fix: use name of interface instead of relying on idx

src/maasserver/models/bmc.py

@@ -1107,8 +1107,16 @@ def _assign_interfaces(
         # configuration.
         created_interfaces = []
         for idx, discovered_nic in enumerate(discovered_machine.interfaces):
+            # For the scenario of lxd, it returns the interfaces ordered
+            # alphabetically likely due to it being written in Go. So we need
+            # to properly match the correct name here instead of relying on
+            # order.
+            # When coming from virsh, the interfaces do not have a meaningful
+            # name. So we fall back to the previous behavior (which might
+            # be even correct in that scenario.)
+            name = discovered_nic.name or interface_names[idx]
             interface = self._create_interface(
-                discovered_nic, machine, name=interface_names[idx]
+                discovered_nic, machine, name=name
             )
             created_interfaces.append(interface)
             if discovered_nic.boot:

src/provisioningserver/drivers/pod/__init__.py

@@ -180,6 +180,7 @@ class DiscoveredMachineInterface:
     attach_name = attr.ib(
         converter=converter_obj(str, optional=True), default=None
     )
+    name = attr.ib(converter=converter_obj(str, optional=True), default=None)
 
 
 @attr.s

src/provisioningserver/drivers/pod/lxd.py

@@ -728,6 +728,7 @@ def _get_discovered_interface(name, device, boot):
                 boot=boot,
                 attach_type=attach_type,
                 attach_name=attach_name,
+                name=name,
             )
 
         extra_block_devices = 0

src/provisioningserver/drivers/pod/tests/test_lxd.py

@@ -995,6 +995,7 @@ def test_get_discovered_machine(self):
                 boot=True,
                 attach_type=InterfaceAttachType.BRIDGE,
                 attach_name="lxdbr0",
+                name="eth0",
             ),
         )
         self.assertEqual(
@@ -1006,6 +1007,7 @@ def test_get_discovered_machine(self):
                 boot=False,
                 attach_type=InterfaceAttachType.BRIDGE,
                 attach_name="br1",
+                name="eth1",
             ),
         )
         self.assertEqual(
@@ -1017,6 +1019,7 @@ def test_get_discovered_machine(self):
                 boot=False,
                 attach_type=InterfaceAttachType.MACVLAN,
                 attach_name="eno2",
+                name="eth2",
             ),
         )
         self.assertEqual(
@@ -1028,6 +1031,7 @@ def test_get_discovered_machine(self):
                 boot=False,
                 attach_type=InterfaceAttachType.SRIOV,
                 attach_name="eno3",
+                name="eth3",
             ),
         )
         self.assertEqual(
@@ -1039,6 +1043,7 @@ def test_get_discovered_machine(self):
                 boot=False,
                 attach_type=InterfaceAttachType.SRIOV,
                 attach_name="eno3",
+                name="eth4",
             ),
         )
         self.assertEqual(
@@ -1050,6 +1055,7 @@ def test_get_discovered_machine(self):
                 boot=False,
                 attach_type=InterfaceAttachType.SRIOV,
                 attach_name="eno3",
+                name="eth5",
             ),
         )
         self.assertEqual([], discovered_machine.tags)