node.js - socketio failed: WebSocket is closed before the connection is established on production

Question

I created an node app for websocket type project. There are no issues in my local machine, everything is working, e.g. connecting, sending and receiving but when upload to server, client is not connecting at all, it returns

WebSocket is closed before the connection is established.

below is my server code

require('dotenv').config();

const path = require('path');
const fs =    require('fs');
const options = {
    key:    fs.readFileSync(path.join(__dirname,'../'+process.env.SSL_KEY)),
    cert:   fs.readFileSync(path.join(__dirname,'../'+process.env.SSL_CRT)),
    ca:     process.env.SSL_CA
};

const http = require('https').createServer(options);
const io = require('socket.io')(http,{
    cors : {
        origin : '*'
    }
});


// middleware
io.use((socket, next) => {
    let token = socket.handshake.query.token;
    if( token == process.env.TOKEN ){
        return next();
    }

    return next(new Error('authentication error'));
});


http.listen(3800, () => {
  console.log('listening on *:3700');
});

and below is the client

<script src="https://cdnjs.cloudflare.com/ajax/libs/socket.io/3.0.4/socket.io.js" integrity="sha512-aMGMvNYu8Ue4G+fHa359jcPb1u+ytAF+P2SCb+PxrjCdO3n3ZTxJ30zuH39rimUggmTwmh2u7wvQsDTHESnmfQ==" crossorigin="anonymous"></script>

<script>
    var socket = io('mydomain.com:3800?token=myapp2021',{
        transports : ['websocket'],
        secure : true
    });

    socket.on('connect', function() {
        console.log( socket.connected );
    });
</script>

Any help, ideas, suggestions, are greatly appreciated.

question from:https://stackoverflow.com/questions/65598695/socketio-failed-websocket-is-closed-before-the-connection-is-established-on-pro

Answer 1

Did you allow incoming TCP connections at port 3800 on your server? Seems like firewall is blocking connections.