What Is CI/CD? Continuous Integration and Deployment Guide

You wrote code, tested it, uploaded it to the server — and something broke at 3 AM. Manual deployment is the riskiest and most time-consuming process in software development. CI/CD automates and secures this process.

What Is CI/CD?

CI (Continuous Integration)

Automatically testing every code change and merging it with the main branch.

CD (Continuous Delivery)

Automatically preparing tested code for deployment to the production environment.

CD (Continuous Deployment)

Automatically deploying tested code to production — without human intervention.

Why CI/CD?

| Manual Process | With CI/CD | |---------------|-----------| | Deployment takes hours | Minutes | | High error risk | Low with automated tests | | "Works on my machine" | Standardized environment | | Rollback is hard | One-click rollback | | Deployment is scary | Routine and safe | | 1 release per week | Multiple per day |

CI/CD Pipeline Steps

1. Source

• Developer pushes code
• Opens a pull request
• Pipeline starts automatically

2. Build

• Code is compiled
• Dependencies installed
• Docker image created

3. Test

• Unit tests run
• Integration tests
• E2E tests
• Linting and format checks
• Security scanning

4. Deploy

• Deploy to staging
• Smoke tests
• Deploy to production
• Health check

5. Monitor

• Log monitoring
• Error tracking
• Performance metrics
• Automatic alerts

Popular CI/CD Tools

| Tool | Type | Price | Highlight | |------|------|-------|-----------| | GitHub Actions | Cloud | Free tier | GitHub integration | | GitLab CI | Cloud/Self-hosted | Free tier | All-in-one | | Jenkins | Self-hosted | Free | Most flexible | | CircleCI | Cloud | Free tier | Fast | | Vercel | Cloud | Free tier | Best for Next.js | | Google Cloud Build | Cloud | Free tier | GCP integration |

GitHub Actions Example

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
        with:
          node-version: '20'
      - run: npm ci
      - run: npm run lint
      - run: npm run test
      - run: npm run build

  deploy:
    needs: test
    if: github.ref == 'refs/heads/main'
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Deploy to production
        run: echo "Deploy steps here"

CI/CD Best Practices

1. Run tests on every commit — Catch errors early
2. Keep pipeline fast — Under 10 minutes
3. Keep main branch always deployable
4. Work in feature branches — No direct pushes to main
5. Have a rollback plan — Always be able to revert
6. Store environment variables securely — Use secrets
7. Manage pipeline as code — Infrastructure as Code

CI/CD Metrics

| Metric | Target | |--------|--------| | Deploy frequency | Multiple per day/week | | Lead time | Short commit-to-production | | Failure rate | Low (under 2 percent) | | Recovery time | Under 1 hour | | Pipeline duration | Under 10 minutes |

Conclusion

CI/CD is essential for modern software development. With automated testing, building, and deployment, your team can release faster, safer, and more frequently. Getting started with GitHub Actions is free and easy.

For CI/CD pipeline setup and DevOps consulting, get in touch: info@cagribilgehan.com. Check out my projects: cagribilgehan.com