Upgrading Ruby on RailsThis guide provides steps to be followed when you upgrade your applications to a newer version of Ruby on Rails. These steps are also available in individual release guides.| Ruby on Rails Guides
Notifications ActiveSupport::Notifications provides an instrumentation API for Ruby. Instrumenters To instrument an event you just need to do: ActiveSupport::Notifications.| api.rubyonrails.org
A canary release occurs when you roll out a new version of some software to a small subset of your user base to see if there are any problems before you make it available to everyone.| martinfowler.com