Rails 2.3-style plugins and deprecation warnings running task in Heroku

Question

Are you using Heroku?

Heroku will inject plugins in Rails 3.x applications .. To avoid this injection in Rails 3, include the rails_12factor gem in your application. (Heroku Ruby Support 2013-10-26)

The rails_12factor gem is also required in rails 4.

If this gem is not present in your application, you will receive a warning while deploying, and your assets and logs will not be functional. (Rails 4 on Heroku 2013-10-26)

As recently as 2013-08, heroku always injected plugins in rails 3 apps, even apps with the recommended gems. This was an issue with the ruby buildpack, and was fixed by PR 11, merged on 2013-08-06.

You can try

::ActiveSupport::Deprecation.silenced = true

in your production.rb since it's just noise.

in config/environment.rb add:

ActiveSupport::Deprecation.silenced = true 

before initializing rails, like so:

# Load the rails application                                                                                                                                             
require File.expand_path('../application', __FILE__)

ActiveSupport::Deprecation.silenced = true                                                                                                                               

# Initialize the rails application                                                                                                                                       
MyApp::Application.initialize!

Similarly to disable warnings in rake tasks insert the silencing config near the top of your Rakefile:

# Load the rails application                                                                                                                                             
require File.expand_path('../application', __FILE__)

ActiveSupport::Deprecation.silenced = true                                                                                                                           

# Initialize the rails application                                                                                                                                       
MyApp::Application.initialize!

You can optionally wrap this in a block to only silence in production:

if ENV['RAILS_ENV'] == "production"
  ActiveSupport::Deprecation.silenced = true
end

The best approach I have found is documented here. This is assuming you searched and found this question because you do have old-style plugins.

I went with the Make it not a gem at all part, because I needed to be able to turn plugins on/off during my capistrano deployment, based on what flavor of the app I was deploying. Before I used config.plugins to specify what plugin to use. With this approach I'm using a "require" on config.before_configuration instead.

Just put following monkey patch into /lib/silence_heroku_warnings.rb

module Rails
  class Plugin < Engine

    alias :not_silenced_initialize :initialize

    def initialize(root)
      ActiveSupport::Deprecation.silence{ self.send :not_silenced_initialize, root }
    end

  end
end

and require it in config/application.rb just after requiring Rails:

require 'rails/all'
require File.expand_path('../../lib/silence_heroku_warnings', __FILE__)

All deprecations from 2.x-style plugins should be silenced. Other deprecations will show up.

A cleaner way than just silencing warnings, here is what you can do.

For the logger injection you can try to use Heroku's new gem that Jared Beck mentioned in his reply above.

What we did instead is this:

You can inhibit Heroku from injecting its own plugins if you have a directory by the same name in your vendor/plugins folder. The folder just needs to exist. Heroku then will not inject its plugin, and if there is no code, Rails won't object with deprecation warnings. We just put a readme file explaining this into:

vendor/plugins/rails_log_stdout/readme.md

The purpose of Heroku's injected plugin for logging is to turn on Heroku-style logging (it requires logs to be sent to STDOUT, not to a file). To get that back, we did what I described in this answer. Tweaks to Heroku's default behaviors were needed for Unicorn anyway, so we got two birds in one stone.