CI/CD and Automation

Automate quality gates so that no change reaches production without passing tests, lint, type checking, and build.

When to Use

• Setting up a new project's CI pipeline
• Adding or modifying automated checks
• Configuring deployment pipelines
• When a change should trigger automated verification
• Debugging CI failures

Core Principles

Shift Left: Catch problems as early in the pipeline as possible. A bug caught in linting costs minutes; the same bug caught in production costs hours.

Faster is Safer: Smaller batches and more frequent releases reduce risk, not increase it. A deployment with 3 changes is easier to debug than one with 30.

The Quality Gate Pipeline

Every change goes through these gates before merge:

Pull Request Opened
    │
    ▼
┌─────────────────┐
│   LINT CHECK     │  eslint, prettier
│   ↓ pass         │
│   TYPE CHECK     │  tsc --noEmit
│   ↓ pass         │
│   UNIT TESTS     │  jest/vitest
│   ↓ pass         │
│   BUILD          │  npm run build
│   ↓ pass         │
│   INTEGRATION    │  API/DB tests
│   ↓ pass         │
│   E2E (optional) │  Playwright/Cypress
│   ↓ pass         │
│   SECURITY AUDIT │  npm audit
│   ↓ pass         │
│   BUNDLE SIZE    │  bundlesize check
└─────────────────┘
    │
    ▼
  Ready for review

No gate can be skipped. If lint fails, fix lint — don't disable the rule.

GitHub Actions Configuration

Basic CI Pipeline

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

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

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

      - uses: actions/setup-node@v4
        with:
          node-version: '22'
          cache: 'npm'

      - name: Install dependencies
        run: npm ci

      - name: Lint
        run: npm run lint

      - name: Type check
        run: npx tsc --noEmit

      - name: Test
        run: npm test -- --coverage

      - name: Build
        run: npm run build

      - name: Security audit
        run: npm audit --audit-level=high

With Database Integration Tests

  integration:
    runs-on: ubuntu-latest
    services:
      postgres:
        image: postgres:16
        env:
          POSTGRES_DB: testdb
          POSTGRES_USER: ci_user
          POSTGRES_PASSWORD: ${{ secrets.CI_DB_PASSWORD }}
        ports:
          - 5432:5432
        options: >-
          --health-cmd pg_isready
          --health-interval 10s
          --health-timeout 5s
          --health-retries 5

    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '22'
          cache: 'npm'
      - run: npm ci
      - name: Run migrations
        run: npx prisma migrate deploy
        env:
          DATABASE_URL: postgresql://ci_user:${{ secrets.CI_DB_PASSWORD }}@localhost:5432/testdb
      - name: Integration tests
        run: npm run test:integration
        env:
          DATABASE_URL: postgresql://ci_user:${{ secrets.CI_DB_PASSWORD }}@localhost:5432/testdb

E2E Tests

  e2e:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: actions/setup-node@v4
        with:
          node-version: '22'
          cache: 'npm'
      - run: npm ci
      - name: Install Playwright
        run: npx playwright install --with-deps chromium
      - name: Build
        run: npm run build
      - name: Run E2E tests
        run: npx playwright test
      - uses: actions/upload-artifact@v4
        if: failure()
        with:
          name: playwright-report
          path: playwright-report/

Feeding CI Failures Back to Agents

When CI fails:

CI fails
    │
    ▼
Copy the failure output
    │
    ▼
Feed it to the agent:
"The CI pipeline failed with this error:
[paste specific error]
Fix the issue and verify locally before pushing again."
    │
    ▼
Agent fixes → pushes → CI runs again

Deployment Strategies

Preview Deployments

Every PR gets a preview deployment for manual testing:

deploy-preview:
  runs-on: ubuntu-latest
  if: github.event_name == 'pull_request'
  steps:
    - uses: actions/checkout@v4
    - name: Deploy preview
      run: npx vercel --token=${{ secrets.VERCEL_TOKEN }}

Feature Flags

Feature flags decouple deployment from release:

• Ship code without enabling it. Merge to main early, enable when ready.
• Roll back without redeploying. Disable the flag instead of reverting code.
• Canary new features. Enable for 1% of users, then 10%, then 100%.

// Simple feature flag pattern
if (featureFlags.isEnabled('new-checkout-flow', { userId })) {
  return renderNewCheckout();
}
return renderLegacyCheckout();

Staged Rollouts

PR merged to main
    │
    ▼
  Staging deployment (auto)
    │ Manual verification
    ▼
  Production deployment (manual trigger)
    │
    ▼
  Monitor for errors (15-minute window)
    │
    ├── Errors detected → Rollback
    └── Clean → Done

CI Optimization

When the pipeline exceeds 10 minutes:

Slow CI pipeline?
├── Cache dependencies
│   └── Use actions/cache or setup-node cache option
├── Run jobs in parallel
│   └── Split lint, typecheck, test, build into separate jobs
├── Only run what changed
│   └── Use path filters to skip unrelated jobs
├── Use matrix builds
│   └── Shard test suites across multiple runners
└── Optimize the test suite
    └── Remove slow tests from the critical path

Verification

After setting up or modifying CI:

• All quality gates are present (lint, types, tests, build, audit)
• Pipeline runs on every PR and push to main
• Failures block merge (branch protection configured)
• CI results feed back into the development loop
• Secrets are stored in the secrets manager, not in code
• Deployment has a rollback mechanism
• Pipeline runs in under 10 minutes for the test suite