jobs) + + # Convert to a dict with job names as keys + # I think this line is O(n^2) but it should be okay given the list sizes + jobs_dict = { + job["job_name"]: list(filter(lambda x: x["job_name"] == job["job_name"], jobs_copy)) + for job in jobs_copy + } + + # If multiple jobs have the same name, convert the name to "name_" + for key in jobs_dict: + if len(jobs_dict[key]) > 1: + for job in jobs_dict[key]: + job_json = json.dumps(job) + hashed = hashlib.sha256(job_json.encode()).hexdigest() + job["job_name"] = "{}_{}".format(job["job_name"], hashed) + new_jobs = [] + for key in jobs_dict: + new_jobs.extend(list(jobs_dict[key])) + + # Deduplicate jobs which are equal + # Again this in O(n^2) but it should be okay + deduped_jobs = [] + seen = [] + for job in new_jobs: + job_json = json.dumps(job) + hashed = hashlib.sha256(job_json.encode()).hexdigest() + if hashed in seen: + continue + seen.append(hashed) + deduped_jobs.append(job) + + return deduped_jobs + + +def _resolve_dir_against_charm_path(charm: CharmBase, *path_elements: str) -> str: + """Resolve the provided path items against the directory of the main file. + + Look up the directory of the `main.py` file being executed. This is normally + going to be the charm.py file of the charm including this library. Then, resolve + the provided path elements and, if the result path exists and is a directory, + return its absolute path; otherwise, raise en exception. + + Raises: + InvalidAlertRulePathError, if the path does not exist or is not a directory. + """ + charm_dir = Path(str(charm.charm_dir)) + if not charm_dir.exists() or not charm_dir.is_dir(): + # Operator Framework does not currently expose a robust + # way to determine the top level charm source directory + # that is consistent across deployed charms and unit tests + # Hence for unit tests the current working directory is used + # TODO: updated this logic when the following ticket is resolved + # https://github.com/canonical/operator/issues/643 + charm_dir = Path(os.getcwd()) + + alerts_dir_path = charm_dir.absolute().joinpath(*path_elements) + + if not alerts_dir_path.exists(): + raise InvalidAlertRulePathError(alerts_dir_path, "directory does not exist") + if not alerts_dir_path.is_dir(): + raise InvalidAlertRulePathError(alerts_dir_path, "is not a directory") + + return str(alerts_dir_path) + + +class MetricsEndpointProvider(Object): + """A metrics endpoint for Prometheus.""" + + on = MetricsEndpointProviderEvents() + + def __init__( + self, + charm, + relation_name: str = DEFAULT_RELATION_NAME, + jobs=None, + alert_rules_path: str = DEFAULT_ALERT_RULES_RELATIVE_PATH, + refresh_event: Optional[Union[BoundEvent, List[BoundEvent]]] = None, + external_url: str = "", + lookaside_jobs_callable: Optional[Callable] = None, + ): + """Construct a metrics provider for a Prometheus charm. + + If your charm exposes a Prometheus metrics endpoint, the + `MetricsEndpointProvider` object enables your charm to easily + communicate how to reach that metrics endpoint. + + By default, a charm instantiating this object has the metrics + endpoints of each of its units scraped by the related Prometheus + charms. The scraped metrics are automatically tagged by the + Prometheus charms with Juju topology data via the + `juju_model_name`, `juju_model_uuid`, `juju_application_name` + and `juju_unit` labels. To support such tagging `MetricsEndpointProvider` + automatically forwards scrape metadata to a `MetricsEndpointConsumer` + (Prometheus charm). + + Scrape targets provided by `MetricsEndpointProvider` can be + customized when instantiating this object. For example in the + case of a charm exposing the metrics endpoint for each of its + units on port 8080 and the `/metrics` path, the + `MetricsEndpointProvider` can be instantiated as follows: + + self.metrics_endpoint_provider = MetricsEndpointProvider( + self, + jobs=[{ + "static_configs": [{"targets": ["*:8080"]}], + }]) + + The notation `*:` means "scrape each unit of this charm on port + ``. + + In case the metrics endpoints are not on the standard `/metrics` path, + a custom path can be specified as follows: + + self.metrics_endpoint_provider = MetricsEndpointProvider( + self, + jobs=[{ + "metrics_path": "/my/strange/metrics/path", + "static_configs": [{"targets": ["*:8080"]}], + }]) + + Note how the `jobs` argument is a list: this allows you to expose multiple + combinations of paths "metrics_path" and "static_configs" in case your