pl_mail/.github/workflows/docker.yml

name: Build and push Docker image

on:
    push:
        branches: [main]
        # Releases. `latest` moves only when one of these is pushed — see the
        # tag rules in the merge job.
        tags: ['v*']
    pull_request:
        branches: [main]

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

jobs:
    # One job per architecture, each on a runner of that architecture. The prod
    # stage runs composer install, dump-autoload, tailwind:build --minify and
    # asset-map:compile — all CPU-bound PHP, which is why this is a matrix of
    # native runners rather than a single job cross-building under QEMU.
    #
    # Neither job pushes a tag. Both push an untagged digest, and `merge` below
    # assembles them into the one manifest list the tags point at.
    build:
        runs-on: ${{ matrix.runner }}
        strategy:
            fail-fast: false
            matrix:
                include:
                    - platform: linux/amd64
                      arch: amd64
                      runner: ubuntu-latest
                    - platform: linux/arm64
                      arch: arm64
                      runner: ubuntu-24.04-arm
        permissions:
            contents: read
            packages: write

        steps:
            - name: Checkout
              uses: actions/checkout@v4

            - name: Set up Buildx
              uses: docker/setup-buildx-action@v3

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

            # Labels only. Tags belong to the manifest list, which does not
            # exist until the merge job runs.
            - name: Extract metadata
              id: meta
              uses: docker/metadata-action@v5
              with:
                  images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}

            - name: Build and push by digest
              id: build
              uses: docker/build-push-action@v6
              with:
                  context: .
                  target: frankenphp_prod
                  platforms: ${{ matrix.platform }}
                  labels: ${{ steps.meta.outputs.labels }}
                  provenance: false
                  outputs: type=image,name=${{ env.REGISTRY }}/${{ env.IMAGE_NAME }},push-by-digest=true,name-canonical=true,push=${{ github.event_name != 'pull_request' }}
                  # Scoped per architecture: a shared scope would have the two
                  # jobs evicting each other's layers on every run.
                  cache-from: type=gha,scope=frankenphp_prod-${{ matrix.arch }}
                  cache-to: type=gha,mode=max,scope=frankenphp_prod-${{ matrix.arch }}

            - name: Export digest
              if: github.event_name != 'pull_request'
              run: |
                  digest="${{ steps.build.outputs.digest }}"
                  mkdir -p "${{ runner.temp }}/digests"
                  touch "${{ runner.temp }}/digests/${digest#sha256:}"
              shell: bash

            - name: Upload digest
              if: github.event_name != 'pull_request'
              uses: actions/upload-artifact@v4
              with:
                  name: digests-${{ matrix.arch }}
                  path: ${{ runner.temp }}/digests/*
                  if-no-files-found: error
                  retention-days: 1

    # Collects the per-architecture digests into a single manifest list and
    # applies the tags to it. Pull requests never push, so there is nothing to
    # merge for them.
    merge:
        runs-on: ubuntu-latest
        needs: build
        if: github.event_name != 'pull_request'
        permissions:
            contents: read
            packages: write

        steps:
            - name: Download digests
              uses: actions/download-artifact@v4
              with:
                  path: ${{ runner.temp }}/digests
                  pattern: digests-*
                  merge-multiple: true

            - name: Set up Buildx
              uses: docker/setup-buildx-action@v3

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

            - name: Extract metadata
              id: meta
              uses: docker/metadata-action@v5
              with:
                  images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
                  # `latest` used to follow the default branch, so every push
                  # to main went straight to the tag the README tells people to
                  # pull — including work in progress, and migrations that run
                  # automatically on boot. It now moves only on a release tag.
                  #
                  # `main` still publishes, under its own name, for anyone who
                  # wants the tip.
                  tags: |
                      type=ref,event=branch
                      type=sha,prefix=sha-
                      type=semver,pattern={{version}}
                      type=semver,pattern={{major}}.{{minor}}
                      type=raw,value=latest,enable=${{ startsWith(github.ref, 'refs/tags/v') }}

            - name: Create manifest list and push
              working-directory: ${{ runner.temp }}/digests
              run: |
                  docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
                    $(printf '${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}@sha256:%s ' *)

            - name: Inspect image
              run: |
                  docker buildx imagetools inspect ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ steps.meta.outputs.version }}