ws: Websockets not working with HTTPS in an Apache Proxy (302 error?)

Hello, first of all, thanks for your awesome library. I was able to setup and get WS running in a breeze. Thanks.

I have a problem with ws, I’m unable to make websockets work on an apache proxy through HTTPS. Websockets are working properly if no (apache) http(s) proxy is used.

My setup: I have an apache server with multiple virtual hosts. I have a HTTPS webpage for myserver.com and the HTTPS API with node/express/ws in api.myserver.com subdomain through the proxy, that redirects the requests to the node.js instance (multiple instances on PM2) running on port 3333.

This is my apache virtual host for the subdomain:

<VirtualHost *:443>
	ServerName api.myserver.com
	ServerAdmin hello@myserver.com
	DocumentRoot /var/www/html/myserver/api
        Options -Indexes

	SSLEngine on                                                                
	SSLProtocol all -SSLv2                                                      
	SSLCipherSuite ALL:!ADH:!EXPORT:!SSLv2:RC4+RSA:+HIGH:+MEDIUM                

	SSLCertificateFile /etc/apache2/certs/STAR_myserver_co.crt
	SSLCertificateKeyFile /etc/apache2/certs/myserver_private_key.pem
	SSLCertificateChainFile /etc/apache2/certs/STAR_myserver_co.ca-bundle
	
	SSLProxyEngine On
	ProxyPreserveHost On
	ProxyRequests Off

	# This is for websocket requests
	ProxyPass /wss/ wss://localhost:3333/
	ProxyPassReverse /wss/ wss://localhost:3333/
	
        # This is for normal requests    
        ProxyPass / https://localhost:3333/
        ProxyPassReverse / https://localhost:3333/
</VirtualHost>

This works OK for redirecting the connections to the node express backend. I have installed mod_proxy, mod_proxy_http and mod_proxy_wstunnel.

This is the node.js API backend: first, I initialize express, sessions, etc.

// express, session and mongodb session storage
var express = require('express')
var session = require('express-session')
var MongoStore = require('connect-mongo')(session)
var app = express()
// configure sessionStore and sessions, mongodb, etc...

// Certificates and credentials for HTTPS server
var fs = require('fs')
var privateKey  = fs.readFileSync(__dirname + '/certs/myserver_private_key.pem', 'utf8')
var certificate = fs.readFileSync(__dirname + '/certs/myserver_cert.pem', 'utf8')
var ca = fs.readFileSync(__dirname + '/certs/myserver_ca.pem', 'utf8')
var credentials = {key: privateKey, cert: certificate, ca: ca}

app.enable('trust proxy')
app.set("trust proxy", 1)

And then I setup the HTTPS server securely, using the same certificates that in APACHE:

// Setup HTTPS server
var https = require('https')
var server = https.createServer(credentials, app)
server.listen(appPort, 'localhost', function () {
    // Server up and running!
    var host = server.address().address
    var port = server.address().port
    console.log('myserver listening at https://%s:%s', host, port)
})

Last, I setup the websocket connections:

// setup Websockets
wss = new WebSocketServer({ server: server })
wss.on('connection', function connection(ws) {
	var cookies = cookie.parse(ws.upgradeReq.headers.cookie)
	var sid = cookieParser.signedCookie(cookies["connect.sid"], myserver_secret)
	// extract user credentials and data from cookie/sid,

	// get the session object
	sessionStore.get(sid, function (err, ss) {
		...
	})
})

Then my clients just try to connect to websockets securely (because, being a HTTPS app, I cannot use the ws:// insecure websockets connection):

window.WebSocket = window.WebSocket || window.MozWebSocket
webSocket = new WebSocket('wss://' + location.host + '/wss')

And then I get always the same error 302:

[Error] WebSocket connection to 'wss://api.myserver.com/wss' failed: Unexpected response code: 302

If I test on a local server directly to the node instance https://localhost:3333/ it’s working perfectly and websockets work as they should.

Any idea of how to solve this? Is there a problem with ws redirections made by Apache proxy modules?