charm + exposes multiple endpoints, which could happen, for example, when you have + multiple workload containers, with applications in each needing to be scraped. + The structure of the objects in the `jobs` list is one-to-one with the + `scrape_config` configuration item of Prometheus' own configuration (see + https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config + ), but with only a subset of the fields allowed. The permitted fields are + listed in `ALLOWED_KEYS` object in this charm library module. + + It is also possible to specify alert rules. By default, this library will look + into the `/prometheus_alert_rules`, which in a standard charm + layouts resolves to `src/prometheus_alert_rules`. Each alert rule goes into a + separate `*.rule` file. If the syntax of a rule is invalid, + the `MetricsEndpointProvider` logs an error and does not load the particular + rule. + + To avoid false positives and negatives in the evaluation of alert rules, + all ingested alert rule expressions are automatically qualified using Juju + Topology filters. This ensures that alert rules provided by your charm, trigger + alerts based only on data scrapped from your charm. For example an alert rule + such as the following + + alert: UnitUnavailable + expr: up < 1 + for: 0m + + will be automatically transformed into something along the lines of the following + + alert: UnitUnavailable + expr: up{juju_model=, juju_model_uuid=, juju_application=} < 1 + for: 0m + + An attempt will be made to validate alert rules prior to loading them into Prometheus. + If they are invalid, an event will be emitted from this object which charms can respond + to in order to set a meaningful status for administrators. + + This can be observed via `consumer.on.alert_rule_status_changed` which contains: + - The error(s) encountered when validating as `errors` + - A `valid` attribute, which can be used to reset the state of charms if alert rules + are updated via another mechanism (e.g. `cos-config`) and refreshed. + + Args: + charm: a `CharmBase` object that manages this + `MetricsEndpointProvider` object. Typically, this is + `self` in the instantiating class. + relation_name: an optional string name of the relation between `charm` + and the Prometheus charmed service. The default is "metrics-endpoint". + It is strongly advised not to change the default, so that people + deploying your charm will have a consistent experience with all + other charms that provide metrics endpoints. + jobs: an optional list of dictionaries where each + dictionary represents the Prometheus scrape + configuration for a single job. When not provided, a + default scrape configuration is provided for the + `/metrics` endpoint polling all units of the charm on port `80` + using the `MetricsEndpointProvider` object. + alert_rules_path: an optional path for the location of alert rules + files. Defaults to "./prometheus_alert_rules", + resolved relative to the directory hosting the charm entry file. + The alert rules are automatically updated on charm upgrade. + refresh_event: an optional bound event or list of bound events which + will be observed to re-set scrape job data (IP address and others) + external_url: an optional argument that represents an external url that + can be generated by an Ingress or a Proxy. + lookaside_jobs_callable: an optional `Callable` which should be invoked + when the job configuration is built as a secondary mapping. The callable + should return a `List[Dict]` which is syntactically identical to the + `jobs` parameter, but can be updated out of step initialization of + this library without disrupting the 'global' job spec. + + Raises: + RelationNotFoundError: If there is no relation in the charm's metadata.yaml + with the same name as provided via `relation_name` argument. + RelationInterfaceMismatchError: The relation with the same name as provided + via `relation_name` argument does not have the `prometheus_scrape` relation + interface. + RelationRoleMismatchError: If the relation with the same name as provided + via `relation_name` argument does not have the `RelationRole.provides` + role. + """ + _validate_relation_by_interface_and_direction( + charm, relation_name, RELATION_INTERFACE_NAME, RelationRole.provides + ) + + try: + alert_rules_path = _resolve_dir_against_charm_path(charm, alert_rules_path) + except InvalidAlertRulePathError as e: + logger.debug( + "Invalid Prometheus alert rules folder at %s: %s", + e.alert_rules_absolute_path, + e.message, + ) + + super().