Rails 3 comes with baked in support with bundler.
Using Bundler with Rails 3
Install Rails as you normally would. Use sudo if you would normally use sudo to install gems.
$ gem install rails
We recommend using rvm for dependable Ruby installations, especially if you are switching between different versions of Ruby
Generate a Rails app as usual
$ rails new myapp $ cd myapp
Run the server. Bundler is transparently managing your dependencies!
$ rails server
Add new dependencies to your Gemfile as you need them.
gem "nokogiri" gem "geokit"
If you want a dependency to be loaded only in a certain Rails environment, place it in a group named after that Rails environment
group :test do gem "rspec" gem "faker" end
After adding a dependency, if it is not yet installed, install it
$ bundle install
This will update all dependencies in your Gemfile to the latest versions that do not conflict with other dependencies