Check mech driver connectivity during port binding

In [1] the concept of "connectivity" was introduced for the ML2 drivers.
This parameter defines the mech driver connectivity type (layer 2, layer
3 only or legacy - not defined).

The spec defined in the blueprint allows to spawn a VM with ports
without IP addresses. As commented in the Nova spec [2], those ports can
be bound only to "l2" drivers.

[1] https://review.opendev.org/#/c/645645/
[2] https://review.opendev.org/#/c/641670/

bp boot-vm-with-unaddressed-port
Related-Bug: #1821058

Change-Id: I438cbab43b45b5f7afc820b77fcf5a0e823d0eff

neutron/plugins/ml2/managers.py

@@ -826,10 +826,19 @@ class MechanismManager(stevedore.named.NamedExtensionManager):
                        'host': context.host})
             return False
 
+        drivers = self._check_drivers_connectivity(drivers, context)
+        if not drivers:
+            LOG.error("Port %(port)s does not have an IP address assigned and "
+                      "there are no driver with 'connectivity' = 'l2'. The "
+                      "port cannot be bound.",
+                      {'port': context.current['id']})
+            return False
+
         for driver in drivers:
             if not self._check_driver_to_bind(driver, segments_to_bind,
                                               context._binding_levels):
                 continue
+
             try:
                 context._prepare_to_bind(segments_to_bind)
                 driver.obj.bind_port(context)
@@ -1028,6 +1037,21 @@ class MechanismManager(stevedore.named.NamedExtensionManager):
                 return False
         return True
 
+    def _check_drivers_connectivity(self, drivers, port_context):
+        """If port does not have an IP address, driver connectivity must be l2
+
+        A port without an IP address can be bound only to a mech driver with
+        "connectivity" = "l2". "legacy" or "l3" (e.g.: Calico) drivers cannot
+        have a port bound without an IP allocated.
+        """
+        if port_context.current.get('fixed_ips'):
+            return drivers
+
+        return [d for d in drivers if
+                getattr(d.obj, 'vif_details', {}).get(
+                    portbindings.VIF_DETAILS_CONNECTIVITY) ==
+                portbindings.CONNECTIVITY_L2]
+
     def get_workers(self):
         workers = []
         for driver in self.ordered_mech_drivers:

neutron/tests/unit/plugins/ml2/_test_mech_agent.py

@@ -13,6 +13,8 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import copy
+
 from oslo_config import cfg
 from oslo_config import fixture as config_fixture
 
@@ -59,9 +61,14 @@ class FakePortContext(api.PortContext):
 
     @property
     def current(self):
-        return {'id': PORT_ID,
+        current_data = {'id': PORT_ID,
                         portbindings.VNIC_TYPE: self._bound_vnic_type,
                         portbindings.PROFILE: self._bound_profile}
+        ret_value = current_data
+        if self._original:
+            ret_value = copy.deepcopy(self.original)
+            ret_value.update(current_data)
+        return ret_value
 
     @property
     def original(self):

neutron/tests/unit/plugins/ml2/drivers/mech_fake_agent.py

@@ -45,7 +45,10 @@ class FakeAgentMechanismDriver(mech_agent.SimpleAgentMechanismDriverBase):
     def __init__(self):
         sg_enabled = securitygroups_rpc.is_firewall_enabled()
         vif_details = {portbindings.CAP_PORT_FILTER: sg_enabled,
-                       portbindings.OVS_HYBRID_PLUG: sg_enabled}
+                       portbindings.OVS_HYBRID_PLUG: sg_enabled,
+                       portbindings.VIF_DETAILS_CONNECTIVITY:
+                           portbindings.CONNECTIVITY_L2,
+                       }
         super(FakeAgentMechanismDriver, self).__init__(
             # NOTE(yamamoto): l2pop driver has a hardcoded list of
             # supported agent types.
@@ -64,3 +67,12 @@ class FakeAgentMechanismDriver(mech_agent.SimpleAgentMechanismDriverBase):
 
 class AnotherFakeAgentMechanismDriver(FakeAgentMechanismDriver):
     pass
+
+
+class FakeAgentMechanismDriverL3(FakeAgentMechanismDriver):
+    """ML2 mechanism driver for testing, with L3 connectivity only"""
+
+    def __init__(self):
+        super(FakeAgentMechanismDriverL3, self).__init__()
+        self.vif_details[portbindings.VIF_DETAILS_CONNECTIVITY] = (
+            portbindings.CONNECTIVITY_L3)

neutron/tests/unit/plugins/ml2/test_managers.py

@@ -41,9 +41,10 @@ class TestManagers(base.BaseTestCase):
                                   'network_type': 'vlan',
                                   'physical_network': 'public',
                                   api.SEGMENTATION_ID: 49}]
-        self.context = FakePortContext(None,
-                                       None,
-                                       self.segments_to_bind)
+        original_port = {'fixed_ips': [{'subnet_id': mock.ANY,
+                                        'ip_address': mock.ANY}]}
+        self.context = FakePortContext(None, None, self.segments_to_bind,
+                                       original=original_port)
         self.context._binding = mock.Mock()
         self.context._binding_levels = []
         self.context._new_bound_segment = self.segment_id
@@ -73,6 +74,26 @@ class TestManagers(base.BaseTestCase):
             manager._bind_port_level(self.context, 0, self.segments_to_bind)
         self.assertEqual(0, bind_port.call_count)
 
+    def _check_drivers_connectivity(self, agents):
+        cfg.CONF.set_override('mechanism_drivers', agents, group='ml2')
+        manager = managers.MechanismManager()
+        return (manager.ordered_mech_drivers,
+                manager._check_drivers_connectivity(
+                    manager.ordered_mech_drivers, self.context))
+
+    def test__check_drivers_connectivity(self):
+        self.assertEqual(*self._check_drivers_connectivity(['fake_agent']))
+
+    def test__check_drivers_connectivity_ip_less_port(self):
+        self.context._original['fixed_ips'] = []
+        self.assertEqual(*self._check_drivers_connectivity(['fake_agent']))
+
+    def test__check_drivers_connectivity_ip_less_port_l3_only_driver(self):
+        self.context._original['fixed_ips'] = []
+        self.assertEqual(
+            [],
+            self._check_drivers_connectivity(['fake_agent_l3'])[1])
+
     def test__infer_driver_from_allocation_positive(self):
         cfg.CONF.set_override(
             'mechanism_drivers', ['fake_agent'], group='ml2')

setup.cfg

@@ -95,6 +95,7 @@ neutron.ml2.mechanism_drivers =
     l2population = neutron.plugins.ml2.drivers.l2pop.mech_driver:L2populationMechanismDriver
     sriovnicswitch = neutron.plugins.ml2.drivers.mech_sriov.mech_driver.mech_driver:SriovNicSwitchMechanismDriver
     fake_agent = neutron.tests.unit.plugins.ml2.drivers.mech_fake_agent:FakeAgentMechanismDriver
+    fake_agent_l3 = neutron.tests.unit.plugins.ml2.drivers.mech_fake_agent:FakeAgentMechanismDriverL3
     another_fake_agent = neutron.tests.unit.plugins.ml2.drivers.mech_fake_agent:AnotherFakeAgentMechanismDriver
     faulty_agent = neutron.tests.unit.plugins.ml2.drivers.mech_faulty_agent:FaultyAgentMechanismDriver
 neutron.ml2.extension_drivers =