Fix bug that resulted in an attempt to rename bonds or vlans.

When cloud-init ran in the init stage (after networking had come up).
A bug could occur where cloud-init would attempt and fail to rename
network devices that had "inherited" mac addresses.

The intent of apply_network_config_names was always to rename only
the devices that were "physical" per the network config.  (This would
include veth devices in a container).  The bug was in creating
the dictionary of interfaces by mac address.  If there were multiple
interfaces with the same mac address then renames could fail.
This situation was guaranteed to occur with bonds or vlans or other
devices that inherit their mac.

The solution is to change get_interfaces_by_mac to skip interfaces
that have an inherited mac.

Also drop the 'devs' argument to get_interfaces_by_mac.  It was
non-obvious what the result should be if a device in the input
list was filtered out. ie should the following have an entry for
bond0 or not.  get_interfaces_by_mac(devs=['bond0'])

LP: #1669860

1 files changed, 76 insertions, 0 deletions

diff --git a/tests/unittests/test_net.py b/tests/unittests/test_net.py
index bfd04ba0..9cc5e4ab 100644
--- a/tests/unittests/test_net.py
+++ b/tests/unittests/test_net.py
@@ -1461,6 +1461,82 @@ class TestNetRenderers(CiTestCase):
                           priority=['sysconfig', 'eni'])
 
 
+class TestGetInterfacesByMac(CiTestCase):
+    _data = {'devices': ['enp0s1', 'enp0s2', 'bond1', 'bridge1',
+                         'bridge1-nic', 'tun0'],
+             'bonds': ['bond1'],
+             'bridges': ['bridge1'],
+             'own_macs': ['enp0s1', 'enp0s2', 'bridge1-nic', 'bridge1'],
+             'macs': {'enp0s1': 'aa:aa:aa:aa:aa:01',
+                      'enp0s2': 'aa:aa:aa:aa:aa:02',
+                      'bond1': 'aa:aa:aa:aa:aa:01',
+                      'bridge1': 'aa:aa:aa:aa:aa:03',
+                      'bridge1-nic': 'aa:aa:aa:aa:aa:03',
+                      'tun0': None}}
+    data = {}
+
+    def _se_get_devicelist(self):
+        return self.data['devices']
+
+    def _se_get_interface_mac(self, name):
+        return self.data['macs'][name]
+
+    def _se_is_bridge(self, name):
+        return name in self.data['bridges']
+
+    def _se_interface_has_own_mac(self, name):
+        return name in self.data['own_macs']
+
+    def _mock_setup(self):
+        self.data = copy.deepcopy(self._data)
+        mocks = ('get_devicelist', 'get_interface_mac', 'is_bridge',
+                 'interface_has_own_mac')
+        self.mocks = {}
+        for n in mocks:
+            m = mock.patch('cloudinit.net.' + n,
+                           side_effect=getattr(self, '_se_' + n))
+            self.addCleanup(m.stop)
+            self.mocks[n] = m.start()
+
+    def test_raise_exception_on_duplicate_macs(self):
+        self._mock_setup()
+        self.data['macs']['bridge1-nic'] = self.data['macs']['enp0s1']
+        self.assertRaises(RuntimeError, net.get_interfaces_by_mac)
+
+    def test_excludes_any_without_mac_address(self):
+        self._mock_setup()
+        ret = net.get_interfaces_by_mac()
+        self.assertIn('tun0', self._se_get_devicelist())
+        self.assertNotIn('tun0', ret.values())
+
+    def test_excludes_stolen_macs(self):
+        self._mock_setup()
+        ret = net.get_interfaces_by_mac()
+        self.mocks['interface_has_own_mac'].assert_has_calls(
+            [mock.call('enp0s1'), mock.call('bond1')], any_order=True)
+        self.assertEqual(
+            {'aa:aa:aa:aa:aa:01': 'enp0s1', 'aa:aa:aa:aa:aa:02': 'enp0s2',
+             'aa:aa:aa:aa:aa:03': 'bridge1-nic'},
+            ret)
+
+    def test_excludes_bridges(self):
+        self._mock_setup()
+        # add a device 'b1', make all return they have their "own mac",
+        # set everything other than 'b1' to be a bridge.
+        # then expect b1 is the only thing left.
+        self.data['macs']['b1'] = 'aa:aa:aa:aa:aa:b1'
+        self.data['devices'].append('b1')
+        self.data['bonds'] = []
+        self.data['own_macs'] = self.data['devices']
+        self.data['bridges'] = [f for f in self.data['devices'] if f != "b1"]
+        ret = net.get_interfaces_by_mac()
+        self.assertEqual({'aa:aa:aa:aa:aa:b1': 'b1'}, ret)
+        self.mocks['is_bridge'].assert_has_calls(
+            [mock.call('bridge1'), mock.call('enp0s1'), mock.call('bond1'),
+             mock.call('b1')],
+            any_order=True)
+
+
 def _gzip_data(data):
     with io.BytesIO() as iobuf:
         gzfp = gzip.GzipFile(mode="wb", fileobj=iobuf)