CI/CD Pipeline Design

## The Purpose of CI/CD Continuous Integration (CI) ensures that every code change is automatically built, tested, and validated. Continuous Deployment (CD) extends this by automatically releasing validated changes to production. Together, CI/CD pipelines reduce manual errors, speed up delivery, and increase developer confidence. A well-designed pipeline acts as a quality gate. It catches issues early, enforces standards, and provides fast feedback so developers can iterate quickly. ## Pipeline Stages A typical CI/CD pipeline has four stages: build, test, artifact, and deploy. Each stage validates a different aspect of the codebase. ```yaml # .github/workflows/ci.yml name: CI/CD Pipeline on: push: branches: [main, develop] pull_request: branches: [main] jobs: build: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 cache: "pnpm" - run: pnpm install --frozen-lockfile - run: pnpm build test: needs: build runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 cache: "pnpm" - run: pnpm install --frozen-lockfile - run: pnpm lint - run: pnpm typecheck - run: pnpm test --coverage - run: pnpm test:e2e ``` ## Linting and Type Checking Static analysis runs before tests to catch formatting and type errors early. This prevents style debates in code reviews and catches bugs at compile time. ```yaml lint: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 cache: "pnpm" - run: pnpm install --frozen-lockfile - run: pnpm lint:api - run: pnpm lint:web - run: pnpm typecheck:api - run: pnpm typecheck:web ``` ## Running Tests Effectively Test strategy should be layered. Unit tests run fast and provide broad coverage. Integration tests verify component interactions. End-to-end tests validate critical user journeys. ```yaml unit-tests: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 cache: "pnpm" - run: pnpm install --frozen-lockfile - run: pnpm test:api - run: pnpm test:web e2e-tests: needs: build runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 cache: "pnpm" - run: pnpm install --frozen-lockfile - run: pnpm test:e2e ``` Run tests in parallel where possible to reduce pipeline duration. Cache dependencies between runs and avoid re-running unchanged test suites. ## Deployment Strategies ### Blue-Green Deployment Maintain two identical environments. Route traffic to the new version after validation, with instant rollback by switching back. ### Canary Deployment Gradually route a percentage of traffic to the new version. Monitor error rates and performance before promoting to full rollout. ### Rolling Deployment Replace instances incrementally across the fleet. Balances resource usage with deployment speed. ```yaml deploy-staging: needs: [lint, unit-tests, e2e-tests] runs-on: ubuntu-latest if: github.ref == 'refs/heads/develop' environment: staging steps: - uses: actions/checkout@v4 - run: pnpm install --frozen-lockfile - run: pnpm build - run: pnpm deploy:staging deploy-production: needs: deploy-staging runs-on: ubuntu-latest if: github.ref == 'refs/heads/main' environment: production steps: - uses: actions/checkout@v4 - run: pnpm install --frozen-lockfile - run: pnpm build - run: pnpm deploy:production ``` ## Environment Management Separate environments for development, staging, and production prevent untested changes from reaching users. Each environment has its own secrets, databases, and configuration. - **Development**: Local and feature branch deployments for iteration - **Staging**: Mirrors production for final validation before release - **Production**: The live environment serving real users Use environment protection rules to require approvals before production deployments. ## Secret Management Never hardcode secrets in pipeline files. Use your platform's secret management features to inject sensitive values at runtime. ```yaml deploy: runs-on: ubuntu-latest environment: production steps: - run: | echo "Deploying with database URL from environment secrets" pnpm deploy:production env: DATABASE_URL: ${{ secrets.DATABASE_URL }} REDIS_URL: ${{ secrets.REDIS_URL }} API_KEY: ${{ secrets.API_KEY }} ``` ## Performance Optimization - **Cache dependencies** between pipeline runs using built-in cache actions - **Run independent jobs in parallel** to reduce total pipeline time - **Skip unchanged stages** using path filters or change detection - **Use matrix strategies** to test across multiple versions or platforms simultaneously - **Set timeouts** on jobs to prevent stuck pipelines from consuming resources ## Monitoring and Rollback After deployment, monitor error rates, latency, and key business metrics. If anomalies are detected, roll back automatically or manually. ```yaml post-deploy: needs: deploy-production runs-on: ubuntu-latest steps: - run: | sleep 60 curl -f https://api.example.com/health || exit 1 - run: | ERROR_RATE=$(curl -s https://api.example.com/metrics/error-rate) if (( $(echo "$ERROR_RATE > 0.05" | bc -l) )); then echo "Error rate exceeds threshold, triggering rollback" pnpm deploy:rollback fi ```