net: exclude OVS internal interfaces in get_interfaces (#829)

`get_interfaces` is used to in two ways, broadly: firstly, to determine
the available interfaces when converting cloud network configuration
formats to cloud-init's network configuration formats; and, secondly, to
ensure that any interfaces which are specified in network configuration
are (a) available, and (b) named correctly.  The first of these is
unaffected by this commit, as no clouds support Open vSwitch
configuration in their network configuration formats.

For the second, we check that MAC addresses of physical devices are
unique.  In some OVS configurations, there are OVS-created devices which
have duplicate MAC addresses, either with each other or with physical
devices.  As these interfaces are created by OVS, we can be confident
that (a) they will be available when appropriate, and (b) that OVS will
name them correctly.  As such, this commit excludes any OVS-internal
interfaces from the set of interfaces returned by `get_interfaces`.

LP: #1912844

1 files changed, 8 insertions, 0 deletions

diff --git a/tests/unittests/test_datasource/test_configdrive.py b/tests/unittests/test_datasource/test_configdrive.py
index 6f830cc6..2e2b7847 100644
--- a/tests/unittests/test_datasource/test_configdrive.py
+++ b/tests/unittests/test_datasource/test_configdrive.py
@@ -494,6 +494,10 @@ class TestConfigDriveDataSource(CiTestCase):
         self.assertEqual('config-disk (/dev/anything)', cfg_ds.subplatform)
 
 
+@mock.patch(
+    "cloudinit.net.is_openvswitch_internal_interface",
+    mock.Mock(return_value=False)
+)
 class TestNetJson(CiTestCase):
     def setUp(self):
         super(TestNetJson, self).setUp()
@@ -654,6 +658,10 @@ class TestNetJson(CiTestCase):
             self.assertEqual(out_data, conv_data)
 
 
+@mock.patch(
+    "cloudinit.net.is_openvswitch_internal_interface",
+    mock.Mock(return_value=False)
+)
 class TestConvertNetworkData(CiTestCase):
 
     with_logs = True