This change reworks previous changes [1] and [2] that had
been respectively reverted and abandoned.
When using the config libvirt-image-backend=rbd, VMs
created from image have their disk data stored in ceph
instead of the compute node itself.
When performing live-migrations, both nodes need to
access the same ceph credentials to access the VM's
disk in ceph, but this is currently not possible
if the nodes involved pertain to different
nova-compute charm apps.
This patch changes app name sent to ceph to
'nova-compute-ceph-auth-c91ce26f', a unique name common to
all nova-compute apps, allowing all nova-compute apps to
use the same ceph auth.
This change also ensures newly deployed nodes install
the old credentials first on ceph-joined hook,
and then supercedes it with the new credentials
on ceph-changed hook, therefore also retaining
the old credentials.
[1] https://review.opendev.org/889642
[2] https://review.opendev.org/896155
Closes-bug: #2028559
Related-bug: #2037003
Func-Test-Pr: https://github.com/openstack-charmers/zaza-openstack-tests/pull/1190
Change-Id: I1ae12d787a1f8e7761ca06b5a80049c1c62e9e90
(cherry picked from commit 650f3a5d51)
(cherry picked from commit 28233f9a94)
(cherry picked from commit ecaf8010fc)
(cherry picked from commit 8c3549d828)
810d4b0fba