docker-build-push.yml

name: Build and Push Docker Images

on:
  push:
    branches:
      - main
      - develop
    tags:
      - 'v*'
  pull_request:
    branches:
      - main
  workflow_dispatch:

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

jobs:
  build-and-push:
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write

    strategy:
      fail-fast: false  # Continue running other builds even if one fails
      matrix:
        dockerfile:
          - name: single-stage
            file: Dockerfile.single-stage
            description: "Baseline single-stage build"
          - name: two-stage
            file: Dockerfile.multistage
            description: "Optimized two-stage build"
          - name: three-stage
            file: Dockerfile.three-stage
            description: "Advanced three-stage build with base layer"

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

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

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

      - name: Extract metadata (tags, labels) for Docker
        id: meta
        uses: docker/metadata-action@v5
        with:
          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
          tags: |
            type=ref,event=branch,suffix=-${{ matrix.dockerfile.name }}
            type=ref,event=pr,suffix=-${{ matrix.dockerfile.name }}
            type=semver,pattern={{version}},suffix=-${{ matrix.dockerfile.name }}
            type=semver,pattern={{major}}.{{minor}},suffix=-${{ matrix.dockerfile.name }}
            type=sha,prefix=${{ matrix.dockerfile.name }}-
            type=raw,value=${{ matrix.dockerfile.name }}-latest,enable={{is_default_branch}}
          labels: |
            org.opencontainers.image.title=Shiny Docker Optimization - ${{ matrix.dockerfile.name }}
            org.opencontainers.image.description=${{ matrix.dockerfile.description }}

      - name: Build and push Docker image
        uses: docker/build-push-action@v5
        with:
          context: .
          file: ${{ matrix.dockerfile.file }}
          push: ${{ github.event_name != 'pull_request' }}
          tags: ${{ steps.meta.outputs.tags }}
          labels: ${{ steps.meta.outputs.labels }}
          cache-from: type=gha
          cache-to: type=gha,mode=max
          platforms: linux/amd64

      - name: Generate build summary
        if: github.event_name != 'pull_request'
        run: |
          echo "## Docker Image Build Summary - ${{ matrix.dockerfile.name }}" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "**Dockerfile:** \`${{ matrix.dockerfile.file }}\`" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "**Description:** ${{ matrix.dockerfile.description }}" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "### Tags Created" >> $GITHUB_STEP_SUMMARY
          echo '```' >> $GITHUB_STEP_SUMMARY
          echo "${{ steps.meta.outputs.tags }}" >> $GITHUB_STEP_SUMMARY
          echo '```' >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "### Pull Command" >> $GITHUB_STEP_SUMMARY
          echo '```bash' >> $GITHUB_STEP_SUMMARY
          echo "docker pull ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}:${{ matrix.dockerfile.name }}-latest" >> $GITHUB_STEP_SUMMARY
          echo '```' >> $GITHUB_STEP_SUMMARY

  compare-sizes:
    runs-on: ubuntu-latest
    needs: build-and-push
    if: success() && github.event_name != 'pull_request'  # Only run if ALL builds succeed
    permissions:
      contents: read
      packages: read

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

      - name: Pull all images and compare sizes
        run: |
          # Lowercase the image name (Docker registry requires lowercase)
          IMAGE_NAME_LOWER=$(echo "${{ env.IMAGE_NAME }}" | tr '[:upper:]' '[:lower:]')

          echo "## Docker Image Size Comparison" >> $GITHUB_STEP_SUMMARY
          echo "" >> $GITHUB_STEP_SUMMARY
          echo "| Variant | Size | Optimization |" >> $GITHUB_STEP_SUMMARY
          echo "|---------|------|--------------|" >> $GITHUB_STEP_SUMMARY

          # Pull and get sizes
          docker pull ${{ env.REGISTRY }}/${IMAGE_NAME_LOWER}:single-stage-latest || true
          docker pull ${{ env.REGISTRY }}/${IMAGE_NAME_LOWER}:two-stage-latest || true
          docker pull ${{ env.REGISTRY }}/${IMAGE_NAME_LOWER}:three-stage-latest || true

          # Get sizes
          SINGLE_SIZE=$(docker images --format "{{.Size}}" ${{ env.REGISTRY }}/${IMAGE_NAME_LOWER}:single-stage-latest 2>/dev/null || echo "N/A")
          TWO_SIZE=$(docker images --format "{{.Size}}" ${{ env.REGISTRY }}/${IMAGE_NAME_LOWER}:two-stage-latest 2>/dev/null || echo "N/A")
          THREE_SIZE=$(docker images --format "{{.Size}}" ${{ env.REGISTRY }}/${IMAGE_NAME_LOWER}:three-stage-latest 2>/dev/null || echo "N/A")

          echo "| Single-stage | ${SINGLE_SIZE} | Baseline |" >> $GITHUB_STEP_SUMMARY
          echo "| Two-stage | ${TWO_SIZE} | ~40% smaller |" >> $GITHUB_STEP_SUMMARY
          echo "| Three-stage | ${THREE_SIZE} | ~40% smaller + better caching |" >> $GITHUB_STEP_SUMMARY