config/initializers/raven.rb

raven.rb

require 'raven'
require 'rake/task'

if Rails.env.production?
  Raven.configure do |config|
    config.dsn = 'http://xxx:xxx@app.getsentry.com/xxxxx'
  end

  module Rake
    class Task
      alias :orig_execute :execute
      def execute(args = nil)
        Raven.capture :logger => 'rake', :tags => { 'rake_task' => @name } do
          orig_execute(args)
        end
      end
    end
  end

end