Chat project - load balance with socket.io

Question

I am involved in a development project of a chat where we are using node.js, socket.io (rooms) and mongodb. We are at the stage of performance testing and we are very concerned if the system needs a load balance.

How can we develop if our project needs it? J'a researched on NGINX looks cool, but we are in doubt whether solves our problem as how the system will be a chat, we fear the servers are not ~talking~ with each other correctly ...

Where do we go if we need a load balancing?

Answer 1

To ensure that we can scale to multiple nodes but keep up interconnectivity between different clients and different servers, I use redis. It's actually very simple to use and set up.

What this does is creates a pub/sub system between your servers to keep track of your different socket clients.

var io = require('socket.io')(3000),
    redis = require('redis'),
    redisAdapter = require('socket.io-redis'),
    port = 6379,
    host = '127.0.0.1',
    pub = redis.createClient(port, host),
    sub = redis.createClient(port, host, {detect_buffers: true}),
    server = http(),
    socketServer = io(server, {adapter: redisAdapter({pubClient: pub, subClient: sub})});

read more here: socket.io-redis

As far as handling the different node servers, there are different approaches.

• AWS ELB(elastic load balancer)
• Nginx
• Apache
• HAProxy

Among others...

Answer 2

Check out the NPM package mong.socket.io . It has the ability to save socket.io data to mongoDB like below;

{
    "_id" : ObjectId("54b901332e2f73f5594c6267"),
    "event" : "join",
    "message" : {
            "name" : "join",
            "nodeId" : 426506139219,
            "args" : "[\"URAiA6mO6VbCwquWKH0U\",\"/54b6821asdf66asdasd2f0f9cd2997413780273376\"]"
    }}

Or you may use the redis adapter as mentioned there;

Socket.IO Using multiple nodes

Then just use the NGINX reverse proxy and all of the node processes should share Socket.IO events with each other.