Comment 0 for bug 1848934

Kolla Ansible should deploy Zun with Cinder Ceph support working out-of-the-box as it does for nova now.

This is more complicated than iSCSI due to RBD mapping done by host's kernel.
There are two pending ceph issues, both arise from dependency on kernel's rbd module:

- host's udev has no idea where to link rbd device unless it also has ceph-common installed (needs udev rule and a helper program with its accompanying libs - no clean solution except installing it on host)
- Cinder creates rbd volumes using the latest features while the kernel client most likely lags behind and needs a downgrade which Cinder does not currently support afaik (unless we downgrade every but this makes it less performant for the rest of the stack)

Additionally Zun (zun-compute) must access Cinder's ceph config and keyring.