Where is my local App Engine datastore?
I'll restate a solution to getting permanent datastore as it worked for me (circa Feb 2017), running GoogleAppEngineLauncher on OS X v10.10.  

Create the folder path for permanent datastore
In GAEL, click on the project in question e.g. PROJECTNAME
Click Edit-Application Settings
in Extra Flags field:
--datastore_path=/Users/foo/GAE_datastore/PROJECTNAME/datastore.db

Filename has to be included; in my config, datastore.db works.
Having searched all over for GAE datastore path, and head-bonked on dev_appserver.py --datastore_path command line, it was very helpful to find this.
Application Settings under the Edit menu is an odd choice, Google :-)
How can I find where my local development datastore is located? I am using the Python SDK and Linux.