net/netplan: use ipv6-mtu key for specifying ipv6 mtu values

netplan introduced an 'info' subcommand which emits yaml describing
implemented features that indicate new or changed fields and values
in the yaml that it accepts. Previously, cloud-init emitted the key
'mtu6' for ipv6 MTU values. This is not correct and netplan will
fail to parse these values. Netplan as of 0.98 supports both the
info subcommand and the ipv6-mtu key.

This branch modifies the netplan renderer to collect the netplan
info output into a 'features' property which is a list of available
feature flags which the renderer can use to modify its output. If
the command is not available, no feature flags are set and
cloud-init will render IPv6 MTU values just as MTU for the subnet.

1 files changed, 25 insertions, 2 deletions

diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index d2201998..21604b12 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -996,8 +996,8 @@ NETWORK_CONFIGS = {
                         addresses:
                         - 192.168.14.2/24
                         - 2001:1::1/64
+                        ipv6-mtu: 1500
                         mtu: 9000
-                        mtu6: 1500
         """).rstrip(' '),
         'yaml': textwrap.dedent("""\
             version: 1
@@ -3585,7 +3585,9 @@ class TestNetplanPostcommands(CiTestCase):
 
     @mock.patch.object(netplan.Renderer, '_netplan_generate')
     @mock.patch.object(netplan.Renderer, '_net_setup_link')
-    def test_netplan_render_calls_postcmds(self, mock_netplan_generate,
+    @mock.patch('cloudinit.util.subp')
+    def test_netplan_render_calls_postcmds(self, mock_subp,
+                                           mock_netplan_generate,
                                            mock_net_setup_link):
         tmp_dir = self.tmp_dir()
         ns = network_state.parse_net_config_data(self.mycfg,
@@ -3597,6 +3599,7 @@ class TestNetplanPostcommands(CiTestCase):
         render_target = 'netplan.yaml'
         renderer = netplan.Renderer(
             {'netplan_path': render_target, 'postcmds': True})
+        mock_subp.side_effect = iter([util.ProcessExecutionError])
         renderer.render_network_state(ns, target=render_dir)
 
         mock_netplan_generate.assert_called_with(run=True)
@@ -3619,7 +3622,13 @@ class TestNetplanPostcommands(CiTestCase):
         render_target = 'netplan.yaml'
         renderer = netplan.Renderer(
             {'netplan_path': render_target, 'postcmds': True})
+        mock_subp.side_effect = iter([
+            util.ProcessExecutionError,
+            ('', ''),
+            ('', ''),
+        ])
         expected = [
+            mock.call(['netplan', 'info'], capture=True),
             mock.call(['netplan', 'generate'], capture=True),
             mock.call(['udevadm', 'test-builtin', 'net_setup_link',
                        '/sys/class/net/lo'], capture=True),
@@ -3875,6 +3884,20 @@ class TestReadInitramfsConfig(CiTestCase):
 
 
 class TestNetplanRoundTrip(CiTestCase):
+
+    NETPLAN_INFO_OUT = textwrap.dedent("""
+    netplan.io:
+      features:
+        - dhcp-use-domains
+        - ipv6-mtu
+      website: https://netplan.io/
+    """)
+
+    def setUp(self):
+        super(TestNetplanRoundTrip, self).setUp()
+        self.add_patch('cloudinit.net.netplan.util.subp', 'm_subp')
+        self.m_subp.return_value = (self.NETPLAN_INFO_OUT, '')
+
     def _render_and_read(self, network_config=None, state=None,
                          netplan_path=None, target=None):
         if target is None: