Prevent lxc.service from being restarted on package update

As of today, each lxc-utils update would lead to restart of all
containers. At the same time this might be unwanted behaviour, as
if it's run without limit, all cluster members inside containers can
go down at the same time.

In order to prevent that, we place policy-rc.d file that will simply
quit with 101 code `action forbidden by policy` on service restart
attempt.

Change-Id: I9140b7ab9f9266fcf4fe800e4610497f2324df4e

tasks/lxc_install_apt.yml

@@ -21,6 +21,16 @@
   tags:
     - lxc-apt-packages
 
+- name: Prevent lxc from starting on install
+  copy:
+    content: |
+      #!/bin/bash
+      exit 101
+    dest: "/usr/sbin/policy-rc.d"
+    mode: "0755"
+    backup: yes
+  changed_when: false
+
 - name: Install apt packages
   apt:
     pkg: "{{ lxc_hosts_distro_packages }}"
@@ -35,6 +45,12 @@
   tags:
     - lxc-apt-packages
 
+- name: Remove policy-rc now that the package install/upgrade is complete
+  file:
+    path: "/usr/sbin/policy-rc.d"
+    state: absent
+  changed_when: false
+
 - name: Drop irqbalance config
   template:
     src: "irqbalance.j2"