Run a project-specific IRB config in Rails 3.1+

irbrc.rb

if ENV['RAILS_ENV']
  rails_env = ENV['RAILS_ENV'].downcase
elsif Rails and Rails.env
  rails_env = Rails.env.downcase
end

if rails_env
  current_app = "myapp"

  black = "\[\033[0;30m\]"
  red = "\[\033[0;31m\]"
  green = "\[\033[0;32m\]"
  yellow = "\[\033[0;33m\]"
  blue = "\[\033[0;34m\]"
  purple = "\[\033[0;35m\]"
  cyan = "\[\033[0;36m\]"
  reset = "\[\033[0;0m\]"

  environment_color = case rails_env
                        when 'development'
                          green
                        when 'staging'
                          yellow
                        when 'production'
                          red
                        else
                          red
                      end

  rails_env = {'development' => 'dev', 'staging' => 'staging', 'production' => 'prod'}.fetch(rails_env) { 'unknown' }

  IRB.conf[:PROMPT][:RAILS_ENV] = {
      :PROMPT_I => "#{green}#{current_app}#{environment_color}(#{rails_env})#{reset}> ",
      :PROMPT_N => "#{green}#{current_app}#{environment_color}(#{rails_env})#{reset}> ",
      :PROMPT_S => nil,
      :PROMPT_C => "?> ",
      :RETURN => "=> %s\n"
  }

  IRB.conf[:PROMPT_MODE] = :RAILS_ENV
end

run_irb_config.rb

# Works on Heroku!

module MyAppName
  class Application < Rails::Application
    def load_console(app=self)
      super
      ARGV.push "-r", File.join(Rails.root, ".irbrc.rb")
    end
  end
end

I'm on it.. :)