Running Foreman with Unicorn

Hi, I've tried to build passenger free environment so ran puppet + unicorn

  • nginx
    When trying to run Foreman with Unicorn i received You have already
    activated rack 1.5.2, but your Gemfile requires rack 1.2.8
    after downgrading the rack i recieved
    `establish_connection': development database is not configured

exported environment and it ran ok.
So i can export variables in startup script.

but how to manage rack downgrade ?
I would not like to ran it with outdated version.

Any ideas?