Based on those release notes plus the keystone SQL it seems like the answer is _member_ (which will automagically be created when creating the Keystone DB) - that probably means changing the Horizon defaults and devstack though?
Based on those release notes plus the keystone SQL it seems like the answer is _member_ (which will automagically be created when creating the Keystone DB) - that probably means changing the Horizon defaults and devstack though?