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ClickHouse Installation Custom Resource explained

Let's describe in details ClickHouse Custom Resource
Full example is available in 99-clickhouseinstallation-max.yaml file.
The best way to work with this doc is to open 99-clickhouseinstallation-max.yaml in separate tab and look into it along with reading this explanation.

apiVersion: "clickhouse.altinity.com/v1"
kind: "ClickHouseInstallation"
metadata:
  name: "clickhouse-installation-test"

Create resource of kind: "ClickHouseInstallation" named as "clickhouse-installation-max". Accessible with kubectl as:

kubectl get clickhouseinstallations.clickhouse.altinity.com 
NAME                           AGE
clickhouse-installation-max   23h

.spec.defaults

  defaults:
    replicasUseFQDN: "no"
    distributedDDL:
      profile: default
    templates:
      podTemplate: clickhouse-v18.16.1
      dataVolumeClaimTemplate: default-volume-claim
      logVolumeClaimTemplate: default-volume-claim
      serviceTemplate: chi-service-template

.spec.defaults section represents default values for sections below.

  • .spec.defaults.replicasUseFQDN - should replicas be specified by FQDN in <host></host>
  • .spec.defaults.distributedDDL - reference to <yandex><distributed_ddl></distributed_ddl></yandex>
  • .spec.defaults.templates would be used everywhere where templates is needed.

.spec.configuration

  configuration:

.spec.configuration section represents sources for ClickHouse configuration files. Be it users, remote servers and etc configuration files.

.spec.configuration.zookeeper

    zookeeper:
      nodes:
        - host: zookeeper-0.zookeepers.zoo3ns.svc.cluster.local
          port: 2181
        - host: zookeeper-1.zookeepers.zoo3ns.svc.cluster.local
          port: 2181
        - host: zookeeper-2.zookeepers.zoo3ns.svc.cluster.local
          port: 2181
      session_timeout_ms: 30000
      operation_timeout_ms: 10000
      root: /path/to/zookeeper/node
      identity: user:password

.spec.configuration.zookeeper refers to <yandex><zookeeper></zookeeper></yandex> config section

.spec.configuration.profiles

.spec.configuration.profiles refers to <yandex><profiles></profiles></yandex> settings sections.

    profiles:
      readonly/readonly: 1

expands into

      <profiles>
        <readonly>
          <readonly>1</readonly>
        </readonly>
      </profiles>

.spec.configuration.quotas

.spec.configuration.quotas refers to <yandex><quotas></quotas></yandex> settings sections.

    quotas:
      default/interval/duration: 3600
      default/interval/queries: 10000

expands into

      <quotas>
        <default>
          <interval>
              <duration>3600</duration>
              <queries>3600</queries>
          </interval>
        </default>
      </quotas>

.spec.configuration.users

.spec.configuration.users refers to <yandex><users></users></yandex> settings sections.

  users:
    test/networks/ip:
        - "127.0.0.1"
        - "::/0"

expands into

     <users>
        <test>
          <networks>
            <ip>127.0.0.1</ip>
            <ip>::/0</ip>
          </networks>
        </test>
     </users>

when you skip user/password, or setup it as empty value then chConfigUserDefaultPassword parameter value from etc-clickhouse-operator-files ConfigMap will use.

.spec.configuration.settings

    settings:
      compression/case/method: "zstd"
#      <compression>
#       <case>
#         <method>zstd</method>
#      </case>
#      </compression>

.spec.configuration.settings refers to <yandex><profiles></profiles><users></users></yandex> settings sections.

.spec.configuration.files

    files:
      dict1.xml: |
        <yandex>
            <!-- ref to file /etc/clickhouse-data/config.d/source1.csv -->
        </yandex>
      source1.csv: |
        a1,b1,c1,d1
        a2,b2,c2,d2

.spec.configuration.files allows to introduce custom files to ClickHouse via YAML manifest. This can be used in order to create complex custom configurations. One possible usage example is external dictionary

spec:
  configuration:
    settings:
      dictionaries_config: config.d/*.dict
    files:
      dict_one.dict: |
        <yandex>
          <dictionary>
        <name>one</name>
        <source>
            <clickhouse>
                <host>localhost</host>
                <port>9000</port>
                <user>default</user>
                <password/>
                <db>system</db>
                <table>one</table>
            </clickhouse>
        </source>
        <lifetime>60</lifetime>
        <layout><flat/></layout>
        <structure>
            <id>
                <name>dummy</name>
            </id>
            <attribute>
                <name>one</name>
                <expression>dummy</expression>
                <type>UInt8</type>
                <null_value>0</null_value>
            </attribute>
        </structure>
        </dictionary>
        </yandex>

.spec.configuration.clusters

    clusters:

.spec.configuration.clusters represents array of ClickHouse clusters definitions.

