development-image-build.yml

name: Docker Build images during PR development

on:
  pull_request:
    branches:
      - develop  
    paths:
        - 'root_orchestrator/**/Dockerfile'
        - 'root_orchestrator/**/requirements.txt'
        - 'cluster_orchestrator/**/Dockerfile'
        - 'cluster_orchestrator/**/requirements.txt'

jobs:
  gather-modified-files:
    runs-on: ubuntu-latest
    outputs:
      matrix: ${{ steps.folders.outputs.value }}
    steps:
      - name: Run
        uses: actions/checkout@v3

      - name: Get all matching changed files
        id: changed-files
        uses: tj-actions/changed-files@v44
        with:
          since_last_remote_commit: true 
          files: |
            ./**/**/Dockerfile
            ./**/**/requirements.txt
      - name: Run step if matching changed files are detected
        id: folders
        if: steps.changed-files.outputs.any_changed == 'true'  
        env:
                DETECTED_CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
        run: |
                # Extract parent directory of each changed file
                echo "Changed file detected: $DETECTED_CHANGED_FILES"
                # Split the string delimited by a space into an array
                readarray -d ' ' -t context_array <<< "$DETECTED_CHANGED_FILES"
                
                # Declare an empty array to store the results
                value=()
                
                # Loop through each element in the context_array
                for element in "${context_array[@]}"; do
                # Apply dirname function to each element and store the result in the value array
                value+=("$(dirname "$element")")
                done
                
                # Format the output string
                output="value=["
                for item in "${value[@]}"; do
                output+="\"$item\", "
                done
                
                # Remove the trailing comma and add closing bracket and quotes
                output="${output%, }]"
                
                # Print the formatted output string
                echo "$output" >> $GITHUB_OUTPUT
                  
### Dynamic matrix for spawning multiple build jobs
  build:
    needs: [ gather-modified-files ]
    runs-on: ubuntu-latest
    env:
        # Use docker.io for Docker Hub if empty
        REGISTRY: ghcr.io
        # github.repository as <account>/<repo>
        IMAGE_NAME: ${{ github.repository }}/${{ matrix.value }}
    permissions:
        contents: read
        packages: write
        id-token: write
    strategy:
      matrix:
        value: ${{fromJSON(needs.gather-modified-files.outputs.matrix)}}
    steps:      
      - name: Checkout repository
        uses: actions/checkout@v3

      - name: Set up Docker Buildx
        uses: docker/setup-buildx-action@79abd3f86f79a9d68a23c75a09a9a85889262adf

      - name: Extract Docker metadata
        id: meta
        uses: docker/metadata-action@v3
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          flavor: |
            latest=${{!startsWith(github.ref, 'refs/tags/alpha')}}
  
      - name: Set up QEMU
        id: qemu
        uses: docker/setup-qemu-action@v1
        with:
            image: tonistiigi/binfmt:latest
            platforms: all
    
    # Build Docker image with Buildx (matching file push on same PR)
      - name: Build Docker image (push disabled)
        env:
            DOCKERFILE_CONTEXT: ${{ matrix.value }}
        id: build-and-push
        uses: docker/build-push-action@v3
        with:
            context: |
                ${{format('./{0}/', matrix.value)}}
            # To build on all supported arch, add to following line: ,linux/armhf,linux/arm64
            platforms: linux/amd64
            push: false
            tags: ${{ steps.meta.outputs.tags }}
            labels: ${{ steps.meta.outputs.labels }}