Remove leftover OVN LB HM port upon deletion of a member

When a load balancer pool has a Health Monitor associated with it,
an OVN LB Health Monitor port is created for each backend member
subnet added.

When removing backend members, the OVN LB Health Monitor port is
cleaned up only if no more members are associated with the Health
Monitor pool. However, this assumption is incorrect. This patch
corrects this behavior by checking instead if there are more members
from the same subnet associated with the pool. It ensures that the
OVN LB Health Monitor port is deleted only when the last member from
the subnet is deleted. If the port is being used by another different
LB Health Monitor, `_clean_up_hm_port` will handle it.

Closes-Bug: #2062965
Change-Id: I4c35cc5c6af14bb208f4313bb86e3519df0a30fa

Author: fernandoroyosanchez

ovn_octavia_provider/helper.py

@@ -2189,20 +2189,32 @@ def _remove_member(self, member, ovn_lb, pool_key):
                 user_fault_string=msg,
                 operator_fault_string=msg)
 
+    def _members_in_subnet(self, ovn_lb, subnet_id):
+        for key, value in ovn_lb.external_ids.items():
+            if key.startswith(ovn_const.LB_EXT_IDS_POOL_PREFIX):
+                if value and len(value.split(',')) > 0:
+                    for m_info in value.split(','):
+                        mem_id, mem_ip_port, mem_subnet = m_info.split('_')[1:]
+                        if mem_subnet == subnet_id:
+                            return True
+        return False
+
     def member_delete(self, member):
         error_deleting_member = False
         try:
             pool_key, ovn_lb = self._find_ovn_lb_by_pool_id(
                 member[constants.POOL_ID])
 
-            pool_status = self._remove_member(member, ovn_lb, pool_key)
+            self._remove_member(member, ovn_lb, pool_key)
 
-            if ovn_lb.health_check and pool_status == constants.OFFLINE:
-                # NOTE(froyo): if the pool status is OFFLINE there are no more
-                # members. So we should ensure the hm-port is deleted if no
-                # more LB are using it. We need to do this call after the
-                # cleaning of the ip_port_mappings for the ovn LB.
-                self._clean_up_hm_port(member[constants.SUBNET_ID])
+            if ovn_lb.health_check:
+                mem_subnet = member[constants.SUBNET_ID]
+                if not self._members_in_subnet(ovn_lb, mem_subnet):
+                    # NOTE(froyo): if member is last member from the subnet
+                    # we should clean up the ovn-lb-hm-port.
+                    # We need to do this call after the cleaning of the
+                    # ip_port_mappings for the ovn LB.
+                    self._clean_up_hm_port(member[constants.SUBNET_ID])
         except Exception:
             LOG.exception(ovn_const.EXCEPTION_MSG, "deletion of member")
             error_deleting_member = True

ovn_octavia_provider/tests/unit/test_helper.py

@@ -2177,6 +2177,30 @@ def test_member_delete_hm(self, uhm, folbpi):
                                     self.member_address,
                                     delete=True)
 
+    @mock.patch.object(ovn_helper.OvnProviderHelper, '_find_ovn_lb_by_pool_id')
+    @mock.patch.object(ovn_helper.OvnProviderHelper, '_update_hm_member')
+    @mock.patch.object(ovn_helper.OvnProviderHelper, '_clean_up_hm_port')
+    def test_member_delete_keep_hm_port(self, del_hm_port, uhm, folbpi):
+        pool_key = 'pool_%s' % self.pool_id
+        member2_id = uuidutils.generate_uuid()
+        member2_address = '192.168.2.150'
+        member2_line = (
+            'member_%s_%s:%s_%s' %
+            (member2_id, member2_address,
+             self.member_port, self.member_subnet_id))
+        self.ovn_hm_lb.external_ids[pool_key] = ','.join([self.member_line,
+                                                          member2_line])
+        self.ovn_hm_lb.external_ids[ovn_const.OVN_MEMBER_STATUS_KEY] = \
+            '{"%s": "%s","%s": "%s"}' % (self.member_id, constants.ONLINE,
+                                         member2_id, constants.ONLINE)
+        folbpi.return_value = (pool_key, self.ovn_hm_lb)
+        self.helper.member_delete(self.member)
+        uhm.assert_called_once_with(self.ovn_hm_lb,
+                                    pool_key,
+                                    self.member_address,
+                                    delete=True)
+        del_hm_port.assert_not_called()
+
     def test_member_delete_not_found_in_pool(self):
         self.ovn_lb.external_ids.update({'pool_' + self.pool_id: ''})
         self.ovn_lb.external_ids[ovn_const.OVN_MEMBER_STATUS_KEY] = '{}'