I would like to ask which kind of credentials do I need to put on for importing data using the Google App Engine BulkLoader class
appcfg.py upload_data --config_
You need create an admin credential in your local development server first.
With your firefox (or chrome safari etc), open http://localhost:8178/remote_api, you will be asked to login (without password), enter an email as your login, and tick the login as administrater
box, login. This will create you a local admin credential for you, use this when bulkloading locally.
It applies to other admin required local access.
Leaving (or commenting) out login:admin
is a bad practice, since you might deploy that into production, too. Take care!