__init__(charm, relation_name) + self.topology = JujuTopology.from_charm(charm) + + self._charm = charm + self._alert_rules_path = alert_rules_path + self._relation_name = relation_name + # sanitize job configurations to the supported subset of parameters + jobs = [] if jobs is None else jobs + self._jobs = PrometheusConfig.sanitize_scrape_configs(jobs) + + if external_url: + external_url = ( + external_url if urlparse(external_url).scheme else ("http://" + external_url) + ) + self.external_url = external_url + self._lookaside_jobs = lookaside_jobs_callable + + events = self._charm.on[self._relation_name] + self.framework.observe(events.relation_changed, self._on_relation_changed) + + if not refresh_event: + # FIXME remove once podspec charms are verified. + # `self.set_scrape_job_spec()` is called every re-init so this should not be needed. + if len(self._charm.meta.containers) == 1: + if "kubernetes" in self._charm.meta.series: + # This is a podspec charm + refresh_event = [self._charm.on.update_status] + else: + # This is a sidecar/pebble charm + container = list(self._charm.meta.containers.values())[0] + refresh_event = [self._charm.on[container.name.replace("-", "_")].pebble_ready] + else: + logger.warning( + "%d containers are present in metadata.yaml and " + "refresh_event was not specified. Defaulting to update_status. " + "Metrics IP may not be set in a timely fashion.", + len(self._charm.meta.containers), + ) + refresh_event = [self._charm.on.update_status] + + else: + if not isinstance(refresh_event, list): + refresh_event = [refresh_event] + + self.framework.observe(events.relation_joined, self.set_scrape_job_spec) + for ev in refresh_event: + self.framework.observe(ev, self.set_scrape_job_spec) + + def _on_relation_changed(self, event): + """Check for alert rule messages in the relation data before moving on.""" + if self._charm.unit.is_leader(): + ev = json.loads(event.relation.data[event.app].get("event", "{}")) + + if ev: + valid = bool(ev.get("valid", True)) + errors = ev.get("errors", "") + + if valid and not errors: + self.on.alert_rule_status_changed.emit(valid=valid) + else: + self.on.alert_rule_status_changed.emit(valid=valid, errors=errors) + + scrape_errors = ev.get("scrape_job_errors", None) + if scrape_errors: + self.on.invalid_scrape_job.emit(errors=scrape_errors) + + def update_scrape_job_spec(self, jobs): + """Update scrape job specification.""" + self._jobs = PrometheusConfig.sanitize_scrape_configs(jobs) + self.set_scrape_job_spec() + + def set_scrape_job_spec(self, _=None): + """Ensure scrape target information is made available to prometheus. + + When a metrics provider charm is related to a prometheus charm, the + metrics provider sets specification and metadata related to its own + scrape configuration. This information is set using Juju application + data. In addition, each of the consumer units also sets its own + host address in Juju unit relation data. + """ + self._set_unit_ip() + + if not self._charm.unit.is_leader(): + return + + alert_rules = AlertRules(topology=self.topology) + alert_rules.add_path(self._alert_rules_path, recursive=True) + alert_rules_as_dict = alert_rules.as_dict() + + for relation in self._charm.model.relations[self._relation_name]: + relation.data[self._charm.app]["scrape_metadata"] = json.dumps(self._scrape_metadata) + relation.data[self._charm.app]["scrape_jobs"] = json.dumps(self._scrape_jobs) + + if alert_rules_as_dict: + # Update relation data with the string representation of the rule file. + # Juju topology is already included in the "scrape_metadata" field above. + # The consumer side of the relation uses this information to name the rules file + # that is written to the filesystem. + relation.data[self._charm.app]["alert_rules"] = json.dumps(alert_rules_as_dict) + + def _set_unit_ip(self, _=None): + """Set unit host address. + + Each time a metrics provider charm container is restarted it updates its own + host address in the unit relation data for the prometheus charm. + + The only argument specified is an event, and it ignored. This is for expediency + to be able to use this method as an event handler, although no access to the + event is actually needed. + """ + for relation in self._charm.model.relations[self._relation_name]: + unit_ip = str(self._charm.model.get_binding(relation).network.bind_address) + + # TODO store entire url in