docker-image.yml

name: Docker Image CI

on:
#  schedule:
#    - cron: '23 0 * * *'
  push:
    branches: [ "master" ]
  pull_request:
    branches: [ "master" ]


env:
  # Use docker.io for Docker Hub if empty
  REGISTRY: ghcr.io
  # github.repository as <account>/<repo>
  IMAGE_NAME: ${{ github.repository }}


jobs:

  build:

    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      # This is used to complete the identity challenge
      # with sigstore/fulcio when running outside of PRs.
      id-token: write

    steps:
    
    - name: Checkout repository
      uses: actions/checkout@v4.2.1

    # Install the cosign tool except on PR
    # https://github.com/sigstore/cosign-installer
    - name: Install cosign
      if: github.event_name != 'pull_request'
      uses: sigstore/cosign-installer@v3.7.0


    # Set up BuildKit Docker container builder to be able to build
    # multi-platform images and export cache
    # https://github.com/docker/setup-buildx-action
    - name: Set up Docker Buildx
      uses: docker/setup-buildx-action@v3.7.1

    # Login against a Docker registry except on PR
    # https://github.com/docker/login-action
    - name: Log into registry ${{ env.REGISTRY }}
      if: github.event_name != 'pull_request'
      uses: docker/login-action@v3.3.0
      with:
        registry: ${{ env.REGISTRY }}
        username: ${{ github.actor }}
        password: ${{ secrets.GITHUB_TOKEN }}


    # Extract metadata (tags, labels) for Docker
    # https://github.com/docker/metadata-action
    - name: Extract Docker metadata
      id: meta
      uses: docker/metadata-action@v5.5.1
      with:
        images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
                
    - uses: ScribeMD/docker-cache@0.5.0
      name: Cache Docker images
      with:
        key: docker-${{ runner.os }}
        
    # Build and push Docker image with Buildx (don't push on PR)
    # https://github.com/docker/build-push-action
    - name: Build and push Docker image
      id: build-and-push
      uses: docker/build-push-action@v6.9.0
      with:
        context: .
        push: ${{ github.event_name != 'pull_request' }}
        tags: ${{ steps.meta.outputs.tags }}
        labels: ${{ steps.meta.outputs.labels }}
        cache-from: type=gha
        cache-to: type=gha,mode=max 

    # Sign the resulting Docker image digest except on PRs.
    # This will only write to the public Rekor transparency log when the Docker
    # repository is public to avoid leaking data.  If you would like to publish
    # transparency data even for private images, pass --force to cosign below.
    # https://github.com/sigstore/cosign
    - name: Sign the published Docker image
      if: ${{ github.event_name != 'pull_request' }}
      env:
        # https://docs.github.com/en/actions/security-guides/security-hardening-for-github-actions#using-an-intermediate-environment-variable
        TAGS: ${{ steps.meta.outputs.tags }}
        DIGEST: ${{ steps.build-and-push.outputs.digest }}
      # This step uses the identity token to provision an ephemeral certificate
      # against the sigstore community Fulcio instance.
      run: echo "${TAGS}" | xargs -I {} cosign sign --yes {}@${DIGEST}