frontend http-in
bind 10.254.23.225:80
acl has_special_uri path_beg /special
use_backend special_server if has_special_uri
default_backend default
backend default
balance roundrobin
cookie SERVERID insert
option httpchk HEAD /check.txt HTTP/1.0
option httpclose
option forwardfor
server webA 10.254.23.4:80 cookie webA check
server webB 10.248.23.128:80 cookie webB check
backend special_server
balance roundrobin
cookie SERVERID insert
option httpchk HEAD /check.txt HTTP/1.0
option httpclose
option forwardfor
server webC 10.0.0.1:80 cookie webC check
haproxy url load balancing （url 负载均衡）
原文：http://my.oschina.net/u/142602/blog/378537