Health check endpoints in Node.js - Mini Project: Build & Apply

Health Check Endpoints

📖 Scenario: You are building a simple Node.js server to monitor the health of your web service. Health check endpoints help other systems know if your service is running well.

🎯 Goal: Create a Node.js server with two health check endpoints: /health and /ready. The /health endpoint returns a simple status message. The /ready endpoint returns a readiness message.

📋 What You'll Learn

Create a Node.js server using the built-in http module.

Create a variable called port set to 3000.

Add a request listener function that checks the URL path.

Respond with JSON messages for /health and /ready endpoints.

Start the server listening on the specified port.

💡 Why This Matters

🌍 Real World

Health check endpoints are used by monitoring tools and load balancers to check if your service is running and ready to receive traffic.

💼 Career

Knowing how to create health check endpoints is important for backend developers and DevOps engineers to ensure reliable and maintainable services.

1

Create the server and port variable

Create a variable called port and set it to 3000. Then create a server using http.createServer() and assign it to a variable called server.

Node.js

const http = require('http');

// Your code here

Need a hint?

Use const port = 3000; and const server = http.createServer(); to start.

2

Add a request listener function

Add a request listener function to server using server.on('request', (req, res) => { ... }). Inside the function, create a variable called url and set it to req.url.

Node.js

const http = require('http');

const port = 3000;
const server = http.createServer();

// Your code here

Need a hint?

Use server.on('request', (req, res) => { const url = req.url; }) to handle requests.

3

Add core logic for health and ready endpoints

Inside the request listener, use if and else if statements to check if url is '/health' or '/ready'. For /health, respond with status code 200 and JSON {"status": "ok"}. For /ready, respond with status code 200 and JSON {"ready": true}. For other URLs, respond with status code 404 and JSON {"error": "Not found"}. Remember to set the Content-Type header to application/json before sending the response.

Node.js

const http = require('http');

const port = 3000;
const server = http.createServer();

server.on('request', (req, res) => {
  const url = req.url;
  // Your code here
});

Need a hint?

Use if and else if to check url and respond with JSON and status codes.

4

Start the server listening on the port

Add a line to start the server listening on the port variable using server.listen(port).

Node.js

const http = require('http');

const port = 3000;
const server = http.createServer();

server.on('request', (req, res) => {
  const url = req.url;

  res.setHeader('Content-Type', 'application/json');

  if (url === '/health') {
    res.statusCode = 200;
    res.end(JSON.stringify({ status: 'ok' }));
  } else if (url === '/ready') {
    res.statusCode = 200;
    res.end(JSON.stringify({ ready: true }));
  } else {
    res.statusCode = 404;
    res.end(JSON.stringify({ error: 'Not found' }));
  }
});

// Your code here

Need a hint?

Use server.listen(port) to start the server.