Enable notification from Keystone when Barbican is enabled

Barbican, especially the barbican-keystone-listener service, consumes
notifications from Keystone so that secrets associated with deleted
users are purged. This change ensures notification is enabled in
Keystone when Barbican is enabled to use that feature properly.

Closes-Bug: #1956400
Change-Id: I9322cd2a2f274daba1d02d5bf98e5abbca795df0

deployment/keystone/keystone-container-puppet.yaml

@@ -182,6 +182,12 @@ parameters:
     type: comma_delimited_list
     default: 'noop'
     description: Driver or drivers to handle sending notifications.
+  KeystoneNotificationDriver:
+    type: comma_delimited_list
+    default: []
+    description: |
+      Driver or drivers to handle sending notifications. This parameter is
+      specific to Keystone.
   KeystoneEnableDBPurge:
     default: true
     description: |
@@ -464,6 +470,7 @@ conditions:
   unique_last_password_count_set: {not: {equals: [{get_param: KeystoneUniqueLastPasswordCount}, '']}}
   cors_allowed_origin_set: {not: {equals : [{get_param: KeystoneCorsAllowedOrigin}, '']}}
   admin_token_set: {not: {equals: [{get_param: AdminToken}, '']}}
+  keystone_notification_driver_set: {not: {equals: [{get_param: KeystoneNotificationDriver}, []]}}
 
 outputs:
   role_data:
@@ -525,7 +532,11 @@ outputs:
               - {get_param: KeystoneDebug}
               - true
               - {get_param: Debug }
-            keystone::notification_driver: {get_param: NotificationDriver}
+            keystone::notification_driver:
+              if:
+              - keystone_notification_driver_set
+              - {get_param: KeystoneNotificationDriver}
+              - {get_param: NotificationDriver}
             keystone::notification_format: {get_param: KeystoneNotificationFormat}
             tripleo::profile::base::keystone::extra_notification_topics: {get_param: KeystoneNotificationTopics}
             keystone_enable_db_purge: {get_param: KeystoneEnableDBPurge}

environments/services-baremetal/barbican.yaml

@@ -2,3 +2,6 @@
 # Barbican with the default secret store backend.
 resource_registry:
   OS::TripleO::Services::BarbicanApi: ../../deployment/barbican/barbican-api-container-puppet.yaml
+
+parameter_defaults:
+  KeystoneNotificationDriver: messagingv2

environments/services/barbican.yaml

@@ -2,3 +2,6 @@
 # Barbican with the default secret store backend.
 resource_registry:
   OS::TripleO::Services::BarbicanApi: ../../deployment/barbican/barbican-api-container-puppet.yaml
+
+parameter_defaults:
+  KeystoneNotificationDriver: messagingv2

releasenotes/notes/keystone-notification-driver-0c71165430eb57ef.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    The new ``KeystoneNotificationDriver`` parameter has been added.
+    This parameter overrides the global ``NotificationDriver`` parameter and
+    allows customizing notification driver only in Keystone, which is required
+    to use notification listner function in Barbican.