relation data, instead of only select url parts. + + if self.external_url: + parsed = urlparse(self.external_url) + unit_address = parsed.hostname + path = parsed.path + elif self._is_valid_unit_address(unit_ip): + unit_address = unit_ip + path = "" + else: + unit_address = socket.getfqdn() + path = "" + + relation.data[self._charm.unit]["prometheus_scrape_unit_address"] = unit_address + relation.data[self._charm.unit]["prometheus_scrape_unit_path"] = path + relation.data[self._charm.unit]["prometheus_scrape_unit_name"] = str( + self._charm.model.unit.name + ) + + def _is_valid_unit_address(self, address: str) -> bool: + """Validate a unit address. + + At present only IP address validation is supported, but + this may be extended to DNS addresses also, as needed. + + Args: + address: a string representing a unit address + """ + try: + _ = ipaddress.ip_address(address) + except ValueError: + return False + + return True + + @property + def _scrape_jobs(self) -> list: + """Fetch list of scrape jobs. + + Returns: + A list of dictionaries, where each dictionary specifies a + single scrape job for Prometheus. + """ + jobs = self._jobs if self._jobs else [DEFAULT_JOB] + if callable(self._lookaside_jobs): + return jobs + PrometheusConfig.sanitize_scrape_configs(self._lookaside_jobs()) + return jobs + + @property + def _scrape_metadata(self) -> dict: + """Generate scrape metadata. + + Returns: + Scrape configuration metadata for this metrics provider charm. + """ + return self.topology.as_dict() + + +class PrometheusRulesProvider(Object): + """Forward rules to Prometheus. + + This object may be used to forward rules to Prometheus. At present it only supports + forwarding alert rules. This is unlike :class:`MetricsEndpointProvider`, which + is used for forwarding both scrape targets and associated alert rules. This object + is typically used when there is a desire to forward rules that apply globally (across + all deployed charms and units) rather than to a single charm. All rule files are + forwarded using the same 'prometheus_scrape' interface that is also used by + `MetricsEndpointProvider`. + + Args: + charm: A charm instance that `provides` a relation with the `prometheus_scrape` interface. + relation_name: Name of the relation in `metadata.yaml` that + has the `prometheus_scrape` interface. + dir_path: Root directory for the collection of rule files. + recursive: Whether to scan for rule files recursively. + """ + + def __init__( + self, + charm: CharmBase, + relation_name: str = DEFAULT_RELATION_NAME, + dir_path: str = DEFAULT_ALERT_RULES_RELATIVE_PATH, + recursive=True, + ): + super().__init__(charm, relation_name) + self._charm = charm + self._relation_name = relation_name + self._recursive = recursive + + try: + dir_path = _resolve_dir_against_charm_path(charm, dir_path) + except InvalidAlertRulePathError as e: + logger.debug( + "Invalid Prometheus alert rules folder at %s: %s", + e.alert_rules_absolute_path, + e.message, + ) + self.dir_path = dir_path + + events = self._charm.on[self._relation_name] + event_sources = [ + events.relation_joined, + events.relation_changed, + self._charm.on.leader_elected, + self._charm.on.upgrade_charm, + ] + + for event_source in event_sources: + self.framework.observe(event_source, self._update_relation_data) + + def _reinitialize_alert_rules(self): + """Reloads alert rules and updates all relations.""" + self._update_relation_data(None) + + def _update_relation_data(self, _): + """Update application relation data with alert rules for all relations.""" + if not self._charm.unit.is_leader(): + return + + alert_rules = AlertRules() + alert_rules.add_path(self.dir_path, recursive=self._recursive) + alert_rules_as_dict = alert_rules.as_dict() + + logger.info("Updating relation data with rule files from disk") + for relation in self._charm.model.relations[self._relation_name]: + relation.data[self._charm.app]["alert_rules"] = json.dumps( + alert_rules_as_dict, + sort_keys=True, # sort, to prevent unnecessary relation_changed events + ) + + +class MetricsEndpointAggregator(Object): + """Aggregate metrics from multiple scrape targets. + + `MetricsEndpointAggregator` collects scrape target information from one + or more related charms and forwards this to a `MetricsEndpointConsumer` + charm, which may be in a different Juju model. However, it is + essential that `MetricsEndpointAggregator` itself resides in the same + model as its scrape targets, as this