Rails production prompt change as a Rails initializer

gistfile1.rb

# Put this file in config/initializers/irb.rb
# Works in Rails 3.0+, should also work in 2.3

# Override the IRB, to provide the Rails environment in the prompt
module IRB

  class << self
    def setup_with_prompt_override(ap_path)
      setup_without_prompt_override(ap_path)
      env = (Rails.env.to_sym == :production ? "\033[00;31mPRODUCTION\033[00m" : Rails.env)
      IRB.conf[:PROMPT].keys.each do |prompt|
        IRB.conf[:PROMPT][prompt][:PROMPT_I] = "(#{env}) " + IRB.conf[:PROMPT][prompt][:PROMPT_I].to_s
        IRB.conf[:PROMPT][prompt][:PROMPT_C] = "(#{env}) " + IRB.conf[:PROMPT][prompt][:PROMPT_C].to_s
        IRB.conf[:PROMPT][prompt][:PROMPT_S] = "(#{env}) " + IRB.conf[:PROMPT][prompt][:PROMPT_S].to_s
      end
    end
    alias_method_chain :setup, :prompt_override
  end

end

FYI, this will break production 'rails s' in (at least) 3.2.8. Adding 'require IRB' before it makes it work.