Set MTU on nmstate bridge ports

Propagate the bridge MTU to its physical ports when using the
nmstate network engine.

Closes-Bug: #2164513

Change-Id: I05d3f386157b887d5f550104fef7c5e7ffeed923
Signed-off-by: Bartosz Bezak <bartosz@stackhpc.com>
(cherry picked from commit 4ac2b42)

Author: bbezak

kayobe/plugins/filter/nmstate.py

@@ -519,6 +519,8 @@ def get_iface(name):
             # <network>_port_type_<portname>.
             for port in br_ports or []:
                 port_iface = get_iface(port)
+                if mtu:
+                    port_iface.setdefault("mtu", mtu)
                 if "type" not in port_iface:
                     # Check for explicit type configuration
                     port_type = networks.net_attr(

kayobe/tests/unit/plugins/filter/test_nmstate.py

@@ -44,6 +44,7 @@ class TestNMStateFilter(unittest.TestCase):
         "net3_interface": "br0",
         "net3_bridge_ports": ['eth1'],
         "net3_bridge_stp": True,
+        "net3_mtu": 9000,
         # net4: bond on bond0 with slaves eth2 and eth3.
         "net4_interface": "bond0",
         "net4_bond_slaves": ['eth2', 'eth3'],
@@ -123,13 +124,15 @@ def test_nmstate_config_bridge(self):
         result = nmstate.nmstate_config(self.context, ["net3"])
         br_iface = next(i for i in result["interfaces"] if i["name"] == "br0")
         self.assertEqual(br_iface["type"], "linux-bridge")
+        self.assertEqual(br_iface["mtu"], 9000)
         self.assertEqual(br_iface["bridge"]["port"], [{"name": "eth1"}])
         self.assertTrue(br_iface["bridge"]["options"]["stp"]["enabled"])
 
         # eth1 should be present as ethernet
         eth1_iface = next(i for i in result["interfaces"]
                           if i["name"] == "eth1")
         self.assertEqual(eth1_iface["type"], "ethernet")
+        self.assertEqual(eth1_iface["mtu"], 9000)
 
     def test_nmstate_config_bond(self):
         result = nmstate.nmstate_config(self.context, ["net4"])