Detect port-resource-request-groups neutron API extension

The new neutron API extension signals the format change of the
resource_request field of the port. This patch only adds functions to
detect the existence of such extension. Later patches will adapt Nova
for the new format.

Depends-On: https://review.opendev.org/c/openstack/neutron-lib/+/803905

Change-Id: I4b400d499b9f594798f2da6d16f21204371a9f42
blueprint: qos-minimum-guaranteed-packet-rate

nova/network/constants.py

@@ -29,6 +29,7 @@ MIGRATING_ATTR = 'migrating_to'
 L3_NETWORK_TYPES = ['vxlan', 'gre', 'geneve']
 ALLOCATION = 'allocation'
 RESOURCE_REQUEST = 'resource_request'
+REQUEST_GROUPS = 'request_groups'
 SEGMENT = 'Segment'
 NUMA_POLICY = 'numa_affinity_policy'
 RESOURCE_REQUEST_GROUPS_EXTENSION = "Port Resource Request Groups"

nova/network/neutron.py

@@ -995,6 +995,13 @@ class API:
 
         return requests_and_created_ports
 
+    def _has_resource_request(self, context, port, neutron):
+        resource_request = port.get(constants.RESOURCE_REQUEST) or {}
+        if self._has_extended_resource_request_extension(context, neutron):
+            return bool(resource_request.get(constants.REQUEST_GROUPS, []))
+        else:
+            return bool(resource_request)
+
     def allocate_for_instance(self, context, instance,
                               requested_networks,
                               security_groups=None, bind_host_id=None,
@@ -1270,6 +1277,14 @@ class API:
         self._refresh_neutron_extensions_cache(context, neutron=neutron)
         return constants.SEGMENT in self.extensions
 
+    # TODO(gibi): Remove all branches where this is False after Neutron made
+    # the this extension mandatory. In Xena this extension will be optional to
+    # support the scenario where Neutron upgraded first. So Neutron can mark
+    # this mandatory earliest in Yoga.
+    def _has_extended_resource_request_extension(self, context, neutron=None):
+        self._refresh_neutron_extensions_cache(context, neutron=neutron)
+        return constants.RESOURCE_REQUEST_GROUPS_EXTENSION in self.extensions
+
     def supports_port_binding_extension(self, context):
         """This is a simple check to see if the neutron "binding-extended"
         extension exists and is enabled.

nova/tests/unit/network/test_neutron.py

@@ -6571,6 +6571,71 @@ class TestAPI(TestAPIBase):
         mock_debug.assert_called_with('No PCI device found for request %s',
                                       uuids.pci_request_id, instance=instance)
 
+    @mock.patch(
+        'nova.network.neutron.API.'
+        '_has_extended_resource_request_extension')
+    def test__has_resource_request(self, mock_has_extended_res_req):
+        # Old format, resource_request in None. That is Neutron current
+        # behavior if the port has no QoS policy associated.
+        mock_has_extended_res_req.return_value = False
+        port_no_res_req = {"resource_request": None}
+        self.assertFalse(self.api._has_resource_request(
+            self.context, port_no_res_req, neutron=None)
+        )
+        # Old format, there is resource_request key but no resource is
+        # requested. We should never get this from Neutron today but we
+        # actually get it if there are QoS policy assigned to the port but
+        # there is no rule in that policy requesting resources.
+        port_old_empty_res_req = {"resource_request": {}}
+        self.assertFalse(self.api._has_resource_request(
+            self.context, port_old_empty_res_req, neutron=None)
+        )
+        # Old format, and the port has resource request.
+        port_old_res_req = {
+            "resource_request": {
+                "resources": {
+                    "NET_BW_IGR_KILOBIT_PER_SEC": 1000,
+                }
+            }
+        }
+        self.assertTrue(self.api._has_resource_request(
+            self.context, port_old_res_req, neutron=None)
+        )
+        # New format tests are starting here
+        mock_has_extended_res_req.return_value = True
+        # New format, port has no QoS policy assigned
+        port_no_res_req = {"resource_request": None}
+        self.assertFalse(self.api._has_resource_request(
+            self.context, port_no_res_req, neutron=None)
+        )
+        # New format, port has a resource_request key but no resource is
+        # requested. Neutron never sends this, it sends None instead. We keep
+        # this here for completeness as the code actually handle this properly.
+        port_new_empty_res_req = {
+            "resource_request": {
+                "request_groups": []
+            }
+        }
+        self.assertFalse(self.api._has_resource_request(
+            self.context, port_new_empty_res_req, neutron=None)
+        )
+        # New format, port has a resource request
+        port_new_res_req = {
+            "resource_request": {
+                "request_groups": [
+                    {
+                        "resources": {
+                            "NET_KILOPACKET_PER_SEC": 1000
+                        }
+                    },
+                ],
+                "same_subtree": [],
+            }
+        }
+        self.assertTrue(self.api._has_resource_request(
+            self.context, port_new_res_req, neutron=None)
+        )
+
 
 class TestAPIModuleMethods(test.NoDBTestCase):