Mongoid
Ruby ODM framework for MongoDB
...Mongoid is customarily configured through a mongoid.yml file that specifies options and clients. The simplest configuration is as follows, which configures Mongoid to talk to a MongoDB server at “localhost:27017” and use the database named “mongoid”. If you are not using Ruby on Rails, Mongoid configuration must be loaded manually. This can be done via the Mongoid.load! method, which takes the configuration file path as its argument. It is also possible to configure Mongoid directly in Ruby, without using a configuration file. This configuration style does not support the concept of environments - whatever configuration is provided, it is applied to the current environment, but it does support defining multiple clients.