How to create a reverse proxy using clusters in Node.js

cluster-reverse-proxy.js

const cluster = require('cluster');
const http = require('http');

if (cluster.isMaster) {
  for (let i = 0; i < 10; i++) {
    cluster.fork();
  }

  let workers = Object.values(cluster.workers)
  cluster.on('exit', (worker, code, signal) => {
    console.log(`worker ${worker.process.pid} died`);
    workers = workers.filter(w => w.id !== worker.id);
  });

  const proxy = http.createServer((req, res) => {
    // Randomly send request to one of the workers
    const worker = workers[Math.floor(Math.random() * workers.length)]
    const options = {
      hostname: 'localhost',
      port: 3000 + worker.id,
      path: req.url,
      method: req.method,
      headers: req.headers
    };

    const proxyReq = http.request(options, (proxyRes) => {
      res.writeHead(proxyRes.statusCode, proxyRes.headers);
      proxyRes.pipe(res, {
        end: true
      });
    });

    req.pipe(proxyReq, {
      end: true
    });

  })
  proxy.listen(3000);

}

if (!cluster.isMaster) {
  http.createServer((req, res) => {
    res.writeHead(200);
    res.end('hello world from worker ' + cluster.worker.id);
  }).listen(3000 + cluster.worker.id);
}