Rails 2.3 comes with its own gem handling. We're going to
override that and replace it with support for Bundler.
NB: This may work with Rails versions lower than 2.3.
The Bundler team has not tested those versions, and will not provide
support for anyone on Rails older than 2.3, but feel free to try it. :)
If you don't have a Rails 2.3 app yet, generate one
$ rails myapp
$ cd myapp
Insert the following code at the bottom of config/boot.rb,
right above the line `Rails.boot!`
@bundler_loaded ||= Bundler.require :default, Rails.env
Create a new file,
and insert the following. That is
raise "Could not load the bundler gem. Install it with `gem install bundler`."
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 install bundler` to upgrade."
ENV["BUNDLE_GEMFILE"] = File.expand_path("../../Gemfile", __FILE__)
raise RuntimeError, "Bundler couldn't find some gems.\n" +
"Did you run `bundle install`?"
Get all config.gem declarations from your application, and place
them into the Gemfile. If you have declarations in development.rb,
for instance, place them in a named group. Make sure to include
Rails itself and at least one source
gem 'rails', '~> 2.3.5'
gem 'sqlite3-ruby', :require => 'sqlite3'
group :development do
group :test do
Learn More: Groups
Once you have everything set up, you can use script/console,
script/server, and other Rake tasks as usual. From this point
on, you can follow the instructions in the Rails 3 guide
$ rake db:migrate
Learn More: Rails 3