How can I disable logging of asset pipeline (sprockets) messages in Ruby on Rails 3.1?

Question

Sprockets tends to be quite verbose in the (dev) log by default under Ruby on Rails 3.1 (RC1):

Started GET "/assets/application.css" for 127.0.0.1 at 2011-06-10 17:30:45 -0400
Compiled app/assets/stylesheets/application.css.scss  (5ms)  (pid 6303)


Started GET "/assets/application.js" for 127.0.0.1 at 2011-06-10 17:30:45 -0400
Compiled app/assets/stylesheets/default.css.scss  (15ms)  (pid 6303)

...
Started GET "/assets/default/header_bg.gif" for 127.0.0.1 at 2011-06-10 17:30:45 -0400
Served asset /default/header_logo.gif - 304 Not Modified  (7ms)  (pid 6303)
Served asset /default/header_bg.gif - 304 Not Modified  (0ms)  (pid 6246)
Served asset /default/footer_bg.gif - 304 Not Modified  (49ms)  (pid 6236)
...

I'd like to either reduce the level of verbosity or disable it altogether.

I'm assuming there is a clean way to disable or reduce the verbosity of the logging by adding a config line in either environment.rb or development.rb similar to config.active_record.logger = nil which silences ActiveRecord SQL statements.

Answer 1

Place the following code in config/initializers/quiet_assets.rb

if Rails.env.development?
  Rails.application.assets.try(:logger=, Logger.new('/dev/null'))
  Rails::Rack::Logger.class_eval do
    def call_with_quiet_assets(env)
      previous_level = Rails.logger.level
      Rails.logger.level = Logger::ERROR if env['PATH_INFO'] =~ %r{^/assets/}
      call_without_quiet_assets(env)
    ensure
      Rails.logger.level = previous_level
    end
    alias_method_chain :call, :quiet_assets
  end
end

Updated: It now works for Ruby on Rails 3.2 too (previous attempt fixes before_dispatch, and now we're going for the root rack call instead)

Update: A proper Rack middleware solution (instead of fragile alias_method_chain) from @macournoyer https://github.com/rails/rails/issues/2639#issuecomment-6591735