Add check for duplicate members in batch update

If a user requests a batch update of the members and includes the same
member twice in the body of the request, taskflow triggers an exception
(because of a duplicate Atom) and the load balancer is stuck in
PENDING_UPDATE. Now the API denies such calls and returns a
ValidationException if a member is updated more than once in the same
call.

Story 2010399
Task 46777

Change-Id: Ide2d5e637e5feb2dad43f952d5be1a195da1ae37
(cherry picked from commit d7b090702523cb07ae4aed0338f9e80fe30791a6)

octavia/api/v2/controllers/member.py

@@ -31,6 +31,7 @@ from octavia.common import data_models
 from octavia.common import exceptions
 from octavia.common import validate
 from octavia.db import prepare as db_prepare
+from octavia.i18n import _
 
 
 LOG = logging.getLogger(__name__)
@@ -365,12 +366,21 @@ class MembersController(MemberController):
             # Find members that are brand new or updated
             new_members = []
             updated_members = []
+            updated_member_uniques = set()
             for m in members:
-                if (m.address, m.protocol_port) not in old_member_uniques:
+                key = (m.address, m.protocol_port)
+                if key not in old_member_uniques:
                     validate.ip_not_reserved(m.address)
                     new_members.append(m)
                 else:
-                    m.id = old_member_uniques[(m.address, m.protocol_port)]
+                    m.id = old_member_uniques[key]
+                    if key in updated_member_uniques:
+                        LOG.error("Member %s is updated multiple times in "
+                                  "the same batch request.", m.id)
+                        raise exceptions.ValidationException(
+                            detail=_("Member must be updated only once in the "
+                                     "same request."))
+                    updated_member_uniques.add(key)
                     updated_members.append(m)
 
             # Find members that are deleted

octavia/tests/functional/api/v2/test_member.py

@@ -913,6 +913,38 @@ class TestMember(base.BaseAPITest):
             m_subnet_exists.assert_called_once_with(
                 member1['subnet_id'], context=mock.ANY)
 
+    @mock.patch('octavia.api.drivers.driver_factory.get_driver')
+    @mock.patch('octavia.api.drivers.utils.call_provider')
+    def test_update_members_member_duplicate(
+            self, mock_provider, mock_get_driver):
+        mock_driver = mock.MagicMock()
+        mock_driver.name = 'noop_driver'
+        mock_get_driver.return_value = mock_driver
+        subnet_id = uuidutils.generate_uuid()
+
+        member1 = {'address': '192.0.2.1', 'protocol_port': 80,
+                   'project_id': self.project_id, 'subnet_id': subnet_id}
+
+        req_dict = [member1]
+        body = {self.root_tag_list: req_dict}
+        path = self.MEMBERS_PATH.format(pool_id=self.pool_id)
+        self.put(path, body, status=202)
+
+        self.set_lb_status(self.lb_id)
+
+        # Same member (same address and protocol_port) updated twice in the
+        # same PUT request
+        member1 = {'address': '192.0.2.1', 'protocol_port': 80,
+                   'project_id': self.project_id, 'subnet_id': subnet_id,
+                   'name': 'member1'}
+        member2 = {'address': '192.0.2.1', 'protocol_port': 80,
+                   'project_id': self.project_id, 'subnet_id': subnet_id,
+                   'name': 'member2'}
+
+        req_dict = [member1, member2]
+        body = {self.root_tag_list: req_dict}
+        self.put(path, body, status=400)
+
     @mock.patch('octavia.api.drivers.driver_factory.get_driver')
     @mock.patch('octavia.api.drivers.utils.call_provider')
     def test_update_members_subnet_not_found(

releasenotes/notes/fix-error-with-duplicate-members-in-batch-update-610ffbbf949927d0.yaml

@@ -0,0 +1,10 @@
+---
+fixes:
+  - |
+    Added a validation step in the batch member API request that checks if a
+    member is included multiple times in the list of updated members, this
+    additional check prevents the load balancer from being stuck in
+    PENDING_UPDATE. Duplicate members in the batch member flow triggered an
+    exception in Taskflow.
+    The API now returns 400 (ValidationException) if a member is already
+    present in the body of the request.