Aisalkyn Aidarova

Posted on Apr 11

LAB: DevOps API Pipeline

What You Will Learn

How DevOps runs API tests in pipeline
How Docker is used
How CI/CD validates backend before deploy
Real workflow used in companies

1. PROJECT STRUCTURE

devops-api-pipeline/
├── backend/
│   ├── server.js
│   ├── package.json
│   └── Dockerfile
├── postman/
│   └── collection.json
├── .github/
│   └── workflows/
│       └── api-test.yml

2. BACKEND (same logic, slightly improved)

backend/server.js

const express = require('express');
const app = express();

app.use(express.json());

let users = [
  { id: 1, name: "John" },
  { id: 2, name: "Alice" }
];

// HEALTH CHECK (important in DevOps)
app.get('/health', (req, res) => {
  res.send("OK");
});

app.get('/users', (req, res) => {
  res.json(users);
});

app.post('/users', (req, res) => {
  const newUser = {
    id: users.length + 1,
    name: req.body.name
  };
  users.push(newUser);
  res.status(201).json(newUser);
});

app.listen(3000, () => {
  console.log("Server running on port 3000");
});

backend/package.json

{
  "name": "devops-api",
  "version": "1.0.0",
  "main": "server.js",
  "scripts": {
    "start": "node server.js"
  },
  "dependencies": {
    "express": "^4.18.2"
  }
}

3. DOCKER (IMPORTANT)

backend/Dockerfile

FROM node:18

WORKDIR /app

COPY package.json .
RUN npm install

COPY . .

EXPOSE 3000

CMD ["npm", "start"]

Build & Run locally

cd backend

docker build -t devops-api .
docker run -p 3000:3000 devops-api

Test:

http://localhost:3000/health

4. POSTMAN COLLECTION (REAL TESTS)

postman/collection.json

{
  "info": {
    "name": "DevOps API Pipeline",
    "schema": "https://schema.getpostman.com/json/collection/v2.1.0/collection.json"
  },
  "item": [
    {
      "name": "Health Check",
      "request": {
        "method": "GET",
        "url": "http://localhost:3000/health"
      }
    },
    {
      "name": "Get Users",
      "request": {
        "method": "GET",
        "url": "http://localhost:3000/users"
      }
    },
    {
      "name": "Create User",
      "request": {
        "method": "POST",
        "header": [
          { "key": "Content-Type", "value": "application/json" }
        ],
        "body": {
          "mode": "raw",
          "raw": "{ \"name\": \"CI User\" }"
        },
        "url": "http://localhost:3000/users"
      }
    }
  ]
}

5. CI/CD PIPELINE

.github/workflows/api-test.yml

name: API Test Pipeline

on:
  push:
    branches: [ "main" ]

jobs:
  test-api:
    runs-on: ubuntu-latest

    steps:
    - name: Checkout code
      uses: actions/checkout@v3

    - name: Build Docker image
      run: docker build -t devops-api ./backend

    - name: Run container
      run: |
        docker run -d -p 3000:3000 --name api devops-api
        sleep 5

    - name: Install Newman
      run: npm install -g newman

    - name: Run API tests
      run: newman run postman/collection.json

6. HOW THIS WORKS (IMPORTANT)

Step-by-step:

Code pushed to GitHub
GitHub Actions triggers pipeline
Docker builds app
Container runs API
Newman tests endpoints
If tests fail → pipeline FAILS

7. WHY THIS IS REAL DEVOPS

This is exactly what companies do:

Validate API before deployment
Prevent broken code in production
Automate testing

8. ADDITIONAL IMPROVEMENTS (REAL WORLD)

You can extend:

Add assertions in Postman

Example:

pm.test("Status is 200", function () {
    pm.response.to.have.status(200);
});

Add environment variables

"url": "{{base_url}}/users"

Add Docker push (ECR / GHCR)

9. INTERVIEW ANSWERS

Q: How do you test APIs in CI/CD?
→ Using Postman collections executed via Newman inside pipeline.

Q: Why Docker here?
→ To ensure same environment everywhere.

Q: What if API fails?
→ Pipeline stops → deployment blocked.

10. WHAT YOU JUST BUILT

You built:

API
Docker image
Automated testing pipeline
Real DevOps workflow

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