Clusters and Layouts

ClickHouse instances layout within cluster is described with .clusters.layout section

      - name: all-counts
        templates:
          podTemplate: clickhouse-v18.16.1
          dataVolumeClaimTemplate: default-volume-claim
          logVolumeClaimTemplate: default-volume-claim
        layout:
          shardsCount: 3
          replicasCount: 2

Pod and VolumeClaim templates to be used can be specified explicitly for each replica:

        templates:
          podTemplate: clickhouse-v18.16.1
          dataVolumeClaimTemplate: default-volume-claim
          logVolumeClaimTemplate: default-volume-claim

layout is specified with basic layout dimensions:

        layout:
          shardsCount: 3
          replicasCount: 2

or with detailed specification of shards and replicas.
shard0 here has replicasCount specified, while shard1 has 3 replicas explicitly specified, with possibility to customized each replica.

      - name: customized
        templates:
          podTemplate: clickhouse-v18.16.1
          dataVolumeClaimTemplate: default-volume-claim
          logVolumeClaimTemplate: default-volume-claim
        layout:
          shards:
            - name: shard0
              replicasCount: 3
              weight: 1
              internalReplication: Disabled
              templates:
                podTemplate: clickhouse-v18.16.1
                dataVolumeClaimTemplate: default-volume-claim
                logVolumeClaimTemplate: default-volume-claim

            - name: shard1
              templates:
                podTemplate: clickhouse-v18.16.1
                dataVolumeClaimTemplate: default-volume-claim
                logVolumeClaimTemplate: default-volume-claim
              replicas:
                - name: replica0
                - name: replica1
                - name: replica2

combination is also possible, which is presented in shard2 specification, where 3 replicas in total are requested with replicasCount and one of these replicas is explicitly specified with different podTemplate:

      - name: customized
        templates:
          podTemplate: clickhouse-v18.16.1
          dataVolumeClaimTemplate: default-volume-claim
          logVolumeClaimTemplate: default-volume-claim
        layout:
          shards:
          
            - name: shard2
              replicasCount: 3
              templates:
                podTemplate: clickhouse-v18.16.1
                dataVolumeClaimTemplate: default-volume-claim
                logVolumeClaimTemplate: default-volume-claim
              replicas:
                - name: replica0
                  port: 9000
                  templates:
                    podTemplate: clickhouse-v19.11.3.11
                    dataVolumeClaimTemplate: default-volume-claim
                    logVolumeClaimTemplate: default-volume-claim

ClickHouse cluster named all-counts represented by layout with 3 shards of 2 replicas each (6 pods total). Pods will be created and fully managed by the operator. In ClickHouse config file this would be represented as:

<yandex>
    <remote_servers>
        <all-counts>
        
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.1.1</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>192.168.1.2</host>
                    <port>9000</port>
                </replica>
            </shard>
            
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.1.3</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>192.168.1.4</host>
                    <port>9000</port>
                </replica>
            </shard>
            
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.1.5</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>192.168.1.6</host>
                    <port>9000</port>
                </replica>
            </shard>
            
        </all-counts>
    </remote_servers>
</yandex>

with full IP and DNS management provided by k8s and operator.

Layout with shards count specified

    - name: shards-only
      layout:
        shardsCount: 3 # replicasCount = 1, by default

ClickHouse cluster named shards-only represented by layout with 3 shards of 1 replicas each (3 pods total). Pods will be created and fully managed by the operator. In ClickHouse config file this would be represented as:

<yandex>
    <remote_servers>
        <shards-only>
        
            <shard>
                <replica>
                    <host>192.168.1.1</host>
                    <port>9000</port>
                </replica>
            </shard>
            
            <shard>
                <replica>
                    <host>192.168.1.2</host>
                    <port>9000</port>
                </replica>
            </shard>
            
