Add variable to globally control notifications enablement

In order to be able to globally enable notification reporting for all services,
without an need to have ceilometer deployed or bunch of overrides for each
service, we add `oslomsg_notify_enabled` variable that aims to control
behaviour of enabled notifications.

Presence of ceilometer is still respected by default and being referenced.

Potential usecase are various billing panels that do rely on notifications
but do not require presence of Ceilometer.

Change-Id: Idd3bb9a0ab58307b6acced6dd60fce3adf17b138

defaults/main.yml

@@ -272,7 +272,7 @@ neutron_oslomsg_rpc_ssl_version: "{{ oslomsg_rpc_ssl_version | default('TLSv1_2'
 neutron_oslomsg_rpc_ssl_ca_file: "{{ oslomsg_rpc_ssl_ca_file | default('') }}"
 
 # Notify
-
+neutron_oslomsg_notify_configure: "{{ oslomsg_notify_configure | default(neutron_ceilometer_enabled) }}"
 neutron_oslomsg_notify_host_group: "{{ oslomsg_notify_host_group | default('rabbitmq_all') }}"
 neutron_oslomsg_notify_setup_host: >-
   {{ (neutron_oslomsg_notify_host_group in groups) | ternary(groups[neutron_oslomsg_notify_host_group][0], 'localhost') }}

tasks/main.yml

@@ -81,6 +81,7 @@
     _oslomsg_notify_vhost: "{{ neutron_oslomsg_notify_vhost }}"
     _oslomsg_notify_transport: "{{ neutron_oslomsg_notify_transport }}"
     _oslomsg_notify_policies: "{{ neutron_oslomsg_notify_policies }}"
+    _oslomsg_notify_configure: "{{ neutron_oslomsg_notify_configure }}"
   tags:
     - always
 

templates/neutron.conf.j2

@@ -254,7 +254,7 @@ rabbit_quorum_max_memory_bytes = {{ neutron_oslomsg_rabbit_quorum_max_memory_byt
 # Notifications
 [oslo_messaging_notifications]
 {% set notification_topics = [] %}
-{% if neutron_ceilometer_enabled %}
+{% if neutron_oslomsg_notify_configure %}
 {%   set _ = notification_topics.append('notifications') %}
 {% endif %}
 topics = {{ notification_topics | join(',') }}