CI/CD з GitHub Actions: тести, збірка образу й деплой

pull request ──► lint + тести ──► (зелено) ──► можна мерджити
push у main ──► тести ──► збірка образу ──► push у реєстр ──► деплой на staging
тег v* ──► деплой у production (з підтвердженням)

# .github/workflows/ci.yml
name: ci
on:
  pull_request:
  push:
    branches: [main]

concurrency:
  group: ci-${{ github.ref }}
  cancel-in-progress: true   # новий push скасовує застарілий прогін

permissions:
  contents: read

jobs:
  test:
    runs-on: ubuntu-latest
    services:
      postgres:
        image: postgres:17-alpine
        env:
          POSTGRES_PASSWORD: test
        ports: ["5432:5432"]
        options: >-
          --health-cmd "pg_isready -U postgres"
          --health-interval 5s --health-retries 10
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-python@v5
        with:
          python-version: "3.13"
          cache: pip
      - run: pip install -r requirements.txt -r requirements-dev.txt
      - run: ruff check .
      - run: pytest -q --maxfail=1
        env:
          DATABASE_URL: postgres://postgres:test@localhost:5432/postgres

  image:
    needs: test
    if: github.event_name == 'push' && github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write          # публікація в GitHub Container Registry
    outputs:
      tag: ${{ steps.meta.outputs.version }}
    steps:
      - uses: actions/checkout@v4
      - uses: docker/setup-buildx-action@v3
      - uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}
      - id: meta
        uses: docker/metadata-action@v5
        with:
          images: ghcr.io/${{ github.repository }}
          tags: type=sha,format=short
      - uses: docker/build-push-action@v6
        with:
          push: true
          tags: ${{ steps.meta.outputs.tags }}
          cache-from: type=gha
          cache-to: type=gha,mode=max

  deploy-staging:
    needs: image
    runs-on: ubuntu-latest
    environment: staging
    steps:
      - name: Deploy
        run: |
          curl -fsS -X POST "$DEPLOY_HOOK" \
            -H "Authorization: Bearer $DEPLOY_TOKEN" \
            -d "image=ghcr.io/${{ github.repository }}:${{ needs.image.outputs.tag }}"
        env:
          DEPLOY_HOOK: ${{ vars.DEPLOY_HOOK }}
          DEPLOY_TOKEN: ${{ secrets.DEPLOY_TOKEN }}

  deploy-production:
    needs: [image, deploy-staging]
    runs-on: ubuntu-latest
    environment: production     # тут налаштовано обов'язкове підтвердження
    steps:
      - run: echo "Деплой ${{ needs.image.outputs.tag }} у production"