Haproxy.cfg on EC2 which NGINX run on port 81, NodeJS on port 8003.

haproxy.cfg

#
# dvv's way to configure haproxy
# Modified by yodiaditya

global
        maxconn 32768 # concurrent connections limit
        user nobody 
        spread-checks 5

defaults
        mode http
        option abortonclose
        no option accept-invalid-http-request
        no option accept-invalid-http-response
        option allbackups
        option forwardfor except 127.0.0.1 header X-Forwarded-For
        option redispatch
        retries 3
        option tcp-smart-connect


frontend all 0.0.0.0:80
        # proxy HTTP
        default_backend nginx
    
        # proxy true WebSockets and socket.io fallbacks
        acl is_websocket hdr(upgrade) -i websocket
        acl is_websocket hdr_beg(host) -i ws
        acl is_websocket hdr_end(host) -i chat.obrool.com 
    
        # N.B. the best is to place socket.io.min.js under production static server
        # so that it won't interfere here
        acl is_websocket path_beg /socket.io/
        use_backend websockets if is_websocket
    
        # TODO: how to vary depending on backend?
        #
        # client must send the data within 25 seconds. should equal server timeout
        # TODO: long upload? route to another server?
        timeout client 1d #25s

#nginx
backend nginx
       balance roundrobin
       option forwardfor # This sets X-Forwarded-For
       server nginx 127.0.0.1:81 weight 1 maxconn 1024 check  
    
       # timeouts
       option forceclose
       # server must be contacted within 5 seconds
       timeout connect 5s
       # all headers must arrive within 3 seconds
       timeout http-request 3s
       # server must respond within 25 seconds. should equal client timeout
       timeout server 25s
       #
       # don't close connection for 1 ms
       # helps to glue several short requests in one session
       # N.B. >10 can dramatically slow down short requests
       #
       timeout http-keep-alive 1
    
backend websockets
        # workers
        default-server weight 50 maxqueue 16384 maxconn 16384 slowstart 1000 inter 5000 fastinter 500 downinter 10000 rise 2 fall 3
        #
        # CONFIG: enlist workers.
        # you should copy the list from above section
        #
        server s1 127.0.0.1:8003

        # balance the load
        balance roundrobin

        # cookie persistence
        cookie SERVERID insert indirect nocache
        # timeouts
        #option forceclose
        timeout queue 5s
        # support long-polling: socket.io uses circa 20-25 second requests, lets double the time
        timeout connect 60s
        timeout server 60s