Socket.io + NodeJS doesn't work on Heroku

Question

I am doing an API and it's on Heroku. But I am having some problems with the socket.io only on the heroku side, when I test it in local everything goes fine. The API is completely independent of the frontend, so they are in a different domains (and a different hosts). The problem is that on production, I don't get succeed in connect the sockets...

I have some questions, all of that are about the socket.io configuration on heroku. I know that there are some posts with some information about that, but the posts I found it was with old versions of sockets.io or old versions of heroku (heroku seems to has changed the websockets stuff the past July):

• I don't know if I need to activate something before run socket.io on heroku. I read some posts about that, but all seems to be old... I tried to activate Websockets with: $ heroku labs:enable websockets but the response that I got it was: ! No such feature: websockets.

• Do I have to specify a port, or Heroku has an automatic port for that?

• Do I need two connections? One to listen the POST/GET/PUT/DELETE and another to the sockets?

app.js

    var express = require('express');
    var app = module.exports = express();
    var port = process.env.PORT || 5000;
    var port_s = 3000;
    var server = require('http').createServer(express);
    ...
    app.listen(port);
    server.listen(port_s);

    require('./config/socket-io')(app, server, secret);
    app.post('/user', routes.users.register);
    ...

socket-io.js

module.exports = function(app, server, secret) {
    var clients = {};
    console.log("initiating sockets...");
    var sio = require('socket.io').listen(server);

    sio.sockets.on('connection', function (socket) {
        clients[socket.id] = socket;
        console.log("...new connection: "+socket.client.id);
        socket.emit('identification', { data : socket.client.id });

        socket.on('newShoutOut', function(data) {
            var receptor    = data.idTo;
            var emiter      = socket.client.id;
            //console.log("...new shout out from " +emiter+ " to "+receptor);
            var elem = findElement(sio.sockets['sockets'], 'id', receptor);
            sio.sockets.sockets[elem].emit('privateShoutout',{ data : data.data, from : emiter });
        });

        socket.on('disconnect', function() {
            //console.log("..."+socket.client.id + " disconnected");
        });
    });
};

function findElement(arr, propName, propValue) {
    for (var i=0; i < arr.length; i++) {
        if (arr[i].id === propValue)
            return i;
    };
}

I repeat, everything works on localhost. I tried the API on localhost:5000 and the client app on localhost:80 and all the sockets work fine.

Thank you.

Answer 1

So there's a couple things here. If you'd like to use Heroku's Websocket service (which is pretty great actually), you're going to need to rework your code to use the einaros/ws implementation of websockets--and then add the service via heroku command line. https://github.com/einaros/ws/blob/master/doc/ws.md

however, since you've already coded your app to socket.io, I would simply rework how you're instantiating the socket.io library:

var express = require('express'),
    app = express(),
    server = require('http').createServer(app),
    io = require('socket.io').listen(server),

server.listen(process.env.PORT || 3000);

This should solve your issue, but let me know what the logs show. I think the hang up is that your app, and your socket are running on two different ports.

After you've created your sever, you can listen for socket events with:

io.sockets.on('connection', function(socket) { //'connection' or any other event

Hope this helps.