CI/CD Pipelines — DevOps

CI/CD eliminates "works on my machine." Continuous Integration automatically builds and tests every commit. Continuous Deployment ships passing builds to production with no human gate. The whole cycle — commit to live — takes minutes.

The Pipeline in Action

Five stages: Code ? Build ? Test ? Deploy ? Live. Press Run Pipeline to send an artifact through. Press Fail at Test to see the failure notification flow back.

drag — scroll to zoom

Code example

A GitHub Actions workflow that builds, tests, and deploys on every push to main.

CI/CD PIPELINE

# .github/workflows/deploy.yml
name: CI/CD Pipeline
on:
  push:
    branches: [main]

jobs:
  build-and-test:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Set up Node.js
        uses: actions/setup-node@v4
        with:
          node-version: '20'
          cache: 'npm'
      - run: npm ci
      - run: npm test
      - run: npm run build

  deploy:
    needs: build-and-test   # only runs if tests pass
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - name: Build Docker image
        run: docker build -t myapp:${{ github.sha }} .
      - name: Deploy to production
        run: |
          ssh deploy@prod "docker pull myapp:${{ github.sha }} && \
            docker stop app || true && \
            docker run -d --name app -p 80:3000 myapp:${{ github.sha }}"
// tests/api.test.js — runs in the Test stage
import { describe, it, expect, beforeAll, afterAll } from 'vitest';
import { createServer } from '../src/server.js';

let server;

beforeAll(async () => {
  server = await createServer({ port: 0 }); // random port
});

afterAll(() => server.close());

describe('GET /api/users/:id', () => {
  it('returns 200 with user object', async () => {
    const res = await fetch(`http://localhost:${server.port}/api/users/1`);
    expect(res.status).toBe(200);
    const body = await res.json();
    expect(body).toMatchObject({
      id: 1, name: expect.any(String)
    });
  });

  it('returns 404 for unknown user', async () => {
    const res = await fetch(`http://localhost:${server.port}/api/users/9999`);
    expect(res.status).toBe(404);
  });
});
      

Key concepts

⚙

Continuous Integration

merge — build — test

Every commit to main automatically triggers a build and test run. The goal: catch bugs within minutes of introduction, not days later during a manual release.

🚀

Continuous Deployment

ship — automate — fast

After tests pass, code deploys to production automatically — no human gate. Requires high test confidence. Some teams use Continuous Delivery instead: auto to staging, manual gate to prod.

⛔

Fail Fast

feedback — safety — block

A pipeline must block broken code. If any stage fails, it halts and notifies the team. The earlier a failure is caught (build > test > deploy), the cheaper it is to fix.

📦

Build Artifact

image — reproducible — immutable

The output of the Build stage — a Docker image, compiled binary, or zip bundle. Artifacts are versioned and immutable: what you test is exactly what you deploy.

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