reusable-gitops-pr.yaml

---
name: GitOps PR

on:  
  # REUSABLE WORKFLOW with INPUTS
  # to keep this workflow simple, assumptions are made:
    # - Checks out a repo with a kustomization.yaml file
    # - Changes a image tag in the kustomization.yaml file
    # - Creates a new branch and a PR with the change
    # - Optionally notifies a Slack channel

  workflow_call:
    # allow reuse of this workflow in other repos
    inputs:
      repo:
        description: Kustomize repo to checkout
        required: true
        type: string
        # default: org/repo
      image:
        description: Image name to update in Kustomize
        required: true
        type: string
        # default: ghcr.io/org/repo
      tag:
        description: New tag to use for the image
        required: true
        type: string
      # relative path to the directory with the kustomization.yaml file
      kustomize-path:
        description: Path to the kustomization.yaml file
        required: true
        type: string
        # default: environments/staging01
      slack-channel-id:
        description: Slack channel ID to post to
        required: false
        type: string
        # default: C0123456789

    secrets:
      slack-token:
        description: Docker Hub username
        required: false
      github-token:
        description: Docker Hub token with write access to the repo and PRs
        required: true

    outputs:
      pr-url:
        description: "The newly created GitHub Pull Request URL"
        value: ${{ jobs.gitops-pr.outputs.pr-url }}

# permissions: GITHUB_TOKEN are better set by the **calling** workflow
# but we'll set defaults here for reference
# https://docs.github.com/en/actions/using-workflows/workflow-syntax-for-github-actions#jobsjob_idpermissions
permissions: write-all

jobs:
  gitops-pr:

    name: Update image tag

    runs-on: ubuntu-latest

    outputs:

      pr-url: ${{ steps.cpr.outputs.pull-request-url }}

    steps:
          
      - name: Checkout ${{ inputs.repo }}
        uses: actions/checkout@v4
        with:
          repository: ${{ inputs.repo }}
          token: ${{ secrets.github-token }}

      - name: Change image tag in kustomization.yaml
        run: |
          cd ${{ inputs.kustomize-path }}
          kustomize edit set image "$(echo '${{ inputs.image }}' | tr '[:upper:]' '[:lower:]'):${{ inputs.tag }}"
          cat kustomization.yaml

      - name: Create Pull Request
        id: cpr
        uses: peter-evans/create-pull-request@v7
        with:
          token: ${{ secrets.github-token }}
          commit-message: "Update image for ${{ inputs.kustomize-path }}"
          title: "${{ inputs.kustomize-path }} image update to: ${{ inputs.image }}:${{ inputs.tag }}"
          body: "Update image tag of file `${{ inputs.kustomize-path }}/kustomization.yaml` to `${{ inputs.image }}:${{ inputs.tag }}`"
          branch: "${{ inputs.tag }}"
      
      - name: Post to a Slack channel
        id: slack
        if: ${{ inputs.slack-channel-id }}
        uses: slackapi/slack-github-action@v1
        with:
          channel-id: ${{ inputs.slack-channel-id }}
          slack-message: "PR created ${{ steps.cpr.outputs.pull-request-url }}"
        env:
          SLACK_BOT_TOKEN: ${{ secrets.slack-token }}