Create a global gemset
This is where things begin to get a little tricky. What we’re going to do is create a globalgemset that contains gems that will be used across multiple projects, then a project-specificgemset for each of our Rails applications. To begin, let’s make our global gemset:
$ rvm gemset create global
$ rvm use @global
What you put in @global is up to you, but try to keep it clean. Since the point of this exercise is to maintain separate development environments for Rails 2.3 and Rails 3, don’t install any frameworks in @global. Here I’m just loading some necessities. We’ll get to a project-specific gemset momentarily.
$ gem install bundler mongrel capistrano hirb wirble
Set up your project
Thanks to Bundler, getting your Rails 3 projects configured to use your new development environment should be fairly straightforward.
First, we’ll create another gemset; this one will be specific to our Rails 3 project. Replacerails3_project with a gemset name that makes more sense for your project:
$ rvm gemset create rails3_project
$ rvm use @rails3_project
Next, create a
.rvmrc file at the root of your Rails 3 application. It will look something like this:
You can install gems with bundler from your Gemfile and skip a certain environment with
bundle install --without test
To skip multiple environments do
bundle install --without test --without development
This of course assumes you have a a gemfile something like:
group :development, :test do
group :test do
gem "rspec", ">= 2.0.0.beta.19"
Also, Michael points out that you can skip the slow “Fetching source index for http://rubygems.org/” by using “—no-update-sources”