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: Ib654a82fd91cd73c6ab5c178d87d054d8717ce4f

hooks/heat_relations.py

@@ -65,6 +65,7 @@ from charmhelpers.contrib.openstack.utils import (
     series_upgrade_complete,
     series_upgrade_prepare,
     sync_db_with_multi_ipv6_addresses,
+    is_db_maintenance_mode,
 )
 
 from charmhelpers.contrib.openstack.ha.utils import (
@@ -252,6 +253,9 @@ def db_joined():
 @hooks.hook('shared-db-relation-changed')
 @restart_on_change(restart_map())
 def db_changed():
+    if is_db_maintenance_mode():
+        log('Database maintenance mode, aborting hook.')
+        return
     if 'shared-db' not in CONFIGS.complete_contexts():
         log('shared-db relation incomplete. Peer not ready?')
         return

unit_tests/test_heat_relations.py

@@ -81,6 +81,7 @@ TO_PATCH = [
     'relation_get',
     'local_unit',
     'get_relation_ip',
+    'is_db_maintenance_mode',
 ]
 
 
@@ -187,6 +188,7 @@ class HeatRelationTests(CharmTestCase):
         self.assertTrue(self.get_relation_ip.called)
 
     def _shared_db_test(self, configs):
+        self.is_db_maintenance_mode.return_value = False
         self.relation_get.return_value = 'heat/0 heat/1'
         self.local_unit.return_value = 'heat/0'
         configs.complete_contexts = MagicMock()
@@ -203,6 +205,7 @@ class HeatRelationTests(CharmTestCase):
 
     @patch.object(relations, 'CONFIGS')
     def test_db_changed_missing_relation_data(self, configs):
+        self.is_db_maintenance_mode.return_value = False
         configs.complete_contexts = MagicMock()
         configs.complete_contexts.return_value = []
         relations.db_changed()