pr-build.yml

name: PR-Build

run-name: PR Build Image

on:
  pull_request:
    branches: ['main']
    
jobs:
  pr-build:
    # https://github.com/actions/runner-images
    runs-on: ubuntu-latest

    steps:

      # debug
      - run: echo "🎉 The job was automatically triggered by a ${{ github.event_name }} event from ${{ github.actor }}."
      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by GitHub!"
      - run: echo "🔎 The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."

      # checkout
      - name: Check out repository code
        uses: actions/checkout@v4
        with:
          fetch-depth: 0 # all history for tags and branches, needed to resolve tag->branch name

      # https://docs.docker.com/build/ci/github-actions/multi-platform/
      # QEMU for software emulation of multiple platforms
      - name: Set up QEMU
        uses: docker/setup-qemu-action@v3
      # Docker buildx/buildkit for multi-platform builds
      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@v3

      # debug
      - run: echo "💡 The ${{ github.repository }} repository has been cloned to the runner."
      - run: echo "🖥️ The workflow is now ready to test your code on the runner."
      - name: List files in the repository
        run: |
          ls ${{ github.workspace }}
      - run: echo "🍏 This job's status is ${{ job.status }}."

      # debug github context and env
      - name: Dump env
        run: env | sort
      - name: Dump GitHub context
        env:
          GITHUB_CONTEXT: ${{ toJson(github) }}
        run: echo "$GITHUB_CONTEXT"

      # - name: calculate branch name IF branch
      #   if: github.ref_type == 'branch' # 'branch' if regular push
      #   run: |
      #     echo "GITHUB_REF_NAME = $GITHUB_REF_NAME"
      #     echo "GITHUB_SHA = ${{ github.event.pull_request.head.sha }}"
      #     short_sha=`git rev-parse --short ${{ github.event.pull_request.head.sha }}`
      #     echo "short SHA = $short_sha"
      #     echo candidates for branch name
      #     git for-each-ref | grep ^$short_sha | grep origin | grep -v HEAD
      #     branch_name=`git for-each-ref | grep ^$short_sha | grep origin | grep -v HEAD | head -n1 | sed "s/.*\///"`
      #     echo tag $GITHUB_REF_NAME is on branch $branch_name

      - name: calculate branch name IF branch
        if: github.ref_type == 'branch' # 'branch' if regular push
        run: |
          echo "GITHUB_REF_NAME = $GITHUB_REF_NAME"
          echo "GITHUB_SHA = ${{ github.event.pull_request.head.sha }}"
          short_sha=`git rev-parse --short ${{ github.event.pull_request.head.sha }}`
          echo "short SHA = $short_sha"
          echo candidates for branch name
          git for-each-ref | grep ^$short_sha | grep origin | grep -v HEAD
          branch_name=`git for-each-ref | grep ^$short_sha | grep origin | grep -v HEAD | head -n1 | sed "s/.*\///"`
          echo tag $GITHUB_REF_NAME is on branch $branch_name

      # tags and labels
      - name: Extract metadata (tags, labels) for image ${{ env.FULL_IMAGE_NAME }}
        id: meta
        uses: docker/metadata-action@v4
        with:
          # https://docs.github.com/en/actions/publishing-packages/publishing-docker-images
          images: |
            ${{ env.GH_REGISTRY }}/${{ env.FULL_IMAGE_NAME }}
          tags: |
            type=semver,pattern={{version}}
            type=ref,event=pr
            type=ref,event=branch
            # in addition to full semantic version (x.y.z) would also create (x.y)
            #type=semver,pattern={{major}}.{{minor}}

      - name: Get fresh build arguments
        shell: bash
        run: echo -e "BUILD_TIME=$(date -u '+%Y-%m-%d_%H:%M:%S')\nGITREF=$(git rev-parse --short HEAD)" >> $GITHUB_OUTPUT
        id: get_buildargs

      - name: Build PR Image
        uses: docker/build-push-action@v5
        with:
          context: .
          push: false
          platforms: linux/amd64,linux/arm64,linux/arm/v7
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          build-args: |
            MY_VERSION=${{ fromJSON(steps.meta.outputs.json).labels['org.opencontainers.image.version'] }}
            MY_BUILTBY=github-action
            BUILD_TIME=${{ steps.get_buildargs.outputs.BUILD_TIME }}
            GITREF=${{ steps.get_buildargs.outputs.GITREF }}
            GITREF_long="${{ github.sha }}"