Rocket Chat sticky load balancing with docker-compose and haproxy

docker-compose.yml

version: '2'

services:
  rocketchat1:
    image: rocketchat/rocket.chat:0.65.1
    restart: unless-stopped
    volumes:
      - ./uploads:/app/uploads
    environment:
      - PORT=3000
      - ROOT_URL=http://192.168.64.28
      - MONGO_URL=mongodb://mongo:27017/rocketchat
      - MONGO_OPLOG_URL=mongodb://mongo:27017/local
    depends_on:
      - mongo

  rocketchat2:
    image: rocketchat/rocket.chat:0.65.1
    restart: unless-stopped
    volumes:
      - ./uploads:/app/uploads
    environment:
      - PORT=3000
      - ROOT_URL=http://192.168.64.28
      - MONGO_URL=mongodb://mongo:27017/rocketchat
      - MONGO_OPLOG_URL=mongodb://mongo:27017/local
    depends_on:
      - mongo

  mongo:
    image: mongo:latest
    restart: unless-stopped
    volumes:
     - ./data/runtime/db:/data/db
     - ./data/dump:/dump
    ports:
     - 27017:27017
    command: mongod --smallfiles --oplogSize 128 --replSet rs0

  haproxy:
    image: haproxy:1.4.27
    restart: unless-stopped
    volumes:
     - ./haproxy.conf:/usr/local/etc/haproxy/haproxy.cfg:ro
    ports:
     - 80:80

haproxy.conf

# Requires recent Haproxy to work with websockets (for example 1.4.16).

#global
#  log /dev/stdout
#    log 127.0.0.1 local2 debug

defaults
    log global
    mode http
    option httplog
    option dontlognull
    retries 3
    option redispatch
    # Set timeouts to your needs
    timeout client  60s
    timeout connect 60s
    timeout server  60s

frontend all 0.0.0.0:80
    mode http
    timeout client 120s
#    option httplog

    option forwardfor
    # Fake connection:close, required in this setup.
    #option http-server-close
    #option http-pretend-keepalive

    acl is_websocket path_beg /sockjs
    acl is_websocket hdr(Upgrade) -i WebSocket
    acl is_websocket hdr_beg(Host) -i ws
    acl is_stats  path_beg /haproxy_stats

    use_backend websockets if is_websocket
    use_backend stats if is_stats
    default_backend meteor


backend meteor
    balance source
    server rocketchat1 rocketchat1:3000 weight 1
    server rocketchat2 rocketchat2:3000 weight 1

backend websockets
  balance source
  option http-server-close
  option forceclose
  server rocketchat1 rocketchat1:3000 weight 1
  server rocketchat2 rocketchat2:3000 weight 1

backend stats
    stats uri /haproxy_stats
    stats enable