            <shard>
                <replica>
                    <host>192.168.1.3</host>
                    <port>9000</port>
                </replica>
            </shard>
            
        </shards-only>
    </remote_servers>
</yandex>

Layout with replicas count specified

    - name: replicas-only
      layout:
        replicasCount: 3 # shardsCount = 1, by default

ClickHouse cluster named replicas-only represented by layout with 1 shard of 3 replicas each (3 pods total). Pods will be created and fully managed by the operator. In ClickHouse config file this would be represented as:

<yandex>
    <remote_servers>
        <replicas-only>
        
            <shard>
                <internal_replication>true</internal_replication>
                <replica>
                    <host>192.168.1.1</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>192.168.1.2</host>
                    <port>9000</port>
                </replica>
                <replica>
                    <host>192.168.1.3</host>
                    <port>9000</port>
                </replica>
            </shard>
            
        </replicas-only>
    </remote_servers>
</yandex>

Advanced layout techniques

layout provides possibility to explicitly define each shard and replica with .spec.configuration.clusters.layout.shards

    - name: customized
      layout:
        shards:
          - replicas:

so we can specify shards and replicas explicitly - either all shards and replias or selectively, only those which we'd like to be different from default template.

Full specification of replicas in a shard. Note - no replicasCount specified, all replicas are described by replicas array:

            - name: shard1
              templates:
                podTemplate: clickhouse-v18.16.1
                dataVolumeClaimTemplate: default-volume-claim
                logVolumeClaimTemplate: default-volume-claim
              replicas:
                - name: replica0
                - name: replica1
                - name: replica2

Another example with selectively described replicas. Note - replicasCount specified and one replica is described explicitly

            - name: shard2
              replicasCount: 3
              templates:
                podTemplate: clickhouse-v18.16.1
                dataVolumeClaimTemplate: default-volume-claim
                logVolumeClaimTemplate: default-volume-claim
              replicas:
                - name: replica0
                  port: 9000
                  templates:
                    podTemplate: clickhouse-v19.11.3.11
                    dataVolumeClaimTemplate: default-volume-claim
                    logVolumeClaimTemplate: default-volume-claim

.spec.templates.serviceTemplates

  templates:
    serviceTemplates:
      - name: chi-service-template
        # generateName understands different sets of macros,
        # depending on the level of the object, for which Service is being created:
        # For CHI/CHK-level Service:
        # {chi} - ClickHouseInstallation name
        # {chk} - ClickHouseKeeperInstallation name
        # {chiID} - short hashed ClickHouseInstallation name 
        # {chkID} - short hashed ClickHouseKeeperInstallation name
        #
        # For Cluster-level Service:
        # {chi} - ClickHouseInstallation name
        # {chk} - ClickHouseKeeperInstallation name
        # {chiID} - short hashed ClickHouseInstallation name
        # {chkID} - short hashed ClickHouseKeeperInstallation name
        # {cluster} - cluster name
        # {clusterID} - short hashed cluster name (BEWARE, this is an experimental feature)
        # {clusterIndex} - 0-based index of the cluster in the CHI (BEWARE, this is an experimental feature)
        #
        # For Shard-level Service:
        # {chi} - ClickHouseInstallation name
        # {chk} - ClickHouseKeeperInstallation name
        # {chiID} - short hashed ClickHouseInstallation name
        # {chkID} - short hashed ClickHouseKeeperInstallation name
        # {cluster} - cluster name
        # {clusterID} - short hashed cluster name (BEWARE, this is an experimental feature)
        # {clusterIndex} - 0-based index of the cluster in the CHI
        # {shard} - shard name
        # {shardID} - short hashed shard name (BEWARE, this is an experimental feature)
        # {shardIndex} - 0-based index of the shard in the cluster 
        #
        # For Replica-level Service:
        # {chi} - ClickHouseInstallation name
        # {chk} - ClickHouseKeeperInstallation name
        # {chiID} - short hashed ClickHouseInstallation name
        # {chkID} - short hashed ClickHouseKeeperInstallation name
        # {cluster} - cluster name
        # {clusterID} - short hashed cluster name 
        # {clusterIndex} - 0-based index of the cluster in the CHI 
        # {shard} - shard name
        # {shardID} - short hashed shard name (BEWARE, this is an experimental feature)
        # {shardIndex} - 0-based index of the shard in the cluster 
        # {replica} - replica name
        # {replicaID} - short hashed replica name 
        # {replicaIndex} - 0-based index of the replica in the shard 
        generateName: "service-{chi}"
        # type ObjectMeta struct from k8s.io/meta/v1
        metadata:
          labels:
            custom.label: "custom.value"
          annotations:
            cloud.google.com/load-balancer-type: "Internal"
            service.beta.kubernetes.io/aws-load-balancer-internal: 0.0.0.0/0
            service.beta.kubernetes.io/azure-load-balancer-internal: "true"
            service.beta.kubernetes.io/openstack-internal-load-balancer: "true"
            service.beta.kubernetes.io/cce-load-balancer-internal-vpc: "true"
        # type ServiceSpec struct from k8s.io/core/v1
        spec:
          ports:
            - name: http
              port: 8123
            - name: client
              port: 9000
          type: LoadBalancer