is currently the only way to + ensure in Juju that the `MetricsEndpointAggregator` will be able to + determine the model name and uuid of the scrape targets. + + `MetricsEndpointAggregator` should be used in place of + `MetricsEndpointProvider` in the following two use cases: + + 1. Integrating one or more scrape targets that do not support the + `prometheus_scrape` interface. + + 2. Integrating one or more scrape targets through cross model + relations. Although the [Scrape Config Operator](https://charmhub.io/cos-configuration-k8s) + may also be used for the purpose of supporting cross model + relations. + + Using `MetricsEndpointAggregator` to build a Prometheus charm client + only requires instantiating it. Instantiating + `MetricsEndpointAggregator` is similar to `MetricsEndpointProvider` except + that it requires specifying the names of three relations: the + relation with scrape targets, the relation for alert rules, and + that with the Prometheus charms. For example + + ```python + self._aggregator = MetricsEndpointAggregator( + self, + { + "prometheus": "monitoring", + "scrape_target": "prometheus-target", + "alert_rules": "prometheus-rules" + } + ) + ``` + + `MetricsEndpointAggregator` assumes that each unit of a scrape target + sets in its unit-level relation data two entries with keys + "hostname" and "port". If it is required to integrate with charms + that do not honor these assumptions, it is always possible to + derive from `MetricsEndpointAggregator` overriding the `_get_targets()` + method, which is responsible for aggregating the unit name, host + address ("hostname") and port of the scrape target. + `MetricsEndpointAggregator` also assumes that each unit of a + scrape target sets in its unit-level relation data a key named + "groups". The value of this key is expected to be the string + representation of list of Prometheus Alert rules in YAML format. + An example of a single such alert rule is + + ```yaml + - alert: HighRequestLatency + expr: job:request_latency_seconds:mean5m{job="myjob"} > 0.5 + for: 10m + labels: + severity: page + annotations: + summary: High request latency + ``` + + Once again if it is required to integrate with charms that do not + honour these assumptions about alert rules then an object derived + from `MetricsEndpointAggregator` may be used by overriding the + `_get_alert_rules()` method. + + `MetricsEndpointAggregator` ensures that Prometheus scrape job + specifications and alert rules are annotated with Juju topology + information, just like `MetricsEndpointProvider` and + `MetricsEndpointConsumer` do. + + By default, `MetricsEndpointAggregator` ensures that Prometheus + "instance" labels refer to Juju topology. This ensures that + instance labels are stable over unit recreation. While it is not + advisable to change this option, if required it can be done by + setting the "relabel_instance" keyword argument to `False` when + constructing an aggregator object. + """ + + _stored = StoredState() + + def __init__( + self, + charm, + relation_names: Optional[dict] = None, + relabel_instance=True, + resolve_addresses=False, + ): + """Construct a `MetricsEndpointAggregator`. + + Args: + charm: a `CharmBase` object that manages this + `MetricsEndpointAggregator` object. Typically, this is + `self` in the instantiating class. + relation_names: a dictionary with three keys. The value + of the "scrape_target" and "alert_rules" keys are + the relation names over which scrape job and alert rule + information is gathered by this `MetricsEndpointAggregator`. + And the value of the "prometheus" key is the name of + the relation with a `MetricsEndpointConsumer` such as + the Prometheus charm. + relabel_instance: A boolean flag indicating if Prometheus + scrape job "instance" labels must refer to Juju Topology. + resolve_addresses: A boolean flag indiccating if the aggregator + should attempt to perform DNS lookups of targets and append + a `dns_name` label + """ + self._charm = charm + + relation_names = relation_names or {} + + self._prometheus_relation = relation_names.get( + "prometheus", "downstream-prometheus-scrape" + ) + self._target_relation = relation_names.get("scrape_target", "prometheus-target") + self._alert_rules_relation = relation_names.get("alert_rules", "prometheus-rules") + + super().