Rails has had the concept of the relative_root_url / RAILS_RELATIVE_ROOT_URL for some time. In Rails 3.x (perhaps earlier as well, but I can't remember), the relative_root_url is only used to generate asset paths.
I never understood why this relative_root_url isn't also used to automatically scope all the routes? Instead I have to do it manually,
CotaApp::Application.routes.draw do MyApp scope ActionController::Base.config.relative_url_root do ... end end
Sure, you can also use rewrite rules to strip the prefix before Rails sees a url, but then how is Rails suppose to generate correct urls?