Try and use cache for application settings even when the db is not connected

app/models/application_setting.rb

@@ -98,6 +98,10 @@ class ApplicationSetting < ActiveRecord::Base
     Rails.cache.delete(CACHE_KEY)
   end
 
+  def self.cached
+    Rails.cache.fetch(CACHE_KEY)
+  end
+
   def self.create_from_defaults
     create(
       default_projects_limit: Settings.gitlab['default_projects_limit'],

lib/gitlab/current_settings.rb

@@ -9,9 +9,9 @@ module Gitlab
     end
 
     def ensure_application_settings!
-      settings = nil
+      settings = ::ApplicationSetting.cached
 
-      if connect_to_db?
+      if !settings && connect_to_db?
         settings = ::ApplicationSetting.current
         settings ||= ::ApplicationSetting.create_from_defaults unless ActiveRecord::Migrator.needs_migration?
       end