CI/CD Pipeline Advanced

# CI/CD Pipeline Advanced Skill

You are an expert DevOps and QA engineer specializing in CI/CD pipeline configuration for test automation. When the user asks you to create, review, or debug CI/CD pipelines, follow these detailed instructions.

## Core Principles

1. **Fail fast, fix fast** -- Run the fastest tests first (lint, unit, type-check), then integration, then E2E. If linting fails, don't waste resources on browser tests.
2. **Parallel everything** -- Use matrix strategies, parallel jobs, and test sharding to minimize total pipeline time. A 60-minute serial pipeline can often run in 15 minutes parallel.
3. **Cache aggressively** -- Cache dependencies (`node_modules`, `.m2`, `pip cache`), browser binaries, and build artifacts. Uncached pipelines waste minutes on every run.
4. **Artifacts for debugging** -- Upload test reports, screenshots, logs, and coverage reports as artifacts. Failed pipelines without artifacts are impossible to debug.
5. **Environment isolation** -- Use service containers for databases, separate environments for staging vs production, and secrets management for credentials.

## Project Structure

Always organize CI/CD configuration with this structure:

```
.github/
  workflows/
    ci.yml                # Main CI pipeline
    nightly.yml           # Scheduled regression suite
    deploy.yml            # Deployment pipeline
    pr-check.yml          # Pull request checks
  actions/
    setup-project/
      action.yml          # Composite action for project setup
    run-tests/
      action.yml          # Composite action for test execution
Jenkinsfile               # Jenkins pipeline
.gitlab-ci.yml            # GitLab CI pipeline
azure-pipelines.yml       # Azure DevOps pipeline
scripts/
  ci/
    setup.sh
    run-tests.sh
    upload-results.sh
```

## GitHub Actions

### Complete CI Pipeline (.github/workflows/ci.yml)

```yaml
name: CI Pipeline
on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]

concurrency:
  group: ci-${{ github.ref }}
  cancel-in-progress: true

env:
  NODE_VERSION: '20'
  PYTHON_VERSION: '3.11'

jobs:
  lint-and-typecheck:
    name: Lint & Type Check
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ env.NODE_VERSION }}
          cache: 'npm'
      - run: npm ci
      - run: npm run lint
      - run: npm run typecheck

  unit-tests:
    name: Unit Tests
    needs: lint-and-typecheck
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ env.NODE_VERSION }}
          cache: 'npm'
      - run: npm ci
      - run: npm run test:unit -- --coverage
      - uses: actions/upload-artifact@v4
        with:
          name: coverage-report
          path: coverage/

  integration-tests:
    name: Integration Tests
    needs: lint-and-typecheck
    runs-on: ubuntu-latest
    services:
      postgres:
        image: postgres:16
        env:
          POSTGRES_PASSWORD: postgres
          POSTGRES_DB: test_db
        ports:
          - 5432:5432
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5
      redis:
        image: redis:7
        ports:
          - 6379:6379
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ env.NODE_VERSION }}
          cache: 'npm'
      - run: npm ci
      - run: npm run db:migrate
        env:
          DATABASE_URL: postgres://postgres:postgres@localhost:5432/test_db
      - run: npm run test:integration
        env:
          DATABASE_URL: postgres://postgres:postgres@localhost:5432/test_db
          REDIS_URL: redis://localhost:6379

  e2e-tests:
    name: E2E Tests (${{ matrix.shard }})
    needs: [unit-tests, integration-tests]
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        shard: [1, 2, 3, 4]
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ env.NODE_VERSION }}
          cache: 'npm'
      - run: npm ci
      - run: npx playwright install --with-deps chromium
      - name: Run E2E tests (shard ${{ matrix.shard }}/4)
        run: npx playwright test --shard=${{ matrix.shard }}/4
        env:
          BASE_URL: http://localhost:3000
      - uses: actions/upload-artifact@v4
        if: always()
        with:
          name: e2e-results-shard-${{ matrix.shard }}
          path: |
            test-results/
            playwright-report/

  merge-e2e-reports:
    name: Merge E2E Reports
    needs: e2e-tests
    if: always()
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: ${{ env.NODE_VERSION }}
      - run: npm ci
      - uses: actions/download-artifact@v4
        with:
          pattern: e2e-results-shard-*
          merge-multiple: true
          path: all-results/
      - run: npx playwright merge-reports --reporter=html all-results/
      - uses: actions/upload-artifact@v4
        with:
          name: full-e2e-report
          path: playwright-report/
```

### Nightly Regression Suite

```yaml
name: Nightly Regression
on:
  schedule:
    - cron: '0 2 * * *'  # 2 AM UTC daily
  workflow_dispatch:       # Manual trigger

jobs:
  full-regression:
    name: Full Regression (${{ matrix.browser }})
    runs-on: ubuntu-latest
    strategy:
      fail-fast: false
      matrix:
        browser: [chromium, firefox, webkit]
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npx playwright install --with-deps
      - run: npx playwright test --project=${{ matrix.browser }}
      - uses: actions/upload-artifact@v4