Add cgroup delegation override

Required to solve the occasional
  libvirt: QEMU Driver error : Requested operation is not valid:
  cgroup CPUACCT controller is not mounted
problem, as per:
  https://answers.launchpad.net/ubuntu/+question/665132

roles/pvc/tasks/libvirt/main.yml

@@ -24,7 +24,7 @@
     append: yes
   with_items: "{{ admin_users }}"
 
-- name: install libvirt configuration
+- name: install libvirt configurations
   template:
     src: libvirt/{{ item }}.j2
     dest: /etc/libvirt/{{ item }}
@@ -66,6 +66,24 @@
   command: systemctl daemon-reload
   when: systemd.changed
 
+- name: create unit override configuration directory
+  file:
+    dest: /etc/systemd/system/libvirtd.service.d
+    state: directory
+
+- name: install libvirt cgroup delegation configuration
+  template:
+    src: libvirt/{{ item }}.j2
+    dest: /etc/systemd/system/libvirtd.service.d/{{ item }}
+  with_items:
+    - cgroup-delegation.conf
+  register: systemd
+  notify: restart libvirtd
+
+- name: reload systemd to apply changes
+  command: systemctl daemon-reload
+  when: systemd.changed
+
 - name: start and enable services (not managed by PVC)
   service:
     name: "{{ item }}"

roles/pvc/templates/libvirt/cgroup-delegation.conf.j2

@@ -0,0 +1,2 @@
+[Service]
+Delegate=yes