docs: guide for migrating to containerized libvirt in R8/R9 migration

Author: bbezak

doc/source/operations/rocky-linux-9.rst

@@ -388,6 +388,29 @@ The possible batches depend on a number of things:
 * available spare hypervisor capacity
 * sizes of groups of compatible hypervisors
 
+Transition to Containerized Libvirt
+-----------------------------------
+
+Following is needed when migrating from Rocky Linux 8 to Rocky Linux 9 and transitioning to containerized Libvirt:
+
+1. Remove Existing Libvirt (if installed on a RL9 host)
+
+   .. code-block:: console
+
+      kayobe overcloud host command run --command "dnf remove -y libvirt libvirt-bin libvirt-daemon iscsi-initiator-utils" -b -l <hostname>
+
+2. Update kolla.yml
+
+   .. code-block:: yaml
+
+      kolla_enable_nova_libvirt_container: "{{ inventory_hostname != 'localhost' and ansible_facts.distribution_major_version == '9' }}"
+
+3. Update kolla/globals.yml
+
+   .. code-block:: yaml
+
+      enable_nova_libvirt_container: "{% raw %}{{ ansible_facts.distribution_major_version == '9' }}{% endraw %}"
+
 Potential issues
 ----------------