Ceph

The section [1], describes putting rbd_user and rbd_secret_uuid in nova.conf and says this is required for attaching Cinder volumes. Since OpenStack at least Icehouse this is NOT necessary for attaching RBD Cinder volumes to Nova instances. The reason for this is that the RBD Cinder volume driver will send the secret UUID and user back to Nova on the initialize_connection call. Nova can use that instead of the nova.conf values.

So to restate, this section, adding rbd_user and rbd_secret_uuid to nova.conf are NOT needed for attaching Cinder volumes going back to at least Icehouse, and are only necessary for using rbd as a Nova ephemeral backend.

[1] http://docs.ceph.com/docs/master/rbd/rbd-openstack/#configuring-nova-to-attach-ceph-rbd-block-device