.spec.templates.serviceTemplates represents Service templates with additional sections, such as:

  1. generateName

generateName is used to explicitly specify service name to be created. generateName provides the following macro substitutions:

  1. {chi} - ClickHouseInstallation name
  2. {chiID} - short hashed ClickHouseInstallation name (BEWARE, this is an experimental feature)
  3. {cluster} - cluster name
  4. {clusterID} - short hashed cluster name (BEWARE, this is an experimental feature)
  5. {clusterIndex} - 0-based index of the cluster in the CHI (BEWARE, this is an experimental feature)
  6. {shard} - shard name
  7. {shardID} - short hashed shard name (BEWARE, this is an experimental feature)
  8. {shardIndex} - 0-based index of the shard in the cluster (BEWARE, this is an experimental feature)
  9. {replica} - replica name
  10. {replicaID} - short hashed replica name (BEWARE, this is an experimental feature)
  11. {replicaIndex} - 0-based index of the replica in the shard (BEWARE, this is an experimental feature)

.spec.templates.volumeClaimTemplates

  templates:
    volumeClaimTemplates:
      - name: default-volume-claim
        # type PersistentVolumeClaimSpec struct from k8s.io/core/v1
        spec:
          # 1. If storageClassName is not specified, default StorageClass
          # (must be specified by cluster administrator) would be used for provisioning
          # 2. If storageClassName is set to an empty string (‘’), no storage class will be used
          # dynamic provisioning is disabled for this PVC. Existing, “Available”, PVs
          # (that do not have a specified storageClassName) will be considered for binding to the PVC
          #storageClassName: gold
          accessModes:
            - ReadWriteOnce
          resources:
            requests:
              storage: 1Gi

.spec.templates.volumeClaimTemplates represents PersistentVolumeClaim templates

.spec.templates.podTemplates

  templates:
    podTemplates:
      # multiple pod templates makes possible to update version smoothly
      # pod template for ClickHouse v18.16.1
      - name: clickhouse-v18.16.1
        # We may need to label nodes with clickhouse=allow label for this example to run
        # See ./label_nodes.sh for this purpose
        zone:
          key: "clickhouse"
          values:
            - "allow"
        # Shortcut version for AWS installations
        #zone:
        #  values:
        #    - "us-east-1a"

        # Possible values for distribution are:
        # Unspecified
        # OnePerHost
        distribution: "Unspecified"

        # type PodSpec struct {} from k8s.io/core/v1
        spec:
          containers:
            - name: clickhouse
              image: clickhouse/clickhouse-server:23.8
              volumeMounts:
                - name: default-volume-claim
                  mountPath: /var/lib/clickhouse
              resources:
                requests:
                  memory: "64Mi"
                  cpu: "100m"
                limits:
                  memory: "64Mi"
                  cpu: "100m"

.spec.templates.podTemplates represents Pod Templates with additional sections, such as:

  1. zone
  2. distribution

zone and distribution together define zoned layout of ClickHouse instances over nodes. Internally it is a shortcut to affinity.nodeAffinity and affinity.podAntiAffinity properly filled.

Example - how to place ClickHouse instances in AWS us-east-1a availability zone with one ClickHouse per host

        zone:
          values:
            - "us-east-1a"
        distribution: "OnePerHost"

Example - how to place ClickHouse instances on nodes labeled as clickhouse=allow with one ClickHouse per host

        zone:
          key: "clickhouse"
          values:
            - "allow"
        distribution: "OnePerHost"