Socket.io not working with Nginx reverse proxy in front of Node.js

Question

I have my node app running on port 3000. Then I use nginx as a reverse proxy to serve the application with SSL of my domain :

server {
        listen 443 ssl;

        ssl_certificate /etc/nginx/ssl/server.chain.crt;
        ssl_certificate_key /etc/nginx/ssl/server.key;

        server_name example.com;

        location / {
                proxy_pass http://localhost:3000;
                proxy_http_version 1.1;
                proxy_set_header Upgrade $http_upgrade;
                proxy_set_header Connection 'upgrade';
                proxy_set_header Host $host;
                proxy_cache_bypass $http_upgrade;
    }
}

I initialize my socket in client-side with this line :

var socket = io.connect('https://example.com/');

And in servers-side with this line :

var io = socket_io()
app.io = io

But when I launch my application I have this error :

WebSocket connection to 'wss://example.com/socket.io/?EIO=3&transport=websocket&sid=jVNRhDOYJD20l9U-AAAA' failed: Error during WebSocket handshake: Unexpected response code: 502

Do you know how to fix this error ?

Answer 1

This article describes using nginx as a rev-proxy in front of the Kaazing WebSocket server.

https://kaazing.com/kaazing-and-nginx-the-best-of-both-worlds/

The config described in the article might be very similar to using NodeJS as the server. Hope it helps.