Comment 0 for bug 1979678

We are using the nocloud datasource to bootstrap VMs into ganeti via https://github.com/neicnordic/ganeti-os-nocloud but in the past few weeks, network on new VMs has been broken.

In `/var/lib/cloud/seed/nocloud/network-config` I have, for example:

```
version: 2
ethernets:
  eth0:
    match: {macaddress: 'aa:00:00:45:6a:15'}
    addresses:
      - '10.20.12.9/16'
    gateway4: '10.20.0.1'
    nameservers:
        addresses:
          - '10.22.1.1'
```

When the instance bootstraps, I see this error in `/var/log/cloud-init-output.log`:

```
Cloud-init v. 22.2-0ubuntu1~20.04.2 running 'init-local' at Thu, 23 Jun 2022 17:29:24 +0000. Up 9.69 seconds.
2022-06-23 17:29:25,617 - util.py[WARNING]: failed stage init-local
failed run of stage init-local
------------------------------------------------------------
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 738, in status_wrapper
    ret = functor(name, args)
  File "/usr/lib/python3/dist-packages/cloudinit/cmd/main.py", line 410, in main_init
    init.apply_network_config(bring_up=bring_up_interfaces)
  File "/usr/lib/python3/dist-packages/cloudinit/stages.py", line 937, in apply_network_config
    return self.distro.apply_network_config(
  File "/usr/lib/python3/dist-packages/cloudinit/distros/__init__.py", line 231, in apply_network_config
    network_state = parse_net_config_data(netconfig)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 1056, in parse_net_config_data
    nsi.parse_config(skip_broken=skip_broken)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 278, in parse_config
    self.parse_config_v2(skip_broken=skip_broken)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 328, in parse_config_v2
    self._v2_common(command)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 782, in _v2_common
    self._handle_individual_nameserver(name_cmd, iface)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 110, in decorator
    return func(self, command, *args, **kwargs)
  File "/usr/lib/python3/dist-packages/cloudinit/net/network_state.py", line 570, in _handle_individual_nameserver
    _iface[iface]["dns"] = {"nameservers": nameservers, "search": search}
KeyError: 'eth0'
------------------------------------------------------------
```

Some searching brought me to a similar circumstance at https://bugs.launchpad.net/cloud-init/+bug/1946493