make barbican notification driver configurable

barbican alway use default notification driver (defalt '')
so we should change this value according to whether enable
notification

Change-Id: Ia17a64fe9bf31042369dec19f1f76b1ab8592288

ansible/roles/barbican/defaults/main.yml

@@ -145,6 +145,15 @@ barbican_ks_roles:
   - "{{ barbican_observer_role }}"
   - "{{ barbican_audit_role }}"
 
+####################
+# Notification
+####################
+barbican_notification_topics:
+  - name: notifications
+    enabled: "{{ enable_ceilometer | bool or enable_searchlight | bool }}"
+
+barbican_enabled_notification_topics: "{{ barbican_notification_topics | selectattr('enabled', 'equalto', true) | list }}"
+
 ####################
 # TLS
 ####################

ansible/roles/barbican/templates/barbican.conf.j2

@@ -67,6 +67,12 @@ memcached_servers = {% for host in groups['memcached'] %}{{ 'api' | kolla_addres
 
 [oslo_messaging_notifications]
 transport_url = {{ notify_transport_url }}
+{% if barbican_enabled_notification_topics %}
+driver = messagingv2
+topics = {{ barbican_enabled_notification_topics | map(attribute='name') | join(',') }}
+{% else %}
+driver = noop
+{% endif %}
 
 [oslo_middleware]
 enable_proxy_headers_parsing = True