config/preinitializer.rb

begin
require 'rubygems'
require 'bundler'

rescue LoadError
raise "Could not load the bundler gem.  Install it with `gem install bundler`."
end

if Gem::Version.new(Bundler::VERSION) <= Gem::Version.new("0.9.24")
raise RuntimeError, "Your bundler version is too old for Rails 2.3.\n" + 
"Run `gem bundler` to upgrade."
end

begin
# Set up load paths for all bundled gems
ENV["BUNDLE_GEMFILE"] = File.expand_path("../../Gemfile", __FILE__);
Bundler.setup

rescue Bundler::GemNotFound
raise RuntimeError, "Bundler couldn't find some gems.\n" + 
"Did you run `bundle install`?"
end