Handle missing libvirt services in evacuate hook

On Debian 13 (Trixie), libvirt packaging is modularized and
the libvirt-daemon-lock package (providing virtlockd) is
optional. The evacuate hook previously assumed all libvirt
services were installed and failed when stopping/starting
missing units.

Extract a reusable manage_libvirt_service.yaml task file that
checks if a service exists via systemctl list-unit-files
before managing its units. This prevents failures when
optional libvirt packages are not installed and future-proofs
against further packaging changes.

Generated-By: claude-code
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Change-Id: Ie84e2e8ab2d3065b1562ee5e256fa163541955f7
Signed-off-by: Sean Mooney <work@seanmooney.info>

roles/run-evacuate-hook/tasks/main.yaml

@@ -48,20 +48,27 @@
     state: destroyed
   with_items: "{{ subnode_vms.list_vms }}"
 
-- name: Stop libvirtd on "{{ inventory_hostname }}"
-  become: true
-  systemd:
-    name: "{{ item }}"
-    state: stopped
-    enabled: no
-  with_items:
+- name: Stop libvirt services on "{{ inventory_hostname }}"
+  include_tasks: manage_libvirt_service.yaml
+  vars:
+    service_name: "{{ item.name }}"
+    service_state: stopped
+    service_enabled: "no"
+    service_units: "{{ item.units }}"
+  loop:
+    - name: libvirtd
+      units:
         - libvirtd.service
         - libvirtd.socket
         - libvirtd-admin.socket
         - libvirtd-ro.socket
+    - name: virtlogd
+      units:
         - virtlogd.service
         - virtlogd-admin.socket
         - virtlogd.socket
+    - name: virtlockd
+      units:
         - virtlockd.service
         - virtlockd-admin.socket
         - virtlockd.socket
@@ -73,20 +80,27 @@
   environment:
     CONTROLLER_HOSTNAME: "{{ hostvars['controller']['ansible_hostname'] }}"
 
-- name: Start libvirtd on "{{ inventory_hostname }}"
-  become: true
-  systemd:
-    name: "{{ item }}"
-    state: started
-    enabled: yes
-  with_items:
+- name: Start libvirt services on "{{ inventory_hostname }}"
+  include_tasks: manage_libvirt_service.yaml
+  vars:
+    service_name: "{{ item.name }}"
+    service_state: started
+    service_enabled: "yes"
+    service_units: "{{ item.units }}"
+  loop:
+    - name: libvirtd
+      units:
         - libvirtd.service
         - libvirtd.socket
         - libvirtd-admin.socket
         - libvirtd-ro.socket
+    - name: virtlogd
+      units:
         - virtlogd.service
         - virtlogd-admin.socket
         - virtlogd.socket
+    - name: virtlockd
+      units:
         - virtlockd.service
         - virtlockd-admin.socket
         - virtlockd.socket

roles/run-evacuate-hook/tasks/manage_libvirt_service.yaml

@@ -0,0 +1,22 @@
+# Manage a libvirt service (stop/start) only if it is installed.
+# Parameters:
+#   service_name: base name of the service (e.g. "libvirtd", "virtlogd", "virtlockd")
+#   service_state: "stopped" or "started"
+#   service_enabled: "yes" or "no"
+#   service_units: list of unit names to manage
+
+- name: "Check if {{ service_name }} is installed"
+  become: true
+  command: systemctl list-unit-files {{ service_name }}.service
+  register: _service_check
+  ignore_errors: true
+  changed_when: false
+
+- name: "Manage {{ service_name }} units"
+  become: true
+  systemd:
+    name: "{{ item }}"
+    state: "{{ service_state }}"
+    enabled: "{{ service_enabled }}"
+  with_items: "{{ service_units }}"
+  when: _service_check is succeeded