__init__(charm, self._prometheus_relation) + self._stored.set_default(jobs=[], alert_rules=[]) + + self._relabel_instance = relabel_instance + self._resolve_addresses = resolve_addresses + + # manage Prometheus charm relation events + prometheus_events = self._charm.on[self._prometheus_relation] + self.framework.observe(prometheus_events.relation_joined, self._set_prometheus_data) + + # manage list of Prometheus scrape jobs from related scrape targets + target_events = self._charm.on[self._target_relation] + self.framework.observe(target_events.relation_changed, self._on_prometheus_targets_changed) + self.framework.observe( + target_events.relation_departed, self._on_prometheus_targets_departed + ) + + # manage alert rules for Prometheus from related scrape targets + alert_rule_events = self._charm.on[self._alert_rules_relation] + self.framework.observe(alert_rule_events.relation_changed, self._on_alert_rules_changed) + self.framework.observe(alert_rule_events.relation_departed, self._on_alert_rules_departed) + + def _set_prometheus_data(self, event): + """Ensure every new Prometheus instances is updated. + + Any time a new Prometheus unit joins the relation with + `MetricsEndpointAggregator`, that Prometheus unit is provided + with the complete set of existing scrape jobs and alert rules. + """ + if not self._charm.unit.is_leader(): + return + + jobs = [] + _type_convert_stored( + self._stored.jobs + ) # list of scrape jobs, one per relation + for relation in self.model.relations[self._target_relation]: + targets = self._get_targets(relation) + if targets and relation.app: + jobs.append(self._static_scrape_job(targets, relation.app.name)) + + groups = [] + _type_convert_stored(self._stored.alert_rules) # list of alert rule groups + for relation in self.model.relations[self._alert_rules_relation]: + unit_rules = self._get_alert_rules(relation) + if unit_rules and relation.app: + appname = relation.app.name + rules = self._label_alert_rules(unit_rules, appname) + group = {"name": self.group_name(appname), "rules": rules} + groups.append(group) + + event.relation.data[self._charm.app]["scrape_jobs"] = json.dumps(jobs) + event.relation.data[self._charm.app]["alert_rules"] = json.dumps({"groups": groups}) + + def _on_prometheus_targets_changed(self, event): + """Update scrape jobs in response to scrape target changes. + + When there is any change in relation data with any scrape + target, the Prometheus scrape job, for that specific target is + updated. + """ + targets = self._get_targets(event.relation) + if not targets: + return + + # new scrape job for the relation that has changed + self.set_target_job_data(targets, event.relation.app.name) + + def set_target_job_data(self, targets: dict, app_name: str, **kwargs) -> None: + """Update scrape jobs in response to scrape target changes. + + When there is any change in relation data with any scrape + target, the Prometheus scrape job, for that specific target is + updated. Additionally, if this method is called manually, do the + same. + + Args: + targets: a `dict` containing target information + app_name: a `str` identifying the application + kwargs: a `dict` of the extra arguments passed to the function + """ + if not self._charm.unit.is_leader(): + return + + # new scrape job for the relation that has changed + updated_job = self._static_scrape_job(targets, app_name, **kwargs) + + for relation in self.model.relations[self._prometheus_relation]: + jobs = json.loads(relation.data[self._charm.app].get("scrape_jobs", "[]")) + # list of scrape jobs that have not changed + jobs = [job for job in jobs if updated_job["job_name"] != job["job_name"]] + jobs.append(updated_job) + relation.data[self._charm.app]["scrape_jobs"] = json.dumps(jobs) + + if not _type_convert_stored(self._stored.jobs) == jobs: + self._stored.jobs = jobs + + def _on_prometheus_targets_departed(self, event): + """Remove scrape jobs when a target departs. + + Any time a scrape target departs, any Prometheus scrape job + associated with that specific scrape target is removed. + """ + job_name = self._job_name(event.relation.app.name) + unit_name = event.unit.name + self.remove_prometheus_jobs(job_name, unit_name) + + def remove_prometheus_jobs(self, job_name: str, unit_name: Optional[str] = ""): + """Given a job name and unit name, remove scrape jobs associated. + + The `unit_name` parameter is used for automatic, relation data bag-based + generation, where the unit name in labels can be used to ensure that jobs with + similar names (which are generated via the app name when scanning relation data + bags) are