Support Cinder with Ceph and Nova without Ceph

[berendt]

Related to #711

[Nils98Ar]

We still would like to configure local ssd. Nova should use raw images as storage backend (local ssd) globally on all compute nodes. Cinder should still use ceph.

It seems that this is not possible yet. When deploying the config with osism apply nova -l compute01* the following task fails. Similar to what @killermoehre observed in https://github.com/osism/issues/issues/711#issue-1932568936.

TASK [nova-cell : Pushing secrets key for libvirt] *****************************
fatal: [compute01]: FAILED! => {"censored": "the output has been hidden due to the fact that 'no_log: true' was specified for this result"}

Setup/Config:

All compute nodes are eqipped with local ssds mounted to /var/lib/nova and we only have diskless flavors + ssd flavors in our cloud.

environments/kolla/configuration.yml

enable_ceph: "no"

cinder_backend_ceph: "yes"
nova_backend_ceph: "no"

nova_instance_datadir_volume: /var/lib/nova

environments/kolla/files/overlays/nova/nova-compute.conf

[libvirt]
images_type = raw
disk_cachemodes = "file=writethrough, block=writethrough, network=writethrough"

[Nils98Ar]

Maybe this one breaks it somehow?

https://github.com/osism/container-image-kolla-ansible/blob/1fe568470ae8d5e542382b85069e066eef567c9a/patches/2023.1/external-ceph-host-specific.patch#L221

[Nils98Ar]

Moving nova_backend_ceph: "no" to the compute nodes host_vars in inventory/host_vars/<compute node>.yml and keep nova_backend_ceph: "yes" in the environments/kolla/configuration.yml is a workaround.