Connect two node apps via websocket with via nginx ssl terminating proxy

Question

Want a node app on host A to talk to another node app on host B using a websocket (no web app involved). The host B sits behind an SSL configured reverse proxy (nginx).

Below is the configuration I have. Am using the 'ws' module for websockets.

I get a successful connection using curl from host A. When I run the node app on host A it returns an error. Therefore at present I assume my nginx.conf and the node app on host B are OK and the issue is the node app client on host A.

How to make it work?

node server app

var web = (function() {
    var express = require('express');
    return {
        app: express(),
        express: express
    };
})();

var server = web.app.listen(3000, function(){
  console.log('Example app listening on port 3000!');
});

const wss = new SocketServer({ server });
wss.on('connection', function connection(ws) {
    console.log("connection ...");
    ws.on('message', function incoming(message) {
        console.log('received: %s', message);
        connectedUsers.push(message);
    });
    ws.send('message from server at: ' + new Date());
});

nginx proxy

server {
    listen       443 ssl http2 default_server;
    listen       [::]:443 ssl http2 default_server;
    server_name  any.com;
    ssl_certificate "/etc/pki/nginx/ssl/cert/SSL_Certificate.crt";
    ssl_certificate_key "/etc/pki/nginx/ssl/private/any.com.key";
    ssl_protocols TLSv1.1 TLSv1.2;
    ssl_ciphers 'EECDH+AESGCM:EDH+AESGCM:AES256+EECDH:AES256+EDH';
    ssl_prefer_server_ciphers on;
    ssl_session_cache shared:SSL:10m;
    location /app/wss/ {
        proxy_pass                          http://localhost:3000/;
        proxy_http_version 1.1;
        proxy_set_header Upgrade websocket;
        proxy_set_header Connection upgrade;
    }
}

node client app

const WebSocket = require('ws');
wsClient = new WebSocket('wss://any.com/app/wss');
wsClient.on('open', function open() {
    console.log('open connection, sending message to server...');
    wsClient.send('something from client');
});
wsClient.on('message', function incoming(data) {
    console.log('clientreceived message from server:'+data);
});

node client app error

node app
events.js:160
      throw er; // Unhandled 'error' event
      ^

Error: Unexpected server response: 301
    at ClientRequest.req.on (/home/xxx/projects/app/node_modules/ws/lib/websocket.js:542:5)
    at emitOne (events.js:96:13)
    at ClientRequest.emit (events.js:188:7)
    at HTTPParser.parserOnIncomingClient [as onIncoming] (_http_client.js:474:21)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:99:23)
    at TLSSocket.socketOnData (_http_client.js:363:20)
    at emitOne (events.js:96:13)
    at TLSSocket.emit (events.js:188:7)
    at readableAddChunk (_stream_readable.js:176:18)
    at TLSSocket.Readable.push (_stream_readable.js:134:10)

successful curl and response

curl --include --no-buffer --header "Connection: Upgrade" --header "Upgrade: websocket" --header "Host: localhost:3000" 
    --header "Origin: http://example.com:80" --header "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" 
    --header "Sec-WebSocket-Version: 13" https://any.com/app/wss/

HTTP/1.1 101 Switching Protocols
Server: nginx/1.12.1
Date: Fri, 26 Oct 2018 23:25:05 GMT
Connection: upgrade
Upgrade: websocket
Sec-WebSocket-Accept: qGEgH3En71di5rrssAZTmtRTyFk=

�?message from server at: Fri Oct 26 2018 23:25:05 GMT+0000 (UTC)^C

Answer 1

I found after adding a / to the URL in the client app it worked, changed this:

wsClient = new WebSocket('wss://any.com/app/wss');

To this:

wsClient = new WebSocket('wss://any.com/app/wss/');

Not sure what objects to this upstream. It's either the reverse proxy nginx or the server app. It also fails when I replicate the same URL into the (slimmed down) curl command:

curl --include --no-buffer --header "Connection: Upgrade" --header "Upgrade: websocket" --header "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" --header "Sec-WebSocket-Version: 13" https://any.com/app/wss
HTTP/1.1 301 Moved Permanently
Server: nginx/1.12.1
Date: Sat, 27 Oct 2018 17:19:22 GMT
Content-Type: text/html
Content-Length: 185
Location: https://any.com/app/wss/
Connection: keep-alive

<html>
<head><title>301 Moved Permanently</title></head>
<body bgcolor="white">
<center><h1>301 Moved Permanently</h1></center>
<hr><center>nginx/1.12.1</center>
</body>
</html>

So by a chance mistake I had a different URL in the curl command versus the node client app which was initially made the former method work.