i'm trying to deploy mongoid 3.0.0 app into heroku and gettting error below;

There is a configuration error with the current mongoid.yml.

Problem:
No sessions configuration provided.
Summary:
Mongoid's configuration requires that you provide details about each session that can be connected to, and requires in the sessions config at least 1 default session to exist.
Resolution:
Double check your mongoid.yml to make sure that you have a top-level sessions key with at least 1 default session configuration for it. You can regenerate a new mongoid.yml for assistance via rails g mongoid:config.

Example:
__development:
____sessions:
______default:
________database: mongoid_dev
________hosts:
__________- localhost:27017

my mongoid.yml contains;

production:
uri: <%= ENV['MONGOLAB_URI'] %>

i checked out source codes for workaround and didn't see any option to pass 'username', 'password' options also couldn't see anything about 'uri' option.

thanks