devtools_controller.rb

if Rails.env.development?
  class DevtoolsController < ApplicationController

    def modules
      @modules = Dir["app/assets/stylesheets/nri-modules/*.css.*"].map do |filename|
        filename =~ %r{/([^/]+)\.css}
        $1
      end
      render layout: 'text'
    end

    def module
      @module_name = params[:module_name]
    end
  end
end