Substituindo a configuração do banco de dados Rails 3 dependendo da plataforma

https://gist.github.com/1418782

configuration_extensions.rb

# lib/extenstions/configuration_extentions.rb

module Rails
  class Application
    class Configuration

      def database_configuration
        require 'erb'
        case RUBY_PLATFORM.downcase
          when /darwin/
            YAML::load(ERB.new(IO.read('config/database_mac.yml')).result)
          when /mswin/, /ming/
            YAML::load(ERB.new(IO.read('config/database_win.yml')).result)
          when /java/
            YAML::load(ERB.new(IO.read('config/database_java.yml')).result)
          else
            YAML::load(ERB.new(IO.read(paths["config/database"].first)).result)
        end
      end

    end
  end
end

environment.rb

# config/environment.rb

require 'extensions/configuration_extensions'

# Initialize the rails application