haproxy.cfg

# in docker container this file should be located on path
# /etc/haproxy/haproxy.cfg
global
    # define connections limit
    maxconn 10000

defaults
    # http mode allow to handle websocket connections
    mode http
    retries 2
    # difine how long haproxy can wait to establish a connection
    timeout connect          5s
    timeout client          25s
    timeout server          25s

frontend http-in
    # bind connections coming to all available network interfaces on port 8888
    bind *:8888
    default_backend websockets

# difine websockets server instances
backend websockets
    # use leastconn distribute algorithm to distribute connections evenly
    # between every server instance
    balance leastconn
    # for each server set limit of 2000 connections
    server websocket_server websocket_server:8888 maxconn 2000 check