CI/CD Pipeline with Jenkins for a Simple Web Application.

Step 1 : Install Jenkins and npm

Calculator app

const express = require('express');
const app = express();
const port = 3000;

app.use(express.urlencoded({ extended: true }));

app.get('/', (req, res) => {
    res.send(`
        <h1>Simple Calculator</h1>
        <form action="/calculate" method="post">
            <input type="number" name="num1" placeholder="Enter first number" required>
            <select name="operation">
                <option value="add">+</option>
                <option value="subtract">-</option>
                <option value="multiply">*</option>
                <option value="divide">/</option>
            </select>
            <input type="number" name="num2" placeholder="Enter second number" required>
            <button type="submit">Calculate</button>
        </form>
    `);
});

app.post('/calculate', (req, res) => {
    const num1 = parseFloat(req.body.num1);
    const num2 = parseFloat(req.body.num2);
    const operation = req.body.operation;

    let result;

    switch (operation) {
        case 'add':
            result = num1 + num2;
            break;
        case 'subtract':
            result = num1 - num2;
            break;
        case 'multiply':
            result = num1 * num2;
            break;
        case 'divide':
            result = num1 / num2;
            break;
        default:
            result = 'Invalid operation';
    }

    res.send(`
        <h1>Result: ${result}</h1>
        <a href="/">Go back</a>
    `);
});

app.listen(port, () => {
    console.log(`Calculator app listening at http://localhost:${port}`);
});

Add Git and store the file

Jenkins :

Go to manage jenkins

Install the following plugins:

• Git Plugin

• NodeJS Plugin

• Pipeline Plugin

Create a New Jenkins Pipeline Job:

• Go to New Item > Pipeline and name your job.

• In the pipeline section, choose Pipeline script from SCM and select Git.

• Enter the repository URL and branch to build.

Create a Jenkinsfile in your project repository:

pipeline {agent any stages { stage('Build') { steps { script { // Install dependencies sh 'npm install' } } } stage('Test') { steps { script { // Run tests (add your tests here) sh 'echo "Running tests..."' } } } stage('Deploy') { steps { script { // Deploy to a server (simple example: run the app) sh 'nohup node index.js &' } } } } }

Modified jenkinfiles and practice

pipeline { agent any stages { stage('Build') { steps { script { // Install dependencies sh 'npm install' } } } stage('Lint') { steps { script { // Run linting (replace with your actual lint command) sh 'npm run lint || echo "Linting failed, but continuing..."' } } } stage('Test') { steps { script { // Run tests (replace with your actual test command) sh 'npm test || echo "Tests failed, but continuing..."' } } } stage('Package') { steps { script { // Package the application (replace with your actual package command) sh 'npm run build || echo "Packaging failed, but continuing..."' } } } stage('Deploy') { steps { script { // Deploy to a server (simple example: run the app) sh 'nohup node index.js &' } } } stage('Cleanup') { steps { script { // Cleanup steps (optional) sh 'rm -rf node_modules' } } } } }