netplan: fix mtu if provided by network config for all rendered types

When network configuration for any interface defines maximum transmission
values (MTU) the netplan, eni and sysconfig renders will take into account
any device-level, or subnet-level mtu values.

When network configuration has conflicting device-level and ipv4 subnet
mtu values, the subnet-specific value is honored and a warning will be
logged about any ignored device-level setting.

LP: #1774666

1 files changed, 20 insertions, 1 deletions

diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index e13ca3ce..5ab61cf2 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -525,6 +525,7 @@ NETWORK_CONFIGS = {
             config:
               - type: 'physical'
                 name: 'iface0'
+                mtu: 8999
                 subnets:
                   - type: static
                     address: 192.168.14.2/24
@@ -660,8 +661,8 @@ iface eth0.101 inet static
     dns-nameservers 192.168.0.10 10.23.23.134
     dns-search barley.maas sacchromyces.maas brettanomyces.maas
     gateway 192.168.0.1
-    hwaddress aa:bb:cc:dd:ee:11
     mtu 1500
+    hwaddress aa:bb:cc:dd:ee:11
     vlan-raw-device eth0
     vlan_id 101
 
@@ -757,6 +758,7 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
                         id: 101
                         link: eth0
                         macaddress: aa:bb:cc:dd:ee:11
+                        mtu: 1500
                         nameservers:
                             addresses:
                             - 192.168.0.10
@@ -920,6 +922,8 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
                   mtu: 1500
                   subnets:
                     - type: static
+                      # When 'mtu' matches device-level mtu, no warnings
+                      mtu: 1500
                       address: 192.168.0.2/24
                       gateway: 192.168.0.1
                       dns_nameservers:
@@ -1028,6 +1032,7 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
               - type: bond
                 name: bond0
                 mac_address: "aa:bb:cc:dd:e8:ff"
+                mtu: 9000
                 bond_interfaces:
                   - bond0s0
                   - bond0s1
@@ -1070,6 +1075,7 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
                      interfaces:
                      - bond0s0
                      - bond0s1
+                     mtu: 9000
                      parameters:
                          mii-monitor-interval: 100
                          mode: active-backup
@@ -1157,6 +1163,7 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
         IPADDR1=192.168.1.2
         IPV6ADDR=2001:1::1/92
         IPV6INIT=yes
+        MTU=9000
         NETMASK=255.255.255.0
         NETMASK1=255.255.255.0
         NM_CONTROLLED=no
@@ -1203,6 +1210,7 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
                 name: en0
                 mac_address: "aa:bb:cc:dd:e8:00"
               - type: vlan
+                mtu: 2222
                 name: en0.99
                 vlan_link: en0
                 vlan_id: 99
@@ -1238,6 +1246,7 @@ pre-down route del -net 10.0.0.0 netmask 255.0.0.0 gw 11.0.0.1 metric 3 || true
                 IPV6ADDR=2001:1::bbbb/96
                 IPV6INIT=yes
                 IPV6_DEFAULTGW=2001:1::1
+                MTU=2222
                 NETMASK=255.255.255.0
                 NETMASK1=255.255.255.0
                 NM_CONTROLLED=no
@@ -1669,6 +1678,8 @@ iface eth1 inet dhcp
 
 class TestSysConfigRendering(CiTestCase):
 
+    with_logs = True
+
     scripts_dir = '/etc/sysconfig/network-scripts'
     header = ('# Created by cloud-init on instance boot automatically, '
               'do not edit.\n#\n')
@@ -1917,6 +1928,9 @@ USERCTL=no
         found = self._render_and_read(network_config=yaml.load(entry['yaml']))
         self._compare_files_to_expected(entry['expected_sysconfig'], found)
         self._assert_headers(found)
+        self.assertNotIn(
+            'WARNING: Network config: ignoring eth0.101 device-level mtu',
+            self.logs.getvalue())
 
     def test_small_config(self):
         entry = NETWORK_CONFIGS['small']
@@ -1929,6 +1943,10 @@ USERCTL=no
         found = self._render_and_read(network_config=yaml.load(entry['yaml']))
         self._compare_files_to_expected(entry['expected_sysconfig'], found)
         self._assert_headers(found)
+        expected_msg = (
+            'WARNING: Network config: ignoring iface0 device-level mtu:8999'
+            ' because ipv4 subnet-level mtu:9000 provided.')
+        self.assertIn(expected_msg, self.logs.getvalue())
 
     def test_dhcpv6_only_config(self):
         entry = NETWORK_CONFIGS['dhcpv6_only']
@@ -2410,6 +2428,7 @@ class TestNetplanRoundTrip(CiTestCase):
 
 
 class TestEniRoundTrip(CiTestCase):
+
     def _render_and_read(self, network_config=None, state=None, eni_path=None,
                          netrules_path=None, dir=None):
         if dir is None: