Socket.io load balancing with Nginx Zero to Hero

I started two instances in node js at server level. Problem Faced

• Every time nginx is taking my request of socket to alternate instance

• Socket connection is on first instace

• One instance is returning 200 and other 400 for a single user due to Round Robin

Then we applied the ip_hash on nginx level

Problem Solved

• Now i have a sticky connection with the instance

• socket is working now

Problem Faced

• Connections are on different instances

• Not able to broadcast to other instance socket connections

• One to One Message only work if both the socket are on same connection

Now we have Redis in the picture

we have to use a npm module socket.io-redis

Note. This required to install redis-server as well

npm install socket.io-redis --save

Add these line after io require and before io.connection

const redis = require('socket.io-redis');
io.adapter(redis({ host: 'localhost', port: 6379 }));

Problem Solved

• now all the instances are Synced io.broadcast is working fine