readme.txt

# How to use
YourService::Config.config is always your config
YourService::Config.config['hello'] = true # writes your config data
YourService::Config.save! # persists do disk

config.rb

module YourService
  class Config
    class << self
      def config
        @config ||= new.config
      end
    end
    
    def config
      @config ||= YAML.load(File.read(config_file))
    end
    
    def config_file
      @config_file ||= begin
        File.expand_path(
          File.join(
            File.dirname(__FILE__, 'config.yml')
          )   
        )
      end
    end
    
    def save!
      File.open(config_file, 'w') {|f| f.write config.to_yaml }
    end
  end
end

config.yml

---
this:
  is: "Your config file"