CI/CD (Continuous Integration/Continuous Deployment)

CI/CD stands for Continuous Integration and Continuous Deployment (or Delivery). It's a set of automated practices that enable development teams to deliver code changes more frequently and reliably.

Continuous Integration (CI)

What it is: Developers merge code changes into a shared repository frequently, with each change automatically built and tested.

The process:

1. Developer pushes code
2. CI system automatically:
   • Builds the code
   • Runs tests
   • Reports results
3. If anything fails, the team is notified immediately

Benefits:

• Catch bugs early
• Prevent integration nightmares
• Always have working code

Continuous Deployment (CD)

What it is: Every code change that passes tests is automatically deployed to production.

Continuous Delivery vs. Continuous Deployment:

• Delivery: Automated up to staging; manual approval for production
• Deployment: Fully automated, including production

The CI/CD Pipeline

A typical pipeline:

Code Push → Build → Test → Review → Deploy to Staging → Deploy to Production

Stages

1. Source Code pushed to repository triggers the pipeline.

2. Build Compile code, install dependencies, create artifacts.

3. Test

• Unit tests
• Integration tests
• End-to-end tests
• Security scans
• Linting/code quality

4. Deploy to Staging Release to a test environment.

5. Deploy to Production Release to live users (automatic or manual approval).

CI/CD Tools

Popular Platforms

• GitHub Actions: Built into GitHub, generous free tier
• GitLab CI: Built into GitLab
• CircleCI: Cloud-based, powerful
• Jenkins: Self-hosted, highly customizable
• Travis CI: Simple, GitHub-integrated

Cloud Provider Options

• AWS CodePipeline
• Azure DevOps
• Google Cloud Build

Example: GitHub Actions

name: CI
on: [push]
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v3
      - uses: actions/setup-node@v3
      - run: npm install
      - run: npm test
      - run: npm run build

CI/CD Best Practices

Fast Feedback

Keep pipelines quick. Slow pipelines slow everyone down.

Test Everything

Automated tests are the backbone of CI/CD confidence.

Small, Frequent Changes

Many small changes are safer than rare large ones.

Treat Pipeline as Code

Version control your pipeline configuration.

Monitor and Alert

Know immediately when things break.

Feature Flags

Deploy code without enabling features, then enable gradually.