Base Chart

This Helm Chart is a base chart that includes helpers/templates. The main goal is to make it easier to build/maintain Helm Charts of micro-services deployed on k8s.

Contents

• Getting Started
• Development
• Chart Testing
• Included Features
  • Liveness/Readiness Probes
  • Autoscaling
  • PodDisruptionBudget
  • Metrics
  • SLO
• Contributing
• Support

Getting Started

1. Create a folder for your chart with a Chart.yaml
2. Include this chart as a dependency

   dependencies:
     - name: base
       version: ~>1.0.0
       repository: oci://ghcr.io/wdaan/base-chart

3. Copy the following into templates/manifest.yaml

   {{ include "base.all" . }}
   

4. Run helm dep update
5. Create a values.yaml-file and configure as desired, see charts/myservice/tests/deployment-full.yaml or the other test files for example configurations.

Take a look at the example chart

Development

• cd CHARTDIR
• helm dep build
• cd ..
• helm template MY_CHARTD_DIR

Chart Testing

The charts/myservice/tests-folder contains a couple of values files. All of these are different configurations are tested against the base chart on every PR.

Included Features

This chart includes most of the basic stuff you'd need when deploying a service to k8s. If you take a look at the minimal-configuration, you'll notice that you don't need a lot to get started and most of those are self-explanatory. However there are some components that might require a little explananation

Liveness/Readiness Probes

Probes are a great way to determine if your service is able to serve traffic, running properly or is safe to be removed/added to a target group (when running on EKS). See an example configuration below.

probes:
  liveness:
    enabled: true
    path: /
  readiness:
    enabled: true
    path: /
    initialDelaySeconds: 15
    timeoutSeconds: 10

Autoscaling

You can configure autoscaling with the following properties

autoscaling:
  enabled: true
  minReplicas: 2
  maxReplicas: 1000
  targetCPUUtilizationPercentage: 80%
  targetMemoryUtilizationPercentage: 80%

You can't go below 2 for minReplicas because 1 instance cannot guarantee uptime when rotating nodes of your cluster.

PodDisruptionBudget

To further guarantee the availability of your service you can enabled the pdb. With 50% for 2 nodes, 1 instance is guaranteed to be available and nodes will drain accordingly.

pdb:
  enabled: true
  maxUnavailable: 50%

Metrics

You can allow Prometheus to discover your service to allow for metric scraping. You can do that by enabling the serviceMonitor. This will only work if you're running the Prometheus operator. If you're not, you can use useAnnotations, which will annotate the service of your application with prometheus.io/scrape: "true" etc.

metrics:
  useAnnotations: true # to use legacy annotations on your service
  serviceMonitor:
    enabled: true
  # path: /mypath => defaults t /metrics
  # port: 12345 => defaults to svc port
 

SLO

For generating our SLOs we rely on sloth.io. It provides some easy wrapping on generating Prometheus rules/alerts.

metrics:
  slo:
  enabled: true
  slos:
  - name: requests-availability
    query: sum(rate(app_request_duration_milliseconds_count{service="myservice",code=~"(5..|429)"}[.window]))
    totalQuery: sum(rate(app_request_duration_milliseconds_count{service="myservice"}[.window]))
    objective: 0.99
    alerting:
      enabled: true
      name: MyServiceHighErrorRate
      labels:
        severity: warning
        owner: myservice
      title: High error rate on request responses
  - name: requests-latency
    query: |
      (
        sum(rate(app_request_duration_milliseconds_count{service="myservice"}[.window]))
        -
        sum(rate(app_request_duration_milliseconds_bucket{le="300",service="myservice"}[.window]))
      )
    totalQuery: sum(rate(app_request_duration_milliseconds_count{service="myservice"}[.window]))
    objective: 0.999

This enables the 2 default SLO's:

• request latency
• request availability

Please replace myservice with the name of your service. Enable alerting as desired.

.window is a placeholder that will be replaced during templating, replacing .window with e.g. 5m should be a valid and working query!

For non-urgent/critical alerts you can set disableCritical to true.

Objective is the percentage of requests that should succeed:

• 0.99 => 99% of requests should succeed, so 10 out of 1000 is allowed to fail
• 0.999 => 99.9% of requests should succeed, so 1 out of 1000 is allowed fail

Feel free to add any other custom SLO's if required.

Contributing

I'll gladly accept help/pull requests & advice!

Support

Open up an issue 😛

but before you do that:

• confirm you're using the latest version
• confirm there is no other issue mentioning the same problem