Using Helm charts in Commodore components

It’s considered best practice to expose Helm chart values to the user by introducing a component parameter helm_values.

This minimizes the need for duplicated parameters between the Helm chart default values and the component default parameters.

Additionally, it’s considered best practice to expose the Helm chart versions and sources for all charts used by the component in parameter charts. The value of this parameter should be an object, where each field corresponds to a Helm chart name and the value is another object with fields source and version indicating the chart repository and version to use for that chart.

For Renovate to be able to extract the depedency, the keys in parameter charts must match the corresponding Helm chart names exactly.

Example

In this example the component configures some different default values for chart my-chart.

class/defaults.yml

parameters:
  my_component:
    namespace: syn-my-component
    charts:
      my-chart: (1)
        source: https://charts.appuio.ch/
        version: v1.2.3
    helm_values: (2)
      valueA: 2
      valueB: 'five'

1	The Helm chart source and version for chart `my-chart`. The key must match the chart’s name for Renovate to be able to generate update PRs.
2	Configure default values for Helm values where the chart defaults aren’t a good fit for the component. Users can provide arbitrary further Helm values by adding them to parameter `helm_values`.

In the component class:

class/my-component.yml

parameters:
  kapitan:
    dependencies:
      - type: helm
        source: ${my_component:charts:my-chart:source}
        chart_name: my-chart (1)
        version: ${my_component:charts:my-chart:version}
    compile:
      - input_paths:
          - my-component/helmcharts/my-chart/${my_component:charts:my-chart:version}
        input_type: helm
        output_type: yaml
        output_path: my-component/01_helmchart
        helm_values: ${my_component:helm_values} (2)
        helm_params: (3)
          name: syn-my-chart
          namespace: ${my_component:namespace}

1	The Helm chart name. This value must match the key in parameter `charts`.
2	Pass through Helm values from component parameters.
3	Configure Helm release name and namespace.