Websocket on port 80 and subpath with HAProxy !

haproxy.cfg.txt

frontend mayappfront
        bind 0.0.0.0:80
        acl is_front hdr_end(host) -i myapp.fr
        acl is_websocket path_beg -i /websockets
        use_backend websocketappprod if is_websocket is_front
        use_backend backend if is_front
        default_backend backend

backend backend
        balance roundrobin
        server www1 192.168.2.19 check port 80 check inter 4000
        server www2 192.168.3.14 check port 80 check inter 4000
        server www3 192.168.4.2 check port 80 check inter 4000

listen websocketappprod 0.0.0.0:8084
        contimeout  5000
        clitimeout  500000000
        srvtimeout  500000000
        dispatch dispatch 192.168.2.20:8081