Enable deployers to force update cell mappings

Add variable nova_cell_force_update to enable deployers to ensure that
role execution will also update cell mappings whenever that is needed.
For instance, it could be password rotation or intention to update MySQL
address.

Change-Id: I5b99d58a5c4d27a363306361544c5d80759483fd

defaults/main.yml

@@ -128,6 +128,7 @@ nova_api_db_connection_recycle_time: "{{ openstack_db_connection_recycle_time |
 ## DB Cells
 nova_cell0_database: "nova_cell0"
 nova_cell1_name: "cell1"
+nova_cell_force_update: False
 
 ## Oslo Messaging
 

releasenotes/notes/force_update_cell-efd821d2a5fa7ef0.yaml

@@ -0,0 +1,7 @@
+---
+features:
+  - |
+    Added variable ``nova_cell_force_update`` that can be set to
+    True during runtime to force update cell records.
+    This might be useful in case of password rotation for DB users
+    for cell0 or any other changes in connection configuration.

tasks/nova_db_setup.yml

@@ -61,7 +61,8 @@
   changed_when: false
   when:
     - _cell0_record | length > 0
-    - ('ssl_verify_cert' not in _cell0_record[0] and nova_galera_use_ssl) or
+    - nova_cell_force_update or
+      ('ssl_verify_cert' not in _cell0_record[0] and nova_galera_use_ssl) or
       ('ssl_verify_cert' in _cell0_record[0] and not nova_galera_use_ssl)
 
 - name: Synchronize the nova DB schema
@@ -105,7 +106,8 @@
   changed_when: false
   when:
     - _cell1_record | length > 0
-    - (nova_oslomsg_rpc_port ~ '/' ~ _nova_oslomsg_rpc_vhost_conf) not in _cell1_record[0]
+    - nova_cell_force_update or
+      (nova_oslomsg_rpc_port ~ '/' ~ _nova_oslomsg_rpc_vhost_conf) not in _cell1_record[0]
 
 # The nova-status upgrade check command is typically run after upgrading the
 # controller services to new code, but is also OK to run for a greenfield