push-mimir-build-image.yml

name: Build and Push mimir-build-image

# configure trigger by pull request
on:
  pull_request:
    types: [opened, synchronize]
    paths:
      - mimir-build-image/Dockerfile  

concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs: 
  build_and_push:
    runs-on: ubuntu-latest
    permissions:
      # Allow pushing to the GitHub repo for collaborators, forks should remain read-only
      contents: write
      # Allow PR modification for collaborators, forks should remain read-only
      pull-requests: write
    steps:
      - name: Checkout Repository
        uses: actions/checkout@v4

      - name: Checkout Pull Request Branch
        run: gh pr checkout ${{ github.event.pull_request.number }}
        env:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}

      - name: Setup QEMU
        uses: docker/setup-qemu-action@v3

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

      - name: Login to Docker Hub
        uses: docker/login-action@v3
        with:
          username: ${{ secrets.DOCKER_USERNAME }}
          password: ${{ secrets.DOCKER_PASSWORD }}

      - name: Prepare Variables
        id: prepare
        run: |
          echo "path=mimir-build-image/Dockerfile" >> $GITHUB_OUTPUT
          main_build_image=$(make print-build-image)
          main_image_tag=$(echo $main_build_image | cut -d ':' -f 2)
          image_name=$(echo $main_build_image | cut -d ':' -f 1)
          echo "image=$image_name" >> $GITHUB_OUTPUT
          echo "main_image_tag=$main_image_tag" >> $GITHUB_OUTPUT

      - name: Compute Image Tag
        id: compute_hash
        run: |
          current_hash=$(md5sum ${{ steps.prepare.outputs.path }} | awk '{print substr($1, 0, 10)}')
          echo "the file path is ${{ steps.prepare.outputs.path }}"
          echo "build tag is $current_hash"
          tag="pr${{ github.event.pull_request.number }}-$current_hash"
          echo "tag=$tag" >> $GITHUB_OUTPUT

      - name: Check Should Build Image
        id: check_build
        run: |
          echo "Checking if image should be built"
          if skopeo inspect --raw "docker://${{ steps.prepare.outputs.image }}:${{ steps.compute_hash.outputs.tag }}" >/dev/null 2>&1; then
            echo "build=false" >> $GITHUB_OUTPUT
            echo "Tag ${{ steps.compute_hash.outputs.tag }} exists"
          else
            echo "Tag ${{ steps.compute_hash.outputs.tag }} does not exist"
            echo "build=true" >> $GITHUB_OUTPUT
          fi

      - name: Add Comment to the PR
        id: notification
        run: | 
          if [ ${{ steps.check_build.outputs.build }} == 'true' ]; then
           gh pr comment $PR_NUMBER --body "**Building new version of mimir-build-image**. After image is built and pushed to Docker Hub, \
           a new commit will automatically be added to this PR with new image version \\\`$IMAGE:$TAG\\\`. This can take up to 1 hour."
          else
            echo "This PR will not trigger a build of mimir-build-image"
            gh pr comment $PR_NUMBER --body "**Not building new version of mimir-build-image**. This PR modifies \\\`mimir-build-image/Dockerfile\\\`, but the image \\\`$IMAGE:$TAG\\\` already exists."
          fi
        env:
          PR_NUMBER: ${{ github.event.pull_request.number }}
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
          TAG: ${{ steps.compute_hash.outputs.tag }}
          IMAGE: ${{ steps.prepare.outputs.image }}

      - name: Build and Push Docker Image
        if: steps.check_build.outputs.build == 'true'
        run: |
          echo "Building and Pushing Docker Image"
          make push-multiarch-build-image IMAGE_TAG=${{ steps.compute_hash.outputs.tag }}
      
      - name: Compare built tag with Makefile
        id: compare_tag
        run: |
          echo "Comparing built tag with Makefile"
          if [ ${{ steps.compute_hash.outputs.tag }} == "$(make print-build-image)" ]; then
            echo "Built tag is the same as the one in Makefile"
            echo "isDifferent=false" >> $GITHUB_OUTPUT
          else
            echo "Built tag is different from the one in Makefile"
            echo "isDifferent=true" >> $GITHUB_OUTPUT
          fi
      
      - name: Add commit to PR in order to update Build Image version
        if: steps.compare_tag.outputs.isDifferent == 'true'
        run: |
          echo "Get current Build Image Version"
          echo "Current Build Image Version is $MAIN_TAG"
          echo "Built Image Version is $TAG"
          if [ "$MAIN_TAG" = "$TAG" ]; then
            echo "Build Image Version is already up to date"
          else
            echo "Build Image Version is not up to date"
            sed -i "s/$MAIN_TAG/${{ steps.compute_hash.outputs.tag }}/g" Makefile
            git config --global user.email "${{ github.event.pull_request.user.login }}@users.noreply.github.com"
            git config --global user.name "${{ github.event.pull_request.user.login }}"
            git add Makefile
            git commit -m "Update build image version to ${{ steps.compute_hash.outputs.tag }}"
            git push origin HEAD
          fi 
        env:
          GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
          TAG: ${{ steps.compute_hash.outputs.tag }}
          MAIN_TAG: ${{ steps.prepare.outputs.main_image_tag }}