CI vs CD Explained

# .github/workflows/ci.yml
name: CI Pipeline
on:
  push:
    branches: [main, develop]
  pull_request:
    branches: [main]
 
jobs:
  quality-check:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      
      - name: Setup Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '18'
      
      - name: Install dependencies
        run: npm ci
      
      - name: Run ESLint
        run: npm run lint
        
      - name: Run unit tests
        run: npm test -- --coverage
        
      - name: Check code coverage
        run: |
          COVERAGE=$(npm run coverage:report | grep "Statements:" | awk '{print $NF}' | sed 's/%//')
          if (( $(echo "$COVERAGE < 80" | bc -l) )); then
            echo "Coverage too low: $COVERAGE%"
            exit 1
          fi
          
      - name: Build project
        run: npm run build
        
      - name: Upload coverage to Codecov
        uses: codecov/codecov-action@v3

# .github/workflows/cd.yml
name: Continuous Delivery
on:
  push:
    branches: [main]
    tags: ['v*']
 
jobs:
  build-and-test:
    runs-on: ubuntu-latest
    outputs:
      image-tag: ${{ steps.meta.outputs.tags }}
    steps:
      - uses: actions/checkout@v4
      - name: Setup Node
        uses: actions/setup-node@v4
        with:
          node-version: '18'
      - run: npm ci
      - run: npm run lint
      - run: npm test
      - run: npm run build
      
      - name: Build Docker image
        run: |
          docker build -t myapp:${{ github.sha }} .
          docker build -t myapp:latest .
      
      - name: Push to registry
        run: |
          docker push myapp:${{ github.sha }}
          docker push myapp:latest
 
  deploy-staging:
    needs: build-and-test
    runs-on: ubuntu-latest
    if: github.ref == 'refs/heads/main'
    steps:
      - name: Deploy to Staging
        run: |
          kubectl set image deployment/myapp-staging \
            myapp=myapp:${{ github.sha }} \
            -n staging
      
      - name: Wait for rollout
        run: kubectl rollout status deployment/myapp-staging -n staging
      
      - name: Run integration tests
        run: npm run test:integration -- --url https://staging.myapp.com
      
      - name: Run E2E tests
        run: npm run test:e2e -- --url https://staging.myapp.com
      
      - name: Run performance tests
        run: npm run test:performance -- --url https://staging.myapp.com
 
  manual-approval:
    needs: deploy-staging
    runs-on: ubuntu-latest
    environment:
      name: production
    steps:
      - run: echo "Awaiting GitHub approval..."
 
  deploy-production:
    needs: manual-approval
    runs-on: ubuntu-latest
    steps:
      - name: Deploy to Production
        run: |
          kubectl set image deployment/myapp \
            myapp=myapp:${{ github.sha }} \
            -n production
      
      - name: Monitor deployment
        run: |
          kubectl rollout status deployment/myapp -n production
          
      - name: Health checks
        run: |
          curl -f https://myapp.com/health || exit 1
          
      - name: Create GitHub Release
        run: |
          gh release create v${{ github.sha }} \
            --notes "Production deployment" \
            --draft=false
 
  notify:
    needs: [deploy-staging, deploy-production]
    runs-on: ubuntu-latest
    if: always()
    steps:
      - name: Send Slack notification
        run: |
          curl -X POST ${{ secrets.SLACK_WEBHOOK }} \
            -d '{"text":"Production deployment complete ✅"}'

jobs:
  auto-deploy-production:
    runs-on: ubuntu-latest
    needs: build-and-test
    if: github.ref == 'refs/heads/main' && github.event_name == 'push'
    steps:
      - uses: actions/checkout@v4
      
      - name: Deploy to Production
        run: |
          kubectl set image deployment/myapp \
            myapp=myapp:${{ github.sha }} \
            -n production
      
      - name: Monitor deployment rollout
        run: kubectl rollout status deployment/myapp -n production
      
      - name: Wait 2 minutes for stabilization
        run: sleep 120
      
      - name: Check error rate (CloudWatch)
        run: |
          ERROR_RATE=$(aws cloudwatch get-metric-statistics \
            --namespace AWS/ApplicationELB \
            --metric-name HTTPCode_Target_5XX_Count \
            --start-time $(date -u -d '5 minutes ago' +%Y-%m-%dT%H:%M:%S) \
            --end-time $(date -u +%Y-%m-%dT%H:%M:%S) \
            --period 60 \
            --statistics Sum \
            --query 'Datapoints[0].Sum' \
            --output text)
          
          if [ "$ERROR_RATE" != "None" ] && [ "$ERROR_RATE" -gt 100 ]; then
            echo "Error rate too high: $ERROR_RATE 5XX errors in last 5 min"
            kubectl rollout undo deployment/myapp -n production
            exit 1
          fi
      
      - name: Check latency
        run: |
          LATENCY=$(aws cloudwatch get-metric-statistics \
            --namespace AWS/ApplicationELB \
            --metric-name TargetResponseTime \
            --start-time $(date -u -d '5 minutes ago' +%Y-%m-%dT%H:%M:%S) \
            --end-time $(date -u +%Y-%m-%dT%H:%M:%S) \
            --period 60 \
            --statistics Average \
            --query 'Datapoints[0].Average' \
            --output text)
          
          if (( $(echo "$LATENCY > 2.0" | bc -l) )); then
            echo "Latency too high: ${LATENCY}s (max: 2.0s)"
            kubectl rollout undo deployment/myapp -n production
            exit 1
          fi
      
      - name: Deployment successful
        if: success()
        run: echo "Production deployment successful ✅"
      
      - name: Send Slack notification
        if: always()
        run: |
          STATUS=${{ job.status }}
          curl -X POST ${{ secrets.SLACK_WEBHOOK }} \
            -d "{\"text\":\"Production deployment: $STATUS\"}"

// Code deployed to production but feature is OFF
if (featureFlags.get('new-checkout-v2')) {
  renderNewCheckout();  // Hidden from users
} else {
  renderOldCheckout();  // Active for all users
}