ActiveStorage: Old urls still request deprecated :combine_options in variation_key

Question

Recently I upgraded from Rails 6.0.3.4 to 6.1.3. ActiveStorage deprecated combine_options, which I cleared from my app. All fresh request work as expected. Internet Bots (Facebook, Google, ...) cache urls to images hosted on a website (like mine). According to my Rollbar records they request these a couple of times a day.

The cached URL's that should load ActiveStorage attachments include an old variation_key in the URL. When the blob wants to load using the decoded variation_key, I see that combine_options is still present. This throws a 500 Internal Server Error with ArgumentError (Active Storage's ImageProcessing transformer doesn't support :combine_options, as it always generates a single ImageMagick command.):.

Is there any way I can stop these errors from showing up?

Rails version: 6.1.3. Ruby version: 2.7.2p137

Answer 1

I have resolved this issue using some middleware. This will intercept all incoming requests, scan if they are ActiveStorage urls, find the ones with the deprecated combine_options and just return 404 not found. This code will also raise an error is the current environment is development, this way I don't accidentally introduce the deprecated code again.

For those of you who might have the same problem, here's the code.

application.rb

require_relative '../lib/stopper'
config.middleware.use ::Stopper

lib/stopper.rb

class Stopper
  def initialize(app)
    @app = app
  end

  def call(env)

    req = Rack::Request.new(env)
    path = req.path

    if problematic_active_storage_url?(path)
      if ENV["RACK_ENV"] == 'development'
        raise "Problematic route, includes deprecated combine_options"
      end
      [404, {}, ['not found']]
    else
      @app.call(env)
    end
  end

  def problematic_active_storage_url?(path)
    if active_storage_path?(path) && !valid_variation_key?(variation_key_from_path(path))
      return true
    end
    false
  end

  def active_storage_path?(path)
    path.start_with?("/rails/active_storage/representations/")
  end

  def variation_key_from_path(path)
    if path.start_with?("/rails/active_storage/representations/redirect/")
      path.split('/')[6]
    elsif path.start_with?("/rails/active_storage/representations/")
      path.split('/')[5]
    end
  end

  def valid_variation_key?(var_key)
    if decoded_variation = ActiveStorage::Variation.decode(var_key)
      if transformations = decoded_variation.transformations
        if transformations[:combine_options].present?
          return false
        end
      end
    end
    true
  end
end