attr_ops.verify_attributes() wrongly reject binding:host_id in _fixup_res_dict()

While testing puppet-openstack and Neutron with Debian packages (ie: running with Stretch and Queens), I had to use neutron-api using uwsgi, as /usr/bin/neutron-server would not work with Eventlet + Python 3 (which is famously broken). Therefore, I did a setup with uwsgi and running nova-rpc-server.

Then, I tried spawning an instance, then I got some issues in the rpc-server:

 [req-4b2c2379-78ef-437c-b08a-bd8b309fa0b0 - - - - -] Exception during message handling: ValueError: Unrecognized attribute(s) 'binding:host_id'
 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/neutron/plugins/common/utils.py", line 162, in _fixup_res_dict
     attr_ops.verify_attributes(res_dict)
   File "/usr/lib/python3/dist-packages/neutron_lib/api/attributes.py", line 200, in verify_attributes
     raise exc.HTTPBadRequest(msg)
 webob.exc.HTTPBadRequest: Unrecognized attribute(s) 'binding:host_id'

 During handling of the above exception, another exception occurred:

 Traceback (most recent call last):
   File "/usr/lib/python3/dist-packages/oslo_messaging/rpc/server.py", line 163, in _process_incoming
     res = self.dispatcher.dispatch(message)
   File "/usr/lib/python3/dist-packages/oslo_messaging/rpc/dispatcher.py", line 220, in dispatch
     return self._do_dispatch(endpoint, method, ctxt, args)
   File "/usr/lib/python3/dist-packages/oslo_messaging/rpc/dispatcher.py", line 190, in _do_dispatch
     result = func(ctxt, **new_args)
   File "/usr/lib/python3/dist-packages/oslo_messaging/rpc/server.py", line 226, in inner
     return func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/neutron/db/api.py", line 91, in wrapped
     setattr(e, '_RETRY_EXCEEDED', True)
   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
     self.force_reraise()
   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
     six.reraise(self.type_, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/six.py", line 693, in reraise
     raise value
   File "/usr/lib/python3/dist-packages/neutron/db/api.py", line 87, in wrapped
     return f(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/oslo_db/api.py", line 147, in wrapper
     ectxt.value = e.inner_exc
   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
     self.force_reraise()
   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
     six.reraise(self.type_, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/six.py", line 693, in reraise
     raise value
   File "/usr/lib/python3/dist-packages/oslo_db/api.py", line 135, in wrapper
     return f(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/neutron/db/api.py", line 126, in wrapped
     LOG.debug("Retry wrapper got retriable exception: %s", e)
   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 220, in __exit__
     self.force_reraise()
   File "/usr/lib/python3/dist-packages/oslo_utils/excutils.py", line 196, in force_reraise
     six.reraise(self.type_, self.value, self.tb)
   File "/usr/lib/python3/dist-packages/six.py", line 693, in reraise
     raise value
   File "/usr/lib/python3/dist-packages/neutron/db/api.py", line 122, in wrapped
     return f(*dup_args, **dup_kwargs)
   File "/usr/lib/python3/dist-packages/neutron/quota/resource_registry.py", line 99, in wrapper
     ret_val = f(_self, context, *args, **kwargs)
   File "/usr/lib/python3/dist-packages/neutron/api/rpc/handlers/dhcp_rpc.py", line 271, in create_dhcp_port
     return self._port_action(plugin, context, port, 'create_port')
   File "/usr/lib/python3/dist-packages/neutron/api/rpc/handlers/dhcp_rpc.py", line 98, in _port_action
     return p_utils.create_port(plugin, context, port)
   File "/usr/lib/python3/dist-packages/neutron/plugins/common/utils.py", line 189, in create_port
     check_allow_post=check_allow_post)
   File "/usr/lib/python3/dist-packages/neutron/plugins/common/utils.py", line 166, in _fixup_res_dict
     raise ValueError(e.detail)
 ValueError: Unrecognized attribute(s) 'binding:host_id'

FYI, the content of the res_dict variable before calling attr_ops.verify_attributes(res_dict) is as follow (I added a LOG.debug() to find out):

res_dict var: {'device_owner': 'network:dhcp', 'network_id': '5fa58f3a-3a72-4d5a-a781-dca20d882007', 'fixed_ips': [{'subnet_id': '85a0b153-fcd8-418d-90c2-7d0140431d61'}], 'mac_address': <neutron_lib.constants.Sentinel object at 0x7f4114ee65c0>, 'name': '', 'admin_state_up': True, 'binding:host_id': 'poi', 'device_id': 'dhcp6d2441eb-6701-5705-adb9-c31fa3421a1a-5fa58f3a-3a72-4d5a-a781-dca20d882007', 'tenant_id': 'be123aff43cd4699a0fd062dc0f898c6'}

As the binding:host_id looked valid to me (it's been there for years in Neutron), I figured out that the parameter validation code must have had something wrong, so I commented out the attr_ops.verify_attributes(res_dict) call. And without the check, everything worked again.

So, my guess is that there's either something wrong in the parameters when calling attr_ops.verify_attributes, or (less likely) there's an issue in neutron_lib/api/attributes.py.