customizing variables based on environment

Hi all,

I want to be able to customize a variable based on the environment you
are running in. Is this possible? What is the scope of a variable that
you declare in environment.rb or
environments/{production|development}.rb? I was hoping I can do
something like:

1- Declare a hash in environment.rb and specify most of the properties
i'm interested in, eg:

integration_parameters = { :url => "", :user => "john",
:password => "secret" }

2- Change whatever is needed, eg in environments/production.rb:

integration_parameters[:password] = "supersecret"

Any ideas on how to do this? Is there a more idiomatic way to do this in rails?