socket.io/examples/cluster-nginx/nginx.conf

# Reference: https://www.nginx.com/resources/wiki/start/topics/examples/full/

worker_processes 4;

events {
  worker_connections 1024;
}

http {
  server {
    listen 80;

    location / {
      proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
      proxy_set_header Host $host;

      proxy_pass http://nodes;

      # enable WebSockets
      proxy_http_version 1.1;
      proxy_set_header Upgrade $http_upgrade;
      proxy_set_header Connection "upgrade";
    }
  }

  upstream nodes {
    # enable sticky session with either "hash" (uses the complete IP address)
    hash $remote_addr consistent;
    # or "ip_hash" (uses the first three octets of the client IPv4 address, or the entire IPv6 address)
    # ip_hash;
    # or "sticky" (needs commercial subscription)
    # sticky cookie srv_id expires=1h domain=.example.com path=/;

    server server-john:3000;
    server server-paul:3000;
    server server-george:3000;
    server server-ringo:3000;
  }
}