Disable unused console services

This is best practise to only deploy one remote access method at a
time. This patch ensures only one of the nova-novncproxy, nova-spicehtml5proxy
or nova-serialproxy services is enabled and running.

This is a necessary step for upgrades from stein to train which use
the OSA defaults, where the console type has will switch from spice to novnc.
The old nova-spicehtml5proxy service continually fail and restart, running
from the stein venv.

The service fails because the nova config option use_journal is now
set to true. Nova-spicehtml5proxy service consumes this config and tries to
use journal logging which is not possible in the stein venv due to a 
missing systemd-python package. This dependancy was only added in Train.

Change-Id: I420a95caf7981034f6549c2b6f8296839d9ed65f

tasks/nova_install.yml

@@ -72,6 +72,23 @@
     - nova-novnc-console
     - nova-spice-console
 
+- name: Populate service facts
+  service_facts:
+
+- name: Disable existing services for any unused console types
+  systemd:
+    name: "{{ item.service }}"
+    enabled: no
+    state: stopped
+  when: item.service in ansible_facts.services and item.type != nova_console_type
+  loop:
+    - service: "nova-novncproxy.service"
+      type: "novnc"
+    - service: "nova-spicehtml5proxy.service"
+      type: "spice"
+    - service: "nova-serialproxy.service"
+      type: "serialconsole"
+
 - name: Initialise the upgrade facts
   ini_file:
     dest: "/etc/ansible/facts.d/openstack_ansible.fact"