Currently the logging library is writing files to a magical path: /var/log/app_engine/. This is not an official supported path, and would only work for App Engine. At any point -that path could stop working.

The only officially supported ways to write logs are to write to stdout or stderr, or to use the cloud logging APIs. Come chat with me if you have questions!

https://github.com/GoogleCloudPlatform/google-cloud-python/blob/master/logging/google/cloud/logging/handlers/app_engine.py#L34