haproxy.cfg.bak

global
  daemon
  maxconn 256

defaults
  mode http
  timeout connect 5000ms
  timeout client 50000ms
  timeout server 50000ms

frontend router 
  bind *:80
 
  acl www_in hdr_beg(host) www.
  acl www_in hdr_beg(host) www-dev.
  acl www_in hdr_beg(host) www-qa.
 
  acl frontend.service hdr(host) -i frontend.service
  acl backend.service  hdr(host) -i backend.service 
  
  acl env_prod hdr_beg(host) www. 
  acl env_dev  hdr_beg(host) www-dev.
  acl env_qa   hdr_beg(host) www-qa.
  acl env_prod hdr(x-mayfly) -i prod
  acl env_dev  hdr(x-mayfly) -i dev
  acl env_qa   hdr(x-mayfly) -i qa
  
  reqadd x-mayfly:\ prod if www_in env_prod
  reqadd x-mayfly:\ dev  if www_in env_dev
  reqadd x-mayfly:\ qa   if www_in env_qa
  
  use_backend frontend.service_prod if env_prod www_in
  use_backend frontend.service_dev  if env_dev  www_in
  use_backend frontend.service_prod if env_qa   www_in
  use_backend frontend.service_prod if env_prod frontend.service
  use_backend frontend.service_dev  if env_dev  frontend.service
  use_backend frontend.service_prod if env_qa   frontend.service
  use_backend backend.service_prod  if env_prod backend.service
  use_backend backend.service_dev   if env_dev  backend.service
  use_backend backend.service_dev   if env_qa   backend.service

backend frontend.service_prod
  server server1 host1.internal:5000 maxconn 32

backend backend.service_prod
  server server1 host1.internal:6000 maxconn 32

backend frontend.service_dev
  server server1 host1.internal:5001 maxconn 32

backend backend.service_dev
  server server1 host1.internal:6001 maxconn 32