rosa-build/app/models/event_log_observer.rb

class EventLogObserver < ActiveRecord::Observer
  observe :user, :private_user, :platform, :repository, :project, :product, :build_list, :auto_build_list, :product_build_list

  def after_create(record)
    ActiveSupport::Notifications.instrument("event_log.observer", :object => record)
  end

  def before_update(record)
    case record.class.to_s
    when 'BuildList'
      if record.status_changed? and  [BuildList::BUILD_CANCELED, BuildList::BUILD_PUBLISHED].include?(record.status)
        ActiveSupport::Notifications.instrument("event_log.observer", :object => record)
      end
    when 'Platform'
      if record.visibility_changed?
        ActiveSupport::Notifications.instrument "event_log.observer", :object => record,
          :message => I18n.t("activerecord.attributes.platform.visibility_types.#{record.visibility}")
      end
    end
  end

  def after_destroy(record)
    ActiveSupport::Notifications.instrument("event_log.observer", :object => record)
  end
end