From: Michael Guterl <mguterl@...>
Date: 2009-12-13T00:20:01+09:00
Subject: Re: How to make a ruby program tu run unser other user:group 	different than root

On Sat, Dec 12, 2009 at 10:14 AM, Iñaki Baz Castillo <ibc@aliax.net> wrote:
> Hi, many daemons allow an argument "-u uid" which makes the program to run
> under that user. Of course this can be done just by root or privileged users.
>
> It's commonly used in init scripts. These are started by init process running
> as root and start services running under other user.
>
> However it seems that ruby binary doesn't implement such option. Is there any
> way to get it?
> If not I should use "su" command and so.
>

Here's a snippet from our unicorn config that changes the user for
workers from root to deploy.  You can probably use something from it.

  ##
  # Unicorn master is started as root, which is fine, but let's
  # drop the workers to deploy:deploy

    uid, gid = Process.euid, Process.egid
    user, group = 'deploy', 'deploy'
    target_uid = Etc.getpwnam(user).uid
    target_gid = Etc.getgrnam(group).gid
    worker.tmp.chown(target_uid, target_gid)
    if uid != target_uid || gid != target_gid
      Process.initgroups(user, target_gid)
      Process::GID.change_privilege(target_gid)
      Process::UID.change_privilege(target_uid)
    end

Best regards,
Michael Guterl