While testing MongoDB 2.2.0-rc1 in Python with the latest PyMongo driver (2.2.1) and using auth I have found that ensure_index() does not work and fails with an unauthorized error. I was testing using a test DB and user account. The same user account can create an index in the test DB without issue from the Mongo console. This code previously worked fine while running MongoDB 2.0.7 and PyMongo 2.1.1