not accidentally removed, as their unit name labels will differ. + For NRPE, the job name is calculated from an ID sent via the NRPE relation, and is + sufficient to uniquely identify the target. + """ + if not self._charm.unit.is_leader(): + return + + for relation in self.model.relations[self._prometheus_relation]: + jobs = json.loads(relation.data[self._charm.app].get("scrape_jobs", "[]")) + if not jobs: + continue + + changed_job = [j for j in jobs if j.get("job_name") == job_name] + if not changed_job: + continue + changed_job = changed_job[0] + + # list of scrape jobs that have not changed + jobs = [job for job in jobs if job.get("job_name") != job_name] + + # list of scrape jobs for units of the same application that still exist + configs_kept = [ + config + for config in changed_job["static_configs"] # type: ignore + if config.get("labels", {}).get("juju_unit") != unit_name + ] + + if configs_kept: + changed_job["static_configs"] = configs_kept # type: ignore + jobs.append(changed_job) + + relation.data[self._charm.app]["scrape_jobs"] = json.dumps(jobs) + + if not _type_convert_stored(self._stored.jobs) == jobs: + self._stored.jobs = jobs + + def _job_name(self, appname) -> str: + """Construct a scrape job name. + + Each relation has its own unique scrape job name. All units in + the relation are scraped as part of the same scrape job. + + Args: + appname: string name of a related application. + + Returns: + a string Prometheus scrape job name for the application. + """ + return "juju_{}_{}_{}_prometheus_scrape".format( + self.model.name, self.model.uuid[:7], appname + ) + + def _get_targets(self, relation) -> dict: + """Fetch scrape targets for a relation. + + Scrape target information is returned for each unit in the + relation. This information contains the unit name, network + hostname (or address) for that unit, and port on which a + metrics endpoint is exposed in that unit. + + Args: + relation: an `ops.model.Relation` object for which scrape + targets are required. + + Returns: + a dictionary whose keys are names of the units in the + relation. There values associated with each key is itself + a dictionary of the form + ``` + {"hostname": hostname, "port": port} + ``` + """ + targets = {} + for unit in relation.units: + port = relation.data[unit].get("port", 80) + hostname = relation.data[unit].get("hostname") + if hostname: + targets.update({unit.name: {"hostname": hostname, "port": port}}) + + return targets + + def _static_scrape_job(self, targets, application_name, **kwargs) -> dict: + """Construct a static scrape job for an application. + + Args: + targets: a dictionary providing hostname and port for all + scrape target. The keys of this dictionary are unit + names. Values corresponding to these keys are + themselves a dictionary with keys "hostname" and + "port". + application_name: a string name of the application for + which this static scrape job is being constructed. + kwargs: a `dict` of the extra arguments passed to the function + + Returns: + A dictionary corresponding to a Prometheus static scrape + job configuration for one application. The returned + dictionary may be transformed into YAML and appended to + the list of any existing list of Prometheus static configs. + """ + juju_model = self.model.name + juju_model_uuid = self.model.uuid + + job = { + "job_name": self._job_name(application_name), + "static_configs": [ + { + "targets": ["{}:{}".format(target["hostname"], target["port"])], + "labels": { + "juju_model": juju_model, + "juju_model_uuid": juju_model_uuid, + "juju_application": application_name, + "juju_unit": unit_name, + "host": target["hostname"], + # Expanding this will merge the dicts and replace the + # topology labels if any were present/found + **self._static_config_extra_labels(target), + }, + } + for unit_name, target in targets.items() + ], + "relabel_configs": self._relabel_configs + kwargs.get("relabel_configs", []), + } + job.update(kwargs.get("updates", {})) + + return job + + def _static_config_extra_labels(self, target: Dict[str, str]) -> Dict[str, str]: + """Build a list of extra static config parameters, if specified.""" + extra_info = {} + + if self._resolve_addresses: + try: + dns_name = socket.gethostbyaddr(target["hostname"])[0] + except OSError: + logger.debug("Could not perform DNS lookup for %s", target["hostname"]) + dns_name = target["hostname"] + extra_info["dns_name"] = dns_name + label_re = re.compile(r'(?P