linkchecker/.github/workflows/publish-docker.yml

# https://docs.github.com/en/packages/managing-github-packages-using-github-actions-workflows/publishing-and-installing-a-package-with-github-actions#publishing-a-package-using-an-action

name: Create and publish a Docker image

on:
  push:
    branches: ['master']
    tags: 'v*'
  workflow_dispatch:

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

jobs:
  build-and-push-image:
    runs-on: ubuntu-latest
    permissions:
      attestations: write
      contents: read
      id-token: write
      packages: write

    steps:
      - name: Log in to the Container registry
        uses: docker/login-action@e92390c5fb421da1463c202d546fed0ec5c39f20  # v3.10
        with:
          registry: ${{ env.REGISTRY }}
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Extract metadata (tags, labels) for Docker
        id: meta
        uses: docker/metadata-action@8e5442c4ef9f78752691e2d8f8d19755c6f78e81  # v5.5.1
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          flavor: latest=true
          tags: |
            type=semver,pattern={{version}}
            type=ref,event=branch            

      - name: Build and push Docker image
        id: push
        uses: docker/build-push-action@2cdde995de11925a030ce8070c3d77a52ffcf1c0  # v5.3.0
        with:
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}

      - name: Attest
        uses: actions/attest-build-provenance@v1
        with:
          subject-name: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          subject-digest: ${{ steps.push.outputs.digest }}
          push-to-registry: true

      - name: Delete oldest Docker images
        uses: actions/delete-package-versions@v5
        with:
          package-name: 'linkchecker'
          package-type: 'container'
          min-versions-to-keep: 20
          delete-only-untagged-versions: 'true'