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[Bug 1635593] [NEW] DBReferenceError while removing router (Cisco plugin case)

To: yahoo-eng-team@xxxxxxxxxxxxxxxxxxx
From: Oleksandr Kyrylchuk <albartash@xxxxxxxxx>
Date: Fri, 21 Oct 2016 10:33:19 -0000
Reply-to: Bug 1635593 <1635593@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx
Public bug reported:

Reproduced when trying to delete a heat stack contained a router.
Cloud: Mirantis Openstack 8.0 with Cisco ACI.

2016-09-19 14:57:57.353 35227 INFO neutron.wsgi [req-21a95707-6ce7-4c2a-9953-a74e8287f533 neutron 633eff38852d4b29a77b0967a4f190e5 - - -] 192.168.18.2 - - [19/Sep/2016 14:57:57] "GET /v2.0/ports.json?network_
id=6b0c8207-e57c-408f-a403-49ad9a4bde7a&device_owner=network%3Adhcp HTTP/1.1" 200 2065 0.270305
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource [req-169a5ca2-9d7f-4269-9be4-8affe22fb351 admin 03e77676e6634f848174068898bf06db - - -] delete failed
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource Traceback (most recent call last):
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/api/v2/resource.py", line 83, in resource
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     result = method(request=request, **args)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line 532, in delete
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return self._delete(request, id, **kwargs)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/oslo_db/api.py", line 146, in wrapper
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     ectxt.value = e.inner_exc
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 195, in __exit__
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/oslo_db/api.py", line 136, in wrapper
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return f(*args, **kwargs)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line 554, in _delete
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     obj_deleter(request.context, id, **kwargs)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/apic_ml2/neutron/services/l3_router/l3_apic.py", line 99, in delete_router
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     router_id)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/db/l3_db.py", line 1390, in delete_router
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     super(L3_NAT_db_mixin, self).delete_router(context, id)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/db/l3_db.py", line 455, in delete_router
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     context.session.delete(router)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 490, in __exit__
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.rollback()
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     compat.reraise(exc_type, exc_value, exc_tb)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 487, in __exit__
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.commit()
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 392, in commit
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self._prepare_impl()
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 372, in _prepare_impl
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.session.flush()
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 2004, in flush
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self._flush(objects)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 2122, in _flush
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     transaction.rollback(_capture_exception=True)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     compat.reraise(exc_type, exc_value, exc_tb)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 2086, in _flush
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     flush_context.execute()
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 373, in execute
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     rec.execute(self)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 561, in execute
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     uow
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/persistence.py", line 249, in delete_obj
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     cached_connections, mapper, table, delete)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/persistence.py", line 873, in _emit_delete_statements
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     c = connection.execute(statement, del_objects)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 914, in execute
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return meth(self, multiparams, params)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return connection._execute_clauseelement(self, multiparams, params)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1010, in _execute_clauseelement
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     compiled_sql, distilled_params
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1146, in _execute_context
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     context)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1337, in _handle_dbapi_exception
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     util.raise_from_cause(newraise, exc_info)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     reraise(type(exception), exception, tb=exc_tb)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1139, in _execute_context
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     context)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 450, in do_execute
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     cursor.execute(statement, parameters)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 219, in execute
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.errorhandler(self, exc, value)
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 38, in defaulterrorhandler
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     raise errorvalue
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource DBReferenceError: (_mysql_exceptions.IntegrityError) (1451, 'Cannot delete or update a parent row: a foreign key constraint fails (`neutron`.`cisco_ml2_apic_contracts`, CONSTRAINT `cisco_ml2_apic_contracts_ibfk_1` FOREIGN KEY (`router_id`) REFERENCES `routers` (`id`))') [SQL: u'DELETE FROM routers WHERE routers.id = %s'] [parameters: ('0b5865d6-b498-46af-be47-337495b09ae7',)]
2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource
2016-09-19 14:57:58.176 35267 INFO neutron.wsgi [req-169a5ca2-9d7f-4269-9be4-8affe22fb351 admin 03e77676e6634f848174068898bf06db - - -] 192.168.18.42 - - [19/Sep/2016 14:57:58] "DELETE /v2.0/routers/0b5865d6-
b498-46af-be47-337495b09ae7.json HTTP/1.1" 500 378 4.105855
2016-09-19 14:57:58.583 35188 INFO neutron.wsgi [-] (35188) accepted ('192.168.18.2', 55871)
2016-09-19 14:57:58.848 35188 INFO neutron.wsgi [req-dae982af-6fd2-4a06-a068-915c12c100d7 neutron 633eff38852d4b29a77b0967a4f190e5 - - -] 192.168.18.2 - - [19/Sep/2016 14:57:58] "GET /v2.0/networks.json?id=88385617-ecc7-4af2-bf73-f95d2dc31d10 HTTP/1.1" 200 642 0.263556
2016-09-19 14:57:59.081 35227 INFO neutron.wsgi [-] (35227) accepted ('192.168.18.2', 55925)
2016-09-19 14:57:59.343 35227 INFO neutron.wsgi [req-a1c79851-ae20-4318-8a20-a909fa76f5fa neutron 633eff38852d4b29a77b0967a4f190e5 - - -] 192.168.18.2 - - [19/Sep/2016 14:57:59] "GET /v2.0/subnets.json?id=81c7ebc3-895f-4927-bedb-00e064691c94 HTTP/1.1" 200 743 0.261777

** Affects: neutron
     Importance: Undecided
         Status: New

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https://bugs.launchpad.net/bugs/1635593

Title:
  DBReferenceError while removing router (Cisco plugin case)

Status in neutron:
  New

Bug description:
  Reproduced when trying to delete a heat stack contained a router.
  Cloud: Mirantis Openstack 8.0 with Cisco ACI.

