Azure: Treat _unset network configuration as if it were absent

When the Azure datasource persists all of its metadata to the
instance directory, it deliberately sets the self.network_config
value to be the sources.UNSET value. The goal is to ensure that
each time the system boots, fresh network configuration data is
fetched from the cloud platform so that any control plane changes
will take effect. When a VM is first created, there's no pickled
instance to restore, so self._network_config is None, resulting
in self.network_config() properly building a new config. Azure
suffered from LP: #1801364 which prevented ds from being stored
in obj.pkl in the instance directory, so subsequent reboots always
regenerated their network configuration.

Commit 0dc3a77f41f4544e4cb5a41637af7693410d4cdf introduced a
new bug in which self.network_config() assumed the
self._network_config value was either None or trustable; when
the config was unpickled, that value was _unset, thus breaking
the assumption.

LP: #1823084

1 files changed, 1 insertions, 1 deletions

diff --git a/cloudinit/sources/DataSourceAzure.py b/cloudinit/sources/DataSourceAzure.py
index d4230b3c..76b16616 100755
--- a/cloudinit/sources/DataSourceAzure.py
+++ b/cloudinit/sources/DataSourceAzure.py
@@ -688,7 +688,7 @@ class DataSourceAzure(sources.DataSource):
            2. Generate a fallback network config that does not include any of
               the blacklisted devices.
         """
-        if not self._network_config:
+        if not self._network_config or self._network_config == sources.UNSET:
             if self.ds_cfg.get('apply_network_config'):
                 nc_src = self._metadata_imds
             else: