LBaaS: add delete_health_monitor() to driver API

Currently there is create_health_monitor() in the driver API so
a driver may create an object on device but there is no delete_health_monitor()
and monitor objects will remain on device forever.
Driver should at least call plugin to delete a db object.

Fixes bug 1198996

Change-Id: Idcdaea0636e01381064983d8de5bfe3936357fb9

neutron/services/loadbalancer/drivers/abstract_driver.py

@@ -120,6 +120,13 @@ class LoadBalancerAbstractDriver(object):
                               pool_id):
         pass
 
+    @abc.abstractmethod
+    def delete_health_monitor(self, context, health_monitor):
+        """Driver may call the code below in order to delete the monitor.
+        self.plugin._delete_db_health_monitor(context, health_monitor["id"])
+        """
+        pass
+
     @abc.abstractmethod
     def create_pool_health_monitor(self, context,
                                    health_monitor,

neutron/services/loadbalancer/drivers/haproxy/plugin_driver.py

@@ -357,5 +357,8 @@ class HaproxyOnHostPluginDriver(abstract_driver.LoadBalancerAbstractDriver):
     def create_health_monitor(self, context, health_monitor):
         pass
 
+    def delete_health_monitor(self, context, health_monitor):
+        self.plugin._delete_db_health_monitor(context, health_monitor["id"])
+
     def stats(self, context, pool_id):
         pass

neutron/services/loadbalancer/drivers/noop/noop_driver.py

@@ -89,6 +89,10 @@ class NoopLbaaSDriver(abstract_driver.LoadBalancerAbstractDriver):
                               pool_association):
         pass
 
+    @log.log
+    def delete_health_monitor(self, context, health_monitor):
+        self.plugin._delete_db_health_monitor(context, health_monitor["id"])
+
     @log.log
     def create_pool_health_monitor(self, context,
                                    health_monitor, pool_id):

neutron/services/loadbalancer/plugin.py

@@ -185,6 +185,9 @@ class LoadBalancerPlugin(loadbalancer_db.LoadBalancerPluginDb,
                                                                    hm_id,
                                                                    pool_id)
 
+    def _delete_db_health_monitor(self, context, id):
+        super(LoadBalancerPlugin, self).delete_health_monitor(context, id)
+
     def delete_health_monitor(self, context, id):
         with context.session.begin(subtransactions=True):
             hm = self.get_health_monitor(context, id)
@@ -195,6 +198,7 @@ class LoadBalancerPlugin(loadbalancer_db.LoadBalancerPluginDb,
                 self.driver.delete_pool_health_monitor(context,
                                                        hm,
                                                        assoc['pool_id'])
+            self.driver.delete_health_monitor(context, hm)
 
     def create_pool_health_monitor(self, context, health_monitor, pool_id):
         retval = super(LoadBalancerPlugin, self).create_pool_health_monitor(

neutron/tests/unit/db/loadbalancer/test_db_loadbalancer.py

@@ -859,10 +859,18 @@ class TestLoadBalancer(LoadBalancerPluginDbTestCase):
 
     def test_delete_healthmonitor(self):
         with self.health_monitor(no_delete=True) as monitor:
+            ctx = context.get_admin_context()
+            qry = ctx.session.query(ldb.HealthMonitor)
+            qry = qry.filter_by(id=monitor['health_monitor']['id'])
+            self.assertIsNotNone(qry.first())
+
             req = self.new_delete_request('health_monitors',
                                           monitor['health_monitor']['id'])
             res = req.get_response(self.ext_api)
             self.assertEqual(res.status_int, 204)
+            qry = ctx.session.query(ldb.HealthMonitor)
+            qry = qry.filter_by(id=monitor['health_monitor']['id'])
+            self.assertIsNone(qry.first())
 
     def test_delete_healthmonitor_cascade_deletion_of_associations(self):
         with self.health_monitor(type='HTTP', no_delete=True) as monitor: