WebSocket with angular universal - node.js

Question

I'm trying to add websockets to a server that's using angular universal. As far as I can tell, express is consuming my request before it gets to my sockets, but I could be wrong about that.
I get this error in chrome:
WebSocket connection to 'ws://localhost:4200/socket' failed: Connection closed before receiving a handshake response
and I get this error in firefox:
Firefox can’t establish a connection to the server at ws://localhost:4200/socket.
when I run a separate nodejs server without the angular code, the websockets work fine.
Here is the relevant part of my server.ts
import 'zone.js/dist/zone-node'
import { ngExpressEngine } from '#nguniversal/express-engine'
import * as express from 'express'
import { join } from 'path'
import { AppServerModule } from './src/main.server'
import { APP_BASE_HREF } from '#angular/common'
import { existsSync } from 'fs'
import * as WebSocket from 'ws'
// The Express app is exported so that it can be used by serverless Functions.
export function app() {
const server = express()
const distFolder = join(process.cwd(), 'dist/CAHClone/browser')
const indexHtml = existsSync(join(distFolder, 'index.original.html')) ? 'index.original.html' : 'index'
// Our Universal express-engine (found # https://github.com/angular/universal/tree/master/modules/express-engine)
server.engine('html', ngExpressEngine({
bootstrap: AppServerModule,
}))
server.set('view engine', 'html')
server.set('views', distFolder)
server.use(express.json())
// Serve static files from /browser
server.get('*.*', express.static(distFolder, {
maxAge: '1y'
}))
// All regular routes use the Universal engine
server.get('*', (req, res, next) => {
if (req.url === '/socket') return next() // leave '/socket' open for the websockets
res.render(indexHtml, { req, providers: [{ provide: APP_BASE_HREF, useValue: req.baseUrl }] })
})
return server
}
function run() {
const port = process.env.PORT || 4000
// Start up the Node server
const expressApp = app()
const server = expressApp.listen(port, () => {
console.log(`Node Express server listening on http://localhost:${port}`)
})
// Websockets
const wss = setupWebsockets(server)
}
function setupWebsockets(server) {
const wss = new WebSocket.Server({ server, path: '/socket' })
wss.on('connection', ws => {
console.log('Client connected.')
ws.send({message: 'Hi there!'})
})
wss.on('message', msg => {
console.log('Client said: ' + msg.toString())
})
return wss
}
declare const __non_webpack_require__: NodeRequire
const mainModule = __non_webpack_require__.main
const moduleFilename = mainModule && mainModule.filename || ''
if (moduleFilename === __filename || moduleFilename.includes('iisnode')) {
run()
}
export * from './src/main.server'
And here is a server.js file that works without angular related code
const express = require('express')
const WebSocket = require('ws')
const { join } = require('path')
const { existsSync } = require('fs')
// The Express app is exported so that it can be used by serverless Functions.
function app() {
const server = express()
server.use(express.json())
server.use('*', (req, res, next) => {
if (req.url === '/socket') return next()
res.end('Hello, world!')
})
return server
}
function setupWebsockets(server) {
const wss = new WebSocket.Server({ server, path: '/socket' })
console.log('set up websocket server');
wss.on('connection', ws => {
console.log('Client connected.');
ws.send('Hi there!')
})
wss.on('message', msg => {
console.log('Client said: ' + msg.toString());
})
}
function run() {
const port = process.env.PORT || 4000
const expressApp = app()
const server = expressApp.listen(port, () => {
console.log(`Node Express server listening on http://localhost:${port}`)
})
// Websockets
const wsServer = setupWebsockets(server)
}
run()
Could anyone help me understand what part of angular universal is breaking my websockets, and how to fix it?

Answer 1

I ran into this issue with the 'ws' module and passing in an express server. Try creating your server with the 'http' module and pass it into both express and 'ws'. I also recommend taking care of any authorization that you are going to do in the 'upgrade' event if necessary.

Answer 2

Did you solve the matter with dev:ssr ?
It is indeed working fine with serve:ssr but the only way I made it work with dev:ssr in local development is by using a proxy from ws://localhost:4200/ws to ws://localhost:4000
{
"/ws": {
"target": "ws://localhost:4000",
"secure": false,
"ws": true
}
}
Se my question here : Angular Universal (ssr-dev-server) Setting or getting the random port of the express app in dev:ssr