test-dockerfile.yml

name: Build Docker image

on:
  pull_request:
    paths:
    - Dockerfile
    - .github/workflows/test-dockerfile.yml

jobs:
  build:
    name: Build Docker image
    runs-on: ubuntu-latest
    steps:
      -
        name: Checkout
        uses: actions/checkout@v4
      -
        name: Build image
        run: docker build --tag test:latest .
      -
        name: Save image contents
        run: docker save --output /tmp/image.tar test:latest
      -
        name: Extract layer
        run: |
          tar -C /tmp -x -f /tmp/image.tar --strip-components=1
          if [ ! -d /tmp/sha256 ]; then 
            echo 'Cannot extract docker archive.'
            exit 1 
          fi
      -
        name: Check layer contents
        run: |
          ENTRY="$(find /tmp/sha256 -type f -exec tar -vtf {} \; 2>/dev/null | grep install-php-extensions)"
          if [ -z "$ENTRY" ]; then
            echo 'File not found'
            exit 1
          fi
          if ! printf '%s' "$ENTRY" | grep -E '^.r.xr.xr.x '; then
            printf 'Invalid entry permissions:\n%s\n' "$ENTRY"
            exit 1
          fi
          echo 'Entry is correct.'