Socket.io Socket.onPacket Error with reverse proxy Nginx - node.js

Question

I have a small angular app who comunicate with a node.js server. Both are deployed on aws and I use Nginx reverse proxy to acess the node.js server at the port 4000.
All end-points of the nodejs.server works fine, except the socket.io connection.
When I run both apps (front end app and the node.js server) in my machinine the socket.io connection works fine, but when I try to deploy it on aws I get this error in the front-end app:
Error: server error
at Socket.onPacket (socket.js:401)
at XHR.<anonymous> (socket.js:216)
at XHR.push.dMso.Emitter.emit (index.js:145)
at XHR.onPacket (transport.js:103)
at callback (polling.js:101)
at Array.forEach (<anonymous>)
at XHR.onData (polling.js:105)
at Request.<anonymous> (polling-xhr.js:94)
at Request.push.dMso.Emitter.emit (index.js:145)
at Request.onData (polling-xhr.js:236)
This is my Nginx configuration in /etc/nginx/sites-available/default:
server{
charset utf-8;
listen 80 default_server;
server_name 18.231.153.164;
# angular app & front-end files
location / {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
root /opt/front-end/dist/admin;
try_files $uri /index.html;
}
# node api reverse proxy
location /api/ {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
proxy_pass http://localhost:4000/;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
# node api reverse proxy
location /socket.io {
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
proxy_set_header Host $host;
proxy_pass http://localhost:4000/;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
As you can see, my node.js is running at port 4000, so everytime someone try to access the web site with the path /api/ it will be redirected to the node.js server.
Here is a piece of my node.js code:
const socketio = require('socket.io');
const express = require('express');
const app = express();
const port = 4000;
const httpServer = app.listen(port, () => {
console.log('Server listening on port ' + port);
});
let io = socketio(httpServer, {
cors: {
origin: "http://localhost:5200",
},
});
// auth moddleware
io.use((socket, next, err) => {
const jwtToken = socket.handshake.query.jwtToken;
// console.log('token --> ', jwtToken);
const user = socket.handshake.query.user;
if (!user) {return};
socket.user = JSON.parse(user);
next();
});
io.on('connection', (socket) => {
socket.emit('messageFromServer', {data: 'Welcome to server'});
})
Here is a piece of my front-end code:
import {io} from 'socket.io-client';
...
// Connect to server (When I am running locally I change '/api' to 'http://localhost:4000'
this.socket = io('/api', {secure: true, reconnection: true, rejectUnauthorized: false, query: {user: user, jwtToken: this.authService.authValue.jwtToken}});
// Listen to events
this.socket.on('usersOnline', (usersOnline) => {
console.log('Users online now:', usersOnline);
});
this.socket.on('connect_error', (err) => {
console.log('ERR::', err);
});
The version of socket.io in the server is "^4.0.0", and the version of the socket.io-client in front and is "^4.0.0".
I believe this issue is related with the reverse proxy and socket.io somehow. As I told before, the socket.io connection works fine in local envoriment.
Can someone please help me?

Answer 1

I found the solution.
I need to add proxy_redirect off; on the socket.io reverse proxy.
location /socket.io {
proxy_pass http://localhost:4000;
proxy_redirect off;
proxy_http_version 1.1;
proxy_set_header Upgrade $http_upgrade;
proxy_set_header Connection "upgrade";
}
Then I had another problem, in the font end I start to get an error or invalid namespace.
So I change the client connection to / instead od /api:
this.socket = io('/', {query: {user: user, jwtToken: this.authService.authValue.jwtToken}});

Answer 2

Just check and install same version of socket.io and socket.io-client