3 files changed, 68 insertions, 0 deletions
diff --git a/config/application.rb b/config/application.rb
index 5d7c52c5d81..192e836594a 100644
--- a/config/application.rb
+++ b/config/application.rb
@@ -22,6 +22,7 @@ module Gitlab
     require_dependency Rails.root.join('lib/gitlab/current_settings')
     require_dependency Rails.root.join('lib/gitlab/middleware/read_only')
     require_dependency Rails.root.join('lib/gitlab/middleware/basic_health_check')
+    require_dependency Rails.root.join('config/light_settings')
 
     # Settings in config/environments/* take precedence over those specified here.
     # Application configuration should go into files in config/initializers
@@ -62,6 +63,15 @@ module Gitlab
       config.paths['app/views'].unshift "#{config.root}/ee/app/views"
     end
 
+    if LightSettings.com?
+      com_paths = config.eager_load_paths.each_with_object([]) do |path, memo|
+        com_path = config.root.join('com', Pathname.new(path).relative_path_from(config.root))
+        memo << com_path.to_s
+      end
+
+      config.eager_load_paths.push(*com_paths)
+    end
+
     # Rake tasks ignore the eager loading settings, so we need to set the
     # autoload paths explicitly
     config.autoload_paths = config.eager_load_paths.dup
diff --git a/config/initializers/0_inject_com_module.rb b/config/initializers/0_inject_com_module.rb
new file mode 100644
index 00000000000..9802eb37ec3
--- /dev/null
+++ b/config/initializers/0_inject_com_module.rb
@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require 'active_support/inflector'
+
+module InjectComModule
+  def prepend_if_com(constant, with_descendants: false)
+    return unless Gitlab.com?
+
+    com_module = constant.constantize
+    prepend(com_module)
+
+    if with_descendants
+      descendants.each { |descendant| descendant.prepend(com_module) }
+    end
+  end
+
+  def extend_if_com(constant)
+    extend(constant.constantize) if Gitlab.com?
+  end
+
+  def include_if_com(constant)
+    include(constant.constantize) if Gitlab.com?
+  end
+end
+
+Module.prepend(InjectComModule)
diff --git a/config/light_settings.rb b/config/light_settings.rb
new file mode 100644
index 00000000000..aa0dd04b3fa
--- /dev/null
+++ b/config/light_settings.rb
@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+
+class LightSettings
+  GL_HOST ||= 'gitlab.com'
+  GL_SUBDOMAIN_REGEX ||= %r{\A[a-z0-9]+\.gitlab\.com\z}.freeze
+
+  class << self
+    def com?
+      return Thread.current[:is_com] unless Thread.current[:is_com].nil?
+
+      Thread.current[:is_com] = host == GL_HOST || gl_subdomain?
+    end
+
+    private
+
+    def config
+      YAML.safe_load(File.read(settings_path), aliases: true)[Rails.env]
+    end
+
+    def settings_path
+      Rails.root.join('config', 'gitlab.yml')
+    end
+
+    def host
+      config['gitlab']['host']
+    end
+
+    def gl_subdomain?
+      GL_SUBDOMAIN_REGEX === host
+    end
+  end
+end