Fix set-name/interface DNS bug

[akutz]

Proposed Commit Message

Fix set-name/interface DNS bug

This patch addresses an issue caused when the v2 network config
directive "set-name" was used in conjunction with interface-
specific DNS settings. The patch adds a test to validate the fix.

LP: #1946493

Additional Context

Please see kubernetes-sigs/image-builder#712 for more information.

Test Steps

Here is a patch that shows the update to a Cloud-Init test to validate the issue:

diff --git a/cloudinit/net/tests/test_network_state.py b/cloudinit/net/tests/test_network_state.py
index 84e8308a..c0aa78a0 100644
--- a/cloudinit/net/tests/test_network_state.py
+++ b/cloudinit/net/tests/test_network_state.py
@@ -52,6 +52,7 @@ network:
     eth1:
       match:
         macaddress: '66:77:88:99:00:11'
+      set-name: "eth2"
       nameservers:
         search: [foo.local, bar.local]
         addresses: [4.4.4.4]

And here is the test:

$ make clean_pyc && \
  PYTHONPATH="$(pwd)" \
  python3 -m pytest -v cloudinit/net/tests/test_network_state.py
====================================================================== test session starts ======================================================================
platform darwin -- Python 3.9.7, pytest-6.2.4, py-1.10.0, pluggy-0.13.1 -- /usr/local/opt/python@3.9/bin/python3.9
cachedir: .pytest_cache
rootdir: /Users/akutz/Projects/cloud-init, configfile: tox.ini
collected 10 items                                                                                                                                              

cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfig::test_empty_v1_config_gets_network_state PASSED                                    [ 10%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfig::test_empty_v2_config_gets_network_state PASSED                                    [ 20%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfig::test_missing_version_returns_none PASSED                                          [ 30%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfig::test_unknown_versions_returns_none PASSED                                         [ 40%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfig::test_valid_config_gets_network_state PASSED                                       [ 50%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfig::test_version_2_passes_self_as_config PASSED                                       [ 60%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseConfigV2::test_version_2_ignores_renderer_key PASSED                                      [ 70%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseNameservers::test_v1_nameservers_valid PASSED                                             [ 80%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseNameservers::test_v1_nameservers_invalid PASSED                                           [ 90%]
cloudinit/net/tests/test_network_state.py::TestNetworkStateParseNameservers::test_v2_nameservers FAILED                                                   [100%]

=========================================================================== FAILURES ============================================================================
_____________________________________________________ TestNetworkStateParseNameservers.test_v2_nameservers ______________________________________________________

self = <cloudinit.net.tests.test_network_state.TestNetworkStateParseNameservers object at 0x10a7db9d0>

    def test_v2_nameservers(self):
>       config = self._parse_network_state_from_config(V2_CONFIG_NAMESERVERS)

cloudinit/net/tests/test_network_state.py:139: 
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
cloudinit/net/tests/test_network_state.py:114: in _parse_network_state_from_config
    return network_state.parse_net_config_data(yaml['network'])
cloudinit/net/network_state.py:1074: in parse_net_config_data
    nsi.parse_config(skip_broken=skip_broken)
cloudinit/net/network_state.py:261: in parse_config
    self.parse_config_v2(skip_broken=skip_broken)
cloudinit/net/network_state.py:310: in parse_config_v2
    self._v2_common(command)
cloudinit/net/network_state.py:722: in _v2_common
    self._handle_individual_nameserver(name_cmd, iface)
cloudinit/net/network_state.py:91: in decorator
    return func(self, command, *args, **kwargs)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

self = <cloudinit.net.network_state.NetworkStateInterpreter object at 0x10a7e4f10>
command = {'address': ['4.4.4.4'], 'search': ['foo.local', 'bar.local'], 'type': 'nameserver'}, iface = 'eth1'

    @ensure_command_keys(['address'])
    def _handle_individual_nameserver(self, command, iface):
        _iface = self._network_state.get('interfaces')
        nameservers, search = self._parse_dns(command)
>       _iface[iface]['dns'] = {'nameservers': nameservers, 'search': search}
E       KeyError: 'eth1'

cloudinit/net/network_state.py:546: KeyError
----------------------------------------------------------------------- Captured log call -----------------------------------------------------------------------
2021-10-08 00:57:41 DEBUG     cloudinit.net.network_state:network_state.py:670 v2(ethernets) -> v1(physical):
{'type': 'physical', 'name': 'eth0', 'mac_address': '00:11:22:33:44:55', 'match': {'macaddress': '00:11:22:33:44:55'}}
2021-10-08 00:57:41 DEBUG     cloudinit.net.network_state:network_state.py:670 v2(ethernets) -> v1(physical):
{'type': 'physical', 'name': 'eth2', 'mac_address': '66:77:88:99:00:11', 'match': {'macaddress': '66:77:88:99:00:11'}}
2021-10-08 00:57:41 DEBUG     cloudinit.net.network_state:network_state.py:711 v2_common: handling config:
{'eth0': {'match': {'macaddress': '00:11:22:33:44:55'}, 'nameservers': {'search': ['spam.local', 'eggs.local'], 'addresses': ['8.8.8.8']}}, 'eth1': {'match': {'macaddress': '66:77:88:99:00:11'}, 'set-name': 'eth2', 'nameservers': {'search': ['foo.local', 'bar.local'], 'addresses': ['4.4.4.4']}}}
======================================================================= warnings summary ========================================================================
../../../../usr/local/lib/python3.9/site-packages/_pytest/config/__init__.py:1183
  /usr/local/lib/python3.9/site-packages/_pytest/config/__init__.py:1183: PytestDeprecationWarning: The --strict option is deprecated, use --strict-markers instead.
    self.issue_config_time_warning(

conftest.py:68
  /Users/akutz/Projects/cloud-init/conftest.py:68: PytestDeprecationWarning: @pytest.yield_fixture is deprecated.
  Use @pytest.fixture instead; they are the same.
    @pytest.yield_fixture(autouse=True)

conftest.py:169
  /Users/akutz/Projects/cloud-init/conftest.py:169: PytestDeprecationWarning: @pytest.yield_fixture is deprecated.
  Use @pytest.fixture instead; they are the same.
    def httpretty():

-- Docs: https://docs.pytest.org/en/stable/warnings.html
==================================================================== short test summary info ====================================================================
FAILED cloudinit/net/tests/test_network_state.py::TestNetworkStateParseNameservers::test_v2_nameservers - KeyError: 'eth1'
============================================================ 1 failed, 9 passed, 3 warnings in 0.60s ============================================================

Checklist:

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

[TheRealFalcon]

Thanks @akutz for the investigation and the fix!

[zawachte]

I think there might be a bug in a similar vein at ...
https://github.com/canonical/cloud-init/blob/main/cloudinit/net/networkd.py#L245

I applied this patch to a local setup and I got past this error but now I am hitting a KeyError here. Seems related to set-name as we are checking for a key name with what has been inputted into the "set-name" and that doesn't exist.

[TheRealFalcon]

@zawachte-msft , Can you create a bug at https://bugs.launchpad.net/cloud-init ? Including the full traceback and the network config used to trigger the error will allow us to reproduce and fix the issue.

[zawachte]

@pradipd just posted the bug: https://bugs.launchpad.net/cloud-init/+bug/1949407.