name: Dockerfile

# Relevant to events - https://help.github.com/en/actions/automating-your-workflow-with-github-actions/events-that-trigger-workflows
on: 
  pull_request:
    types: [synchronize, opened, reopened, ready_for_review]
    paths:
    - '**.Dockerfile'

jobs:
  # Linting
  lint:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - name: Installing dependencies..
        run: |
          # Fix untill hadolint it available by downstream
          if ! apt-cache search hadolint | grep -qP "^hadolint -"; then
            # Install hadolint if not already installed through apt
            if ! apt list --installed | grep -qP "^hadolint -"; then
              if ! apt-cache search hadolint | grep -qP "^hadolint -.*"; then { if command -v wget >/dev/null; then apt install -y wget; fi ;} && wget https://github.com/hadolint/hadolint/releases/download/v1.17.5/hadolint-Linux-x86_64 -O /usr/bin/hadolint && { [ ! -x hadolint ] && chmod +x /usr/bin/hadolint ;}; elif apt-cache search hadolint | grep -qP "^hadolint -.*"; then apt install -y hadolint; fi
            fi
          fi
      - name: Linting..
        run: |
          cd "$GITHUB_WORKSPACE" && for file in $(git ls-tree --name-only -r ${{ github.sha }} | grep '\.Dockerfile$'); do
            printf 'checking dockerfile %s using hadolint\n' "$file"
            hadolint "$file"
          done