name: Publish Docker Image

# This workflow uses actions that are not certified by GitHub.
# They are provided by a third-party and are governed by
# separate terms of service, privacy policy, and support
# documentation.

on:
    push:
        branches: ["main"]
        # Publish semver tags as releases.
        tags: ["v*.*.*"]

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@v3

            # Install the cosign tool
            # https://github.com/sigstore/cosign-installer
            - name: Install cosign
              uses: sigstore/cosign-installer@6e04d228eb30da1757ee4e1dd75a0ec73a653e06 #v3.1.1
              with:
                  cosign-release: "v2.1.1"

            # 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@f95db51fddba0c2d1ec667646a06c2ce06100226 # v3.0.0

            # Login against a Docker registry
            # https://github.com/docker/login-action
            - name: Log into registry ${{ env.REGISTRY }}
              uses: docker/login-action@343f7c4344506bcbf9b4de18042ae17996df046d # v3.0.0
              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@96383f45573cb7f253c731d3b3ab81c87ef81934 # v5.0.0
              with:
                  images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

            # 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@0565240e2d4ab88bba5387d719585280857ece09 # v5.0.0
              with:
                  context: .
                  tags: ${{ steps.meta.outputs.tags }}
                  labels: ${{ steps.meta.outputs.labels }}
                  platforms: linux/amd64,linux/arm64
                  cache-from: type=gha
                  cache-to: type=gha,mode=max

            # Sign the resulting Docker image digest
            # 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}