user-service.js

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

const users = ['Aras', 'Arsy', 'Dimas', 'Ivan', 'Rafy', 'Gilang'];
const MISSING = 4;

const server = http.createServer((req, res) => {
    const { pathname } = url.parse(req.url);
    let id = pathname.match(/^\/(\d+)$/);
    if (!id) {
        res.statusCode = 400;
        return void res.end();
    }

    id = Number(id[1]);

    if (id === MISSING) {
        res.statusCode = 404;
        return void res.end();
    }

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

    res.end(JSON.stringify({
        id,
        name: users[id % users.length],
    }));
});

server.listen(process.env.PORT || 0, () => {
    const { port } = server.address();
    console.log(`User service listening on localhost on port: ${port}`);
});