Run nova api_db sync before db sync

Backport: Stein, Rocky

Since cells v2 was introduced, nova operators must run two commands to
migrate the database schemas of nova's databases - nova-manage api_db
sync and nova-manage db sync. It is necessary to run them in this order,
since the db sync may depend on schema changes made to the api
database in the api_db sync. Executing the db sync first may fail,
for example with the following seen in a Queens to Rocky upgrade:

    nova-manage db sync
    ERROR: Could not access cell0.
    Has the nova_api database been created?
    Has the nova_cell0 database been created?
    Has "nova-manage api_db sync" been run?
    Has "nova-manage cell_v2 map_cell0" been run?
    Is [api_database]/connection set in nova.conf?
    Is the cell0 database connection URL correct?
    Error: (pymysql.err.InternalError) (1054, u"Unknown column
            'cell_mappings.disabled' in 'field list'") [SQL: u'SELECT
    cell_mappings.created_at AS cell_mappings_created_at,
    cell_mappings.updated_at AS cell_mappings_updated_at,
    cell_mappings.id AS cell_mappings_id, cell_mappings.uuid AS
    cell_mappings_uuid, cell_mappings.name AS cell_mappings_name,
    cell_mappings.transport_url AS cell_mappings_transport_url,
    cell_mappings.database_connection AS
    cell_mappings_database_connection, cell_mappings.disabled AS
    cell_mappings_disabled \nFROM cell_mappings \nWHERE
    cell_mappings.uuid = %(uuid_1)s \n LIMIT %(param_1)s'] [parameters:
    {u'uuid_1': '00000000-0000-0000-0000-000000000000', u'param_1': 1}]
    (Background on this error at: http://sqlalche.me/e/2j85)

Despite this error, the command actually exits zero, so kolla does not notice
the failure.

This change reorders these two commands to run the api_db sync before the db
sync.

Change-Id: I0514c02aaee1a413a7979c3a426e0484df839861
Closes-Bug: #1832860
(cherry picked from commit 84a0710)

Author: markgoddard

docker/nova/nova-api/extend_start.sh

@@ -3,15 +3,15 @@
 # Bootstrap and exit if KOLLA_BOOTSTRAP variable is set. This catches all cases
 # of the KOLLA_BOOTSTRAP variable being set, including empty.
 if [[ "${!KOLLA_BOOTSTRAP[@]}" ]]; then
-    nova-manage db sync
     nova-manage api_db sync
+    nova-manage db sync
     nova-manage db online_data_migrations
     exit 0
 fi
 
 if [[ "${!KOLLA_UPGRADE[@]}" ]]; then
-    nova-manage db sync
     nova-manage api_db sync
+    nova-manage db sync
     exit 0
 fi