1 files changed, 31 insertions, 0 deletions
diff --git a/actionpack/lib/sprockets/railtie.rb b/actionpack/lib/sprockets/railtie.rb
index 4eb302d4a6..5006a3a575 100644
--- a/actionpack/lib/sprockets/railtie.rb
+++ b/actionpack/lib/sprockets/railtie.rb
@@ -1,9 +1,40 @@
 require "sprockets"
 
+# TODO: Move this to sprockets-rails
+# If so, we can move the require to a Gemfile and remove assets.enabled
 class Sprockets::Railtie < Rails::Railtie
+  # Configure ActionController to use sprockets.
   initializer "sprockets.set_configs", :after => "action_controller.set_configs" do |app|
     ActiveSupport.on_load(:action_controller) do
       self.use_sprockets = app.config.assets.enabled
     end
   end
+
+  # We need to configure this after initialization to ensure we collect
+  # paths from all engines. This hook is invoked exactly before routes
+  # are compiled.
+  config.after_initialize do |app|
+    assets = app.config.assets
+    next unless assets.enabled
+
+    app.assets = asset_environment(app)
+    app.routes.append do
+      mount app.assets => assets.prefix
+    end
+
+    if config.action_controller.perform_caching
+      app.assets = app.assets.index
+    end
+  end
+
+  protected
+
+  def asset_environment(app)
+    assets = app.config.assets
+    env = Sprockets::Environment.new(app.root.to_s)
+    env.static_root = File.join(app.root.join("public"), assets.prefix)
+    env.paths.concat assets.paths
+    env.logger = Rails.logger
+    env
+  end
 end
 \ No newline at end of file