Some question about multi-ports balance and ADDITIONAL_SERVICES

[eromoe]

Hello,

1. Can I use one lb for different service (different ports) , like below

   version: '2'
   services:
     web:
       image: dockercloud/hello-world
       expose:
         - "80"
     blog:
       image: dockercloud/hello-world
       ports:
         - 8080:80
       expose:
         - "8080"
     lb:
       image: dockercloud/haproxy
       links:
         - web
         - blog
       ports:
         - 8841:80
         - 8842:8080
   

   I wrote this , but can't access by 8841 and 8842

2. If I use ADDITIONAL_SERVICES , I have to provide the docker-compose.yml 's folder name , such as project_dir ??