github-actions-patterns

Skill: GitHub Actions Patterns

Expertise: Reusable workflows, composite actions, OIDC cloud auth, build caching, deployment gates, self-hosted runners.

When to load

When creating or reviewing GitHub Actions workflows for CI, CD, or infrastructure automation.

Standard CI Workflow

# .github/workflows/ci.yml
name: CI

on:
  push:
    branches: [main]
  pull_request:
    branches: [main]

concurrency:
  group: ${{ github.workflow }}-${{ github.ref }}
  cancel-in-progress: true   # cancel outdated runs on new push

jobs:
  validate:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4

      - name: Set up Python
        uses: actions/setup-python@v5
        with:
          python-version: "3.12"
          cache: pip               # built-in pip caching

      - name: Install deps
        run: pip install -r requirements.txt -r requirements-dev.txt

      - name: Lint
        run: ruff check src/ tests/

      - name: Type check
        run: mypy src/ --strict

      - name: Test with coverage
        run: |
          pytest tests/ \
            --cov=src \
            --cov-report=xml \
            --cov-fail-under=80

      - name: Upload coverage
        uses: codecov/codecov-action@v4
        with:
          files: coverage.xml

  build:
    needs: validate
    runs-on: ubuntu-latest
    permissions:
      contents: read
      packages: write
      id-token: write            # for OIDC
    outputs:
      image-digest: ${{ steps.build.outputs.digest }}
    steps:
      - uses: actions/checkout@v4

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

      - name: Login to registry (OIDC — no long-lived secret)
        uses: docker/login-action@v3
        with:
          registry: ghcr.io
          username: ${{ github.actor }}
          password: ${{ secrets.GITHUB_TOKEN }}

      - name: Build and push
        id: build
        uses: docker/build-push-action@v6
        with:
          context: .
          push: ${{ github.event_name == 'push' }}
          tags: ghcr.io/${{ github.repository }}:${{ github.sha }}
          cache-from: type=gha
          cache-to: type=gha,mode=max
          provenance: true         # SLSA provenance attestation
          sbom: true               # generate SBOM

  security-scan:
    needs: build
    runs-on: ubuntu-latest
    steps:
      - name: Scan image for CVEs
        uses: aquasecurity/trivy-action@master
        with:
          image-ref: ghcr.io/${{ github.repository }}:${{ github.sha }}
          format: sarif
          output: trivy-results.sarif
          severity: CRITICAL,HIGH
          exit-code: 1            # fail pipeline on Critical/High

      - name: Upload SARIF to Security tab
        uses: github/codeql-action/upload-sarif@v3
        with:
          sarif_file: trivy-results.sarif