What Is CI/CD and Why Should You Care?
CI (Continuous Integration): Every code push is automatically tested.
CD (Continuous Deployment): Every passing test automatically deploys to production.
Together, they eliminate the "deploy day" stress and catch bugs before users see them.
A Simple CI/CD Pipeline
Code Push → Run Tests → Build → Deploy → Monitor
Setting Up with GitHub Actions
name: CI/CD Pipeline
on:
push:
branches: [main]
pull_request:
branches: [main]
jobs:
test:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- uses: actions/setup-node@v4
- run: npm ci
- run: npm test
- run: npm run lint
deploy:
needs: test
if: github.ref == 'refs/heads/main'
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v4
- run: npm ci && npm run build
# Deploy step here
Testing Strategy for CI
1. Unit tests - test individual functions
2. Integration tests - test API endpoints
3. E2E tests - test user flows (Cypress/Playwright)
4. Linting - catch code style issues
5. Type checking - TypeScript compilation
Deployment Strategies
Rolling deployment: Replace instances one at a time
Blue-green: Run two environments, switch traffic
Canary: Deploy to 5% of users first, then roll out
Key Metrics to Track
- Deployment frequency - how often you ship
- Lead time - code commit to production
- Failure rate - % of deployments that fail
- Recovery time - how fast you fix failures
The best teams deploy multiple times a day. CI/CD makes that possible.
