Para validar url inserida no browser e direcionar ao servidor correto ajuste conforme um modo abaixo:
# vi haproxy.cfg
frontend HTTP
bind *:80
reqadd X-Forwarded-Proto:\ http <- Força trafego em http
# Caso exista algum redirecionamento para site https
redirect scheme https if { hdr(host) -i site1.com.br } !{ ssl_fc }
redirect scheme https if { hdr(host) -i www.site1.com.br } !{ ssl_fc }
redirect scheme https if { hdr(host) -i site02.com.br } !{ ssl_fc }
redirect scheme https if { hdr(host) -i www.site02.com.br } !{ ssl_fc }
## SITES HTTP ##################
acl WWW hdr(host) -i www.domain.com domain.com
use_backend WWW if WWW
acl WWW1 hdr(host) -i www.domain1.com domain1.com
option accept-invalid-http-request <- Aceita caracteres especiais na URL
use_backend WWW1 if WWW1
backend WWW
server SRV1 <IP>:80 check
backend WWW1
server SRV1 <IP>:8080 check
## SITES HTTPS #################
frontend HTTPS
bind *:443 ssl crt /etc/haproxy/certs/CERT-SITE01.pem crt /etc/haproxy/certs/CERT-SITE02.pem
reqadd X-Forwarded-Proto:\ https
acl WWW1 hdr(host) -i www.site01.com
use_backend WWW1 if WWW1
acl WWW2 hdr(host) -i www2.site02.com
acl WWW2-SUB path_beg -i /subspath
use_backend WWW2-SUB if WWW2-SUB
use_backend WWW2 if WWW2
backend WWW
server SRV1 <IP>:80 check
backend WWW2
server SRV1 <IP>:80 check
backend WWW2-SUB
server SRV1 <IP>:81 check
server SRV2 <IP>:81 check backup
Testar se o arquivo de configuração esta valido
# haproxy -c -f /etc/haproxy/haproxy.cfg
Configuration file is valid
Reinicie para validar as configurações
# /etc/init.d/haproxy restart