I recently received this email and thought I would share it with you because it may be relevant if you are entering the Google Cloud Developer Challenge. This blog post says that it's no longer necessary to whitelist your Google Cloud Developer Challenge application for deployment.
PHP on App Engine is now available for everyone. Take advantage of App Engine's scalability and ease of use to run PHP products like phpMyAdmin, Drupal and phpBB and frameworks like Laravel, Silex and CodeIgniter.
You can read more about it on the Google Cloud Platform Blog.