From: Phillip Gawlowski <pg@...>
Date: 2009-12-26T05:26:36+09:00
Subject: Re: question about multiple ruby + gems installations for dev/test/prod

On 25.12.2009 20:31, Alex Rice wrote:
> Hi All, I am pretty new to Ruby, and googled quite a bit about the gem
> utility, but am kind of stuck. I need some advice about maintaining good
> separation between ruby installs and gem directories.

http://rvm.beginrescueend.com/
Seems like that's what RVM was intended for. :)

> In this project we have Ruby installs for dev, test and prod. The idea
> is we can test different versions of ruby, rails, and different gems.
> Then when it's getting promoted from test to prod, just cp -R the ruby
> directory and all it's gems from test to prod. Nice idea except the gems
> paths are all fouled up now.
>
> Question: How does the gem script actually figure out it's environment
> and where it's gems are? Is there a config file somewhere? I can't find
> it if there is.

While I'm not aware of Rubygem's internals, I know that it does look at 
".gemrc" in the home directory of a user first, to parse variables, 
including GEM_HOME and GEM_PATH.

Coupled with RVM, this should enable you to separate your dev/test/prod 
environments on the same machine.

> I am aware of the GEM_PATH and GEM_HOME environment variables. They are
> not currently set. I have lots of shell scripts pointing at this ruby
> install, and don't want to have to add GEM_PATH and GEM_HOME to all of
> those shells scripts. However if that's the only way, then I guess I can
> live with that.

See ".gemrc" in Rubygem's manual: http://docs.rubygems.org/read/chapter/11

That should enable you to setup a .gemrc-dev, a .gemrc-testing, and a 
.gemrc-production with ease.

Alternatively, you could also use rake rails:gem:freeze to, well, freeze 
the gems your Rails app uses.

--
Phillip Gawlowski
Wishing everyone a Merry Christmas, and happy holidays :)