giantswarm / helm-values-gen

Helm plugin 'values-gen' generates the default values file based of values.schema.json

helm-values-gen

helm-values-gen generates a YAML payload that contains all default values in a given JSON schema. This is useful when maintaining a helm project with a values.schema.json that already contains the default values that are expected in values.yaml.

Installation

Currently, helm-values-gen can be installed as Go binary. In the future it will be (additionally) possible to install it as a helm plugin.

go install github.com/giantswarm/helm-values-gen@latest

Usage

$ helm-values-gen values.schema.json -o values.yaml

Wrote default values to values.yaml

Use --help to learn about more options.

Details

As JSON schemas can be nested deeply, we need to define which default values will be contained in the resulting payload. The tool follows these steps:

1. Start in the root of the schema
2. If there is a default value, add it to the payload.
3. Recurse into all properties.

Note: The tool does not recurse into the items keyword of an array. To specify default values for an array you have to set a default on the level of the array.

Consider the following example:

values.schema.json

{
  "type": "object",
  "properties": {
    "addresses": {
      "type": "array",
      "items": {
        "type": "object",
        "properties": {
          "city": {
            "type": "string",
            "default": "New York"
          }
        }
      },
    },
    "lastName": {
      "type": "string",
      "default": "Doe"
    }
  }
}

values.yaml

lastName: Doe

The default value addresses[].city = "New York" is not reflected in values.yaml.

To specify a default value for an array consider the following example:

{
  "type": "object",
  "properties": {
    "addresses": {
      "type": "array",
      "items": {
        "type": "object"
        "properties": {
          "city": {
            "type": "string",
            "default": "New York"
          }
        }
      },
      "default": [
        {
          "city": "New York"
        }
      ]
    },
    "lastName": {
      "type": "string",
      "default": "Doe"
    }
  }
}

values.yaml

addresses:
  - city: New York
lastName: Doe

GitHub Action

An action to run schemalint verify on the values.schema.json in app repositories in provided in actions/verify-helm-schema.

Example workflow:

name: JSON schema validation
on:
  push: {}

jobs:
  generate:
    name: Check that values.yaml is generated from values.schema.json with helm-values-gen
    runs-on: ubuntu-latest
    steps:
      - name: Checkout code
        uses: actions/checkout@v3

      - name: Run helm-values-gen
        id: run-helm-values-gen
        uses: giantswarm/helm-values-gen/actions/ensure-generated@v1

Major Releases

This repository uses floating tags. Other repositories that use helm-values-gen point to major floating tag versions, like v1. That means that all minor and patch releases will be automatically rolled out to these repositories. When doing a major release the following steps have to be completed:

1. Create a new major floating tag under "Actions -> Ensure major version tags -> Run Workflow"
2. Update all references to schemalint.
   1. devctl: pkg/gen/input/workflows/internal/file/cluster_app_schema_validation.yaml.template