GAE - Secure data Connector and Taskqueue/Cron
'Offline' requests such as Task Queue tasks and Cron jobs have no 'user' as far as systems like SDC are concerned. If your SDC connection requires a logged in user, you will not be able to access it from a cron/task queue job.
Is it possible to use the Secure Data Connector (SDC) to access internal resources in Tasks/Cron Jobs on the Google AppEngine?
The documentation speaks about the currently logged in user but does not further elaborate this scenario.