Connecting to MongoDb at EC2 - how do I know username, host, port, ect?

I manually installed MongoDb on EC2 micro instance using this http://docs.mongodb.org/manual/tutorial/install-mongodb-on-ubuntu/

Now I need to connect to it from a Rails application. Where do I find or set all these variables at my instance:

#mongoid.yml

production:
  host: 
  port: 
  username: 
  password: 
  database: 

As the installation instructions state the database by default listens only on the localhost interface. So you can connect only from the same host using 127.0.0.1 as host.

As stated in the Getting Started document, the default port is 27017 and the default database is test.

Also if you did not Enable Client Access Control no username and password is required.