Ruby builder

[Mike Gunderloy]

I've been working towards using Cerberus to build Rails with multiple
different versions of Ruby. This requires two things that aren't in
Cerberus 0.5 (or at least, I didn't find them):

- Ability to run an arbitrary ruby script as the build command
- Ability to specify the PATH so as to put the desired Ruby
interpreter first on the list

Together with an install of multiruby, having this means that I can
execute Rails' own build file under any ruby I have installed as part
of a Cerberus build.

I've added a simple Ruby builder in my fork of the project[1].
Configuration sample:

builder:
ruby:
task: ci/ci_build.rb
ruby_path: /home/webadmin/.multiruby/install/v1_8_6_368/bin/

Hopefully this can be pulled back into the official distribution in
the next round.

[1] http://github.com/ffmike/cerberus/tree/master

[Craig Jolicoeur]

cool,

I'll pull down the code and look at getting it into an upcoming release