Multiple subdomains on 1 node.js server

Question

I would like to create a system of multiple web applications (probably around 3-5 node.js + express applications) on one server. I also only have one domain. So I figured that I need to create subdomains for each of my application apart from the main one.

My question is - how do I redirect users coming to certain subdomains to the right application? Do I need to use virtual machines and then redirect each user to a different VM (ip address) depending on their subdomain? How would I even do that?

Or could I just run every application on the same server just with a different port number? Or is there any other way that I'm not really thinking of?

Which way would be the cleanest and how would I implement it?

Answer 1

A very common way to achieve this is to run each of your node servers on a different port, and then set up a reverse proxy like nginx to have it forward requests based on matching the host header of incoming HTTP requests.

You could of course handle this manually with node, by checking the host header yourself and forwarding each request to the proper node server on the associated port.

Here is some Node code which illustrates what I'm referring to:

const http = require('http')
const url = require('url')
const port = 5555
const sites = {
  exampleSite1: 544,
  exampleSite2: 543
}

const proxy = http.createServer( (req, res) => {
  const { pathname:path } = url.parse(req.url)
  const { method, headers } = req
  const hostname = headers.host.split(':')[0].replace('www.', '')
  if (!sites.hasOwnProperty(hostname)) throw new Error(`invalid hostname ${hostname}`)

  const proxiedRequest = http.request({
    hostname,
    path,
    port: sites[hostname],
    method,
    headers 
  })

  proxiedRequest.on('response', remoteRes => {
    res.writeHead(remoteRes.statusCode, remoteRes.headers)  
    remoteRes.pipe(res)
  })
  proxiedRequest.on('error', () => {
    res.writeHead(500)
    res.end()
  })

  req.pipe(proxiedRequest)
})

proxy.listen(port, () => {
  console.log(`reverse proxy listening on port ${port}`)
})