Do not access DB when it is in maintenance mode.

If the database is in maintenace mode do not attempt to access
it.

Depends-On: I5d8ed7d3935db5568c50f8d585e37a4d0cc6914f
Change-Id: I7d5b7a20573b38d12b1ead708ee446472f21e9f8

hooks/nova_cc_hooks.py

@@ -398,6 +398,12 @@ def db_changed():
         hookenv.log('shared-db relation incomplete. Peer not ready?')
         return
 
+    if ch_utils.is_db_maintenance_mode():
+        hookenv.log(
+            'Database maintenance mode, aborting hook.',
+            level=hookenv.DEBUG)
+        return
+
     CONFIGS.write_all()
     leader_init_db_if_ready()
     # db init for cells v2 requires amqp transport_url and db connections to

unit_tests/test_nova_cc_hooks.py

@@ -40,6 +40,7 @@ TO_PATCH = [
     'charmhelpers.contrib.openstack.utils.configure_installation_source',
     'charmhelpers.contrib.openstack.utils.config_value_changed',
     'charmhelpers.contrib.openstack.utils.is_unit_paused_set',
+    'charmhelpers.contrib.openstack.utils.is_db_maintenance_mode',
     'charmhelpers.contrib.openstack.utils.openstack_upgrade_available',
     'charmhelpers.contrib.openstack.utils.os_release',
     'charmhelpers.core.hookenv.charm_dir',
@@ -105,6 +106,7 @@ class NovaCCHooksTests(CharmTestCase):
         self.charm_dir.return_value = '/var/lib/juju/charms/nova/charm'
         self.ns_query.return_value = None
         self.is_unit_paused_set.return_value = False
+        self.is_db_maintenance_mode.return_value = False
         # disable hardening for unit tests
         harden._DISABLE_HARDENING_FOR_UNIT_TEST = True