docker-build.yaml

name: "Build docker images"

on:
  push:
    branches:
      - "master"
  schedule:
    - cron: "0 5 * * 4"

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

jobs:
  build:
    runs-on: "ubuntu-latest"
    strategy:
      matrix:
        context:
          - traefik
          - nextcloud-web
          - nextcloud-fpm

    steps:
      - uses: "actions/checkout@v4"

      - name: "Install cosign"
        uses: "sigstore/cosign-installer@v3.7.0"

      - uses: "docker/setup-buildx-action@v3.7.1"

      # Login against a Docker registry except on PR
      # https://github.com/docker/login-action
      - uses: "docker/login-action@v3.3.0"
        with:
          registry: "ghcr.io"
          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: "ghcr.io/${{ github.repository }}/${{ matrix.context }}"
          tags: |
            # set latest tag for master branch
            type=raw,value=latest,enable=${{ github.ref == format('refs/heads/{0}', 'master') }}

      # 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: "docker/${{ matrix.context }}"
          push: true
          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
        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}