  2016-09-19 14:57:57.353 35227 INFO neutron.wsgi [req-21a95707-6ce7-4c2a-9953-a74e8287f533 neutron 633eff38852d4b29a77b0967a4f190e5 - - -] 192.168.18.2 - - [19/Sep/2016 14:57:57] "GET /v2.0/ports.json?network_
  id=6b0c8207-e57c-408f-a403-49ad9a4bde7a&device_owner=network%3Adhcp HTTP/1.1" 200 2065 0.270305
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource [req-169a5ca2-9d7f-4269-9be4-8affe22fb351 admin 03e77676e6634f848174068898bf06db - - -] delete failed
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource Traceback (most recent call last):
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/api/v2/resource.py", line 83, in resource
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     result = method(request=request, **args)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line 532, in delete
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return self._delete(request, id, **kwargs)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/oslo_db/api.py", line 146, in wrapper
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     ectxt.value = e.inner_exc
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/oslo_utils/excutils.py", line 195, in __exit__
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     six.reraise(self.type_, self.value, self.tb)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/oslo_db/api.py", line 136, in wrapper
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return f(*args, **kwargs)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/api/v2/base.py", line 554, in _delete
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     obj_deleter(request.context, id, **kwargs)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/apic_ml2/neutron/services/l3_router/l3_apic.py", line 99, in delete_router
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     router_id)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/db/l3_db.py", line 1390, in delete_router
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     super(L3_NAT_db_mixin, self).delete_router(context, id)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/neutron/db/l3_db.py", line 455, in delete_router
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     context.session.delete(router)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 490, in __exit__
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.rollback()
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     compat.reraise(exc_type, exc_value, exc_tb)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 487, in __exit__
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.commit()
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 392, in commit
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self._prepare_impl()
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 372, in _prepare_impl
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.session.flush()
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 2004, in flush
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self._flush(objects)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 2122, in _flush
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     transaction.rollback(_capture_exception=True)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/langhelpers.py", line 60, in __exit__
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     compat.reraise(exc_type, exc_value, exc_tb)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/session.py", line 2086, in _flush
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     flush_context.execute()
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 373, in execute
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     rec.execute(self)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/unitofwork.py", line 561, in execute
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     uow
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/persistence.py", line 249, in delete_obj
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     cached_connections, mapper, table, delete)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/orm/persistence.py", line 873, in _emit_delete_statements
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     c = connection.execute(statement, del_objects)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 914, in execute
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return meth(self, multiparams, params)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/sql/elements.py", line 323, in _execute_on_connection
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     return connection._execute_clauseelement(self, multiparams, params)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1010, in _execute_clauseelement
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     compiled_sql, distilled_params
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1146, in _execute_context
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     context)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1337, in _handle_dbapi_exception
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     util.raise_from_cause(newraise, exc_info)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/util/compat.py", line 199, in raise_from_cause
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     reraise(type(exception), exception, tb=exc_tb)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/base.py", line 1139, in _execute_context
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     context)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/sqlalchemy/engine/default.py", line 450, in do_execute
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     cursor.execute(statement, parameters)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/MySQLdb/cursors.py", line 219, in execute
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     self.errorhandler(self, exc, value)
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource   File "/usr/lib/python2.7/dist-packages/MySQLdb/connections.py", line 38, in defaulterrorhandler
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource     raise errorvalue
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource DBReferenceError: (_mysql_exceptions.IntegrityError) (1451, 'Cannot delete or update a parent row: a foreign key constraint fails (`neutron`.`cisco_ml2_apic_contracts`, CONSTRAINT `cisco_ml2_apic_contracts_ibfk_1` FOREIGN KEY (`router_id`) REFERENCES `routers` (`id`))') [SQL: u'DELETE FROM routers WHERE routers.id = %s'] [parameters: ('0b5865d6-b498-46af-be47-337495b09ae7',)]
  2016-09-19 14:57:58.162 35267 ERROR neutron.api.v2.resource
  2016-09-19 14:57:58.176 35267 INFO neutron.wsgi [req-169a5ca2-9d7f-4269-9be4-8affe22fb351 admin 03e77676e6634f848174068898bf06db - - -] 192.168.18.42 - - [19/Sep/2016 14:57:58] "DELETE /v2.0/routers/0b5865d6-
  b498-46af-be47-337495b09ae7.json HTTP/1.1" 500 378 4.105855
  2016-09-19 14:57:58.583 35188 INFO neutron.wsgi [-] (35188) accepted ('192.168.18.2', 55871)
  2016-09-19 14:57:58.848 35188 INFO neutron.wsgi [req-dae982af-6fd2-4a06-a068-915c12c100d7 neutron 633eff38852d4b29a77b0967a4f190e5 - - -] 192.168.18.2 - - [19/Sep/2016 14:57:58] "GET /v2.0/networks.json?id=88385617-ecc7-4af2-bf73-f95d2dc31d10 HTTP/1.1" 200 642 0.263556
  2016-09-19 14:57:59.081 35227 INFO neutron.wsgi [-] (35227) accepted ('192.168.18.2', 55925)
  2016-09-19 14:57:59.343 35227 INFO neutron.wsgi [req-a1c79851-ae20-4318-8a20-a909fa76f5fa neutron 633eff38852d4b29a77b0967a4f190e5 - - -] 192.168.18.2 - - [19/Sep/2016 14:57:59] "GET /v2.0/subnets.json?id=81c7ebc3-895f-4927-bedb-00e064691c94 HTTP/1.1" 200 743 0.261777

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Follow ups

[Bug 1635593] Re: DBReferenceError while removing router (Cisco plugin case)
From: Launchpad Bug Tracker, 2016-12-25