Added USE_DB env var to allow loading fake settings without db running.

CHANGELOG

@@ -28,6 +28,7 @@ v 8.0.0 (unreleased)
   - Fixed login failure when extern_uid changes (Joel Koglin)
   - Don't notify users without access to the project when they are (accidentally) mentioned in a note.
   - Retrieving oauth token with LDAP credentials
+  - Load Application settings from running database unless env var USE_DB=false
 
 v 7.14.1
   - Improve abuse reports management from admin area

lib/gitlab/current_settings.rb

@@ -4,7 +4,7 @@ module Gitlab
       key = :current_application_settings
 
       RequestStore.store[key] ||= begin
-        if ActiveRecord::Base.connection.active? && ActiveRecord::Base.connection.table_exists?('application_settings')
+        if connect_to_db?
           ApplicationSetting.current || ApplicationSetting.create_from_defaults
         else
           fake_application_settings
@@ -26,5 +26,17 @@ module Gitlab
         import_sources: Settings.gitlab['import_sources']
       )
     end
+
+    private
+
+    def connect_to_db?
+      use_db = if ENV['USE_DB'] == "false"
+                 false
+               else
+                 true
+               end
+
+      use_db && ActiveRecord::Base.connection.active? && ActiveRecord::Base.connection.table_exists?('application_settings')
+    end
   end
 end