Update default cell_v2 cell when it already exists

nova-manage cell_v2 create_cell just uses a dumb string comparison to detect
when a cell already exists. If there is a slight difference (e.g ordering of
params in the db uri query string) it can result in duplicate cells.

With this patch we should detect that the default cell already exists and
update it to use the current transport_url/database_connection instead of
attempting to create a new cell.

Change-Id: If6a32e87b19cb0edf683144367701a115657ad0a
Closes-bug: 1718912

docker/services/nova-api.yaml

@@ -169,6 +169,18 @@ outputs:
             done
             echo "(cellv2) Running host discovery..."
             su nova -s /bin/bash -c "/usr/bin/nova-manage cell_v2 discover_hosts --verbose"
+        nova_api_ensure_default_cell.sh:
+          mode: "0700"
+          content: |
+            #!/bin/bash
+            DEFID=$(nova-manage cell_v2 list_cells | sed -e '1,3d' -e '$d' | awk -F ' *| *' '$2 == "default" {print $4}')
+            if [ "$DEFID" ]; then
+              echo "(cellv2) Updating default cell_v2 cell $DEFID"
+              su nova -s /bin/bash -c "/usr/bin/nova-manage cell_v2 update_cell --cell_uuid $DEFID --name=default"
+            else
+              echo "(cellv2) Creating default cell_v2 cell"
+              su nova -s /bin/bash -c "/usr/bin/nova-manage cell_v2 create_cell --name=default"
+            fi
       docker_config:
         step_2:
           get_attr: [NovaApiLogging, docker_config, step_2]
@@ -187,9 +199,6 @@ outputs:
                   - /var/lib/config-data/nova/etc/my.cnf.d/tripleo.cnf:/etc/my.cnf.d/tripleo.cnf:ro
                   - /var/lib/config-data/nova/etc/nova/:/etc/nova/:ro
             command: "/usr/bin/bootstrap_host_exec nova_api su nova -s /bin/bash -c '/usr/bin/nova-manage api_db sync'"
-          # FIXME: we probably want to wait on the 'cell_v2 update' in order for this
-          # to be capable of upgrading a baremetal setup. This is to ensure the name
-          # of the cell is 'default'
           nova_api_map_cell0:
             start_order: 1
             image: *nova_api_image
@@ -198,18 +207,21 @@ outputs:
             user: root
             volumes: *nova_api_bootstrap_volumes
             command: "/usr/bin/bootstrap_host_exec nova_api su nova -s /bin/bash -c '/usr/bin/nova-manage cell_v2 map_cell0'"
-          nova_api_create_default_cell:
+          nova_api_ensure_default_cell:
             start_order: 2
             image: *nova_api_image
             net: host
             detach: false
-            volumes: *nova_api_bootstrap_volumes
-            # NOTE: allowing the exit code 2 is a dirty way of making
-            # this idempotent (if the resource already exists a conflict
-            # is raised)
-            exit_codes: [0,2]
+            volumes:
+              list_concat:
+                - *nova_api_bootstrap_volumes
+                -
+                  - /var/lib/config-data/nova/etc/my.cnf.d/tripleo.cnf:/etc/my.cnf.d/tripleo.cnf:ro
+                  - /var/lib/config-data/nova/etc/nova/:/etc/nova/:ro
+                  - /var/log/containers/nova:/var/log/nova
+                  - /var/lib/docker-config-scripts/nova_api_ensure_default_cell.sh:/nova_api_ensure_default_cell.sh:ro
             user: root
-            command: "/usr/bin/bootstrap_host_exec nova_api su nova -s /bin/bash -c '/usr/bin/nova-manage cell_v2 create_cell --name=default'"
+            command: "/usr/bin/bootstrap_host_exec nova_api /nova_api_ensure_default_cell.sh"
           nova_db_sync:
             start_order: 3
             image: *nova_api_image