# The way this works is the following:
#
# The publish-docker-image job runs when a release is created, hence after post-release job.
# The steps are:
#  - Log in to the Container registry (example: ghcr.io/create-ci).
#  - Extract metadata (tags, labels) for Docker image.
#  - Build and push Docker image to the container registry.
#    Image tags are "latest" and the semver tag (without the "v" prefix).
#  - Generate artifact attestation.
#
# Reference:
# https://docs.github.com/en/actions/use-cases-and-examples/publishing-packages/publishing-docker-images#publishing-images-to-github-packages

name: publish-docker-image
on:
  workflow_run:
    workflows: [post-release]
    types:
      - completed

env:
  REGISTRY: ghcr.io
  IMAGE_NAME: ${{ github.repository }}

jobs:
  build-and-push-image:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      attestations: write
      id-token: write
    steps:
      - name: Checkout repository
        uses: actions/checkout@v4
        with:
          fetch-tags: true

      - name: Log in to the Container registry
        uses: docker/login-action@65b78e6e13532edd9afa3aa52ac7964289d1a9c1
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      # docker/metadata-action extracts the tag from the event that triggered the workflow.
      # Since the workflow was triggered by another workflow, the tag is the branch name (e.g. master).
      # Use `git tag --merged $branch` to get the semver tag for the docker image.
      - name: Extract tag from master
        run: echo "TAG=$(git tag --merged ${{ github.ref_name }})" >> $GITHUB_ENV

      - name: Extract metadata (tags, labels) for Docker
        id: meta
        uses: docker/metadata-action@9ec57ed1fcdbf14dcef7dfbe97b2010124a938b7
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=semver,pattern={{version}},value=${{ env.TAG }}
            type=raw,value=latest,enable={{is_default_branch}}

      - name: Build and push Docker image
        id: push
        uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
        with:
          context: .
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}

      - name: Generate artifact attestation
        uses: actions/attest-build-provenance@v2
        with:
          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME}}
          subject-digest: ${{ steps.push.outputs.digest }}
          push-to-registry: true