Question

Issue emitting socket.io messages on Ubuntu droplet

I recently moved my API:s from Heroku to a Ubuntu droplet provided by digital ocean. I followed these instructions on how to deploy my Node.js/Express API:s and got all of my endpoints working as expected. The only issue is that im able to connect/disconnect to the socket, but not able to emit any messages through the websockets. Everything works fine locally & in heroku with the same code, so I think the issue might be with nginx or ufw firewall.

Client code:

    const socket = socketIOClient(https://www.myapp.com/api-with-websockets);
    socket.connect();
    socket.emit('joinChannel', conversation.id);

Backend:

io.on("connection", (socket) => {
  console.log("New client connected");

  socket.on("joinChannel", (msg) => {
    console.log("New client joined channel:", msg); // <-- never gets called
    socket.join(msg);
  });

  socket.on("disconnect", () => {
    console.log("Client disconnected");
  });
});

nginx conf:

server {

        root /var/www/myapp.com/html;
        index index.html index.htm index.nginx-debian.html;

        server_name myapp.com www.myapp.com;

        location / {
                try_files $uri $uri/ =404;
        }

        location /api-with-websockets/ {
          proxy_pass http://localhost:3001/;
          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;

        }


    location /no-websockets-api/ {
        proxy_pass http://localhost:3003/;
        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;
    }

    location ~ ^/(socket\.io) {
        proxy_pass http://localhost:3001;
        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;
    }


    listen [::]:443 ssl ipv6only=on; # managed by Certbot
    listen 443 ssl; # managed by Certbot
    ssl_certificate /etc/letsencrypt/live/myapp.com/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/myapp.com/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot


}
server {
    if ($host = www.myapp.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


    if ($host = myapp.com) {
        return 301 https://$host$request_uri;
    } # managed by Certbot


        listen 80;
        listen [::]:80;

        server_name myapp.com www.myapp.com;
    return 404; # managed by Certbot

}

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Accepted Answer

Hi @bobbyiliev ! I managed to fix the issue. Turned out that my client was routing the socket path wrong. I changed the socket options to include resource path to my api and it started working. Thank for your help!

Client:

  const socketIOConnOpt = {
    'force new connection': true,
    reconnection: true,
    reconnectionDelay: 10000,
    reconnectionDelayMax: 60000,
    reconnectionAttempts: 'Infinity',
    timeout: 10000,
    transports: ['websocket'],
    resource: '/conversation-api/',
  };
const socket = socketIOClient('https://www.myapp.com', socketIOConnOpt );

Thanks for the reply @bobbyiliev

The only thing showing up in the Nginx logs is this:

2020/11/26 16:55:42 [alert] 21838#21838: *50 open socket #24 left in connection 6
2020/11/26 16:55:42 [alert] 21838#21838: *42 open socket #17 left in connection 12
2020/11/26 16:55:42 [alert] 21838#21838: *44 open socket #22 left in connection 13
2020/11/26 16:55:42 [alert] 21838#21838: *48 open socket #21 left in connection 14
2020/11/26 16:55:42 [alert] 21838#21838: aborting

I have been stuck with this issue for couple of days now and found this discussion about opening ports. When I run the command telnet google.com 3003 im not able to connect, could that maybe cause this problem? I tried opening the port 3003 ufw firewall and by running iptables -I INPUT 1 -i eth0 -p tcp --dport 3003 -j ACCEPT but still no luck.

Hi there @ollisami,

The configuration actually looks correct.

Do you see any errors in your logs? I could suggest starting with the Nginx error log, first trigger a request, and then use the following command the check the logs:

  1. sudo tail -100 /var/log/nginx/error.log

Let me know how it goes. Regards, Bobby