sources/azure: remove unnecessary hostname bounce

[cjp256]

Thanks to [1], the hostname is set prior to network bring-up.

The Azure data source has been bouncing the hostname during
setup(), occurring after the hostname has already been
properly configured.

Note that this doesn't prevent leaking the image's hostname
during Azure's _get_data() when it brings up ephemeral DHCP.
However, as are not guaranteed to have the hostname metadata
available from a truly "local" source, this behavior is to
be expected unless we disable send host-name from dhclient
config.

133ad2c

Signed-off-by: Chris Patterson cpatterson@microsoft.com

Additional Context

This behavior be seen easily enough by launching an Ubuntu 20.04 VM on Azure.

grep -i hostname /var/log/cloud-init.log

2021-12-09 17:16:25,706 - DataSourceAzure.py[DEBUG]: Hostname retrieved from IMDS: cpatterson-u20-x1
2021-12-09 17:16:26,093 - cc_set_hostname.py[DEBUG]: Setting the hostname to cpatterson-u20-x1 (cpatterson-u20-x1)
2021-12-09 17:16:26,093 - util.py[DEBUG]: Reading from /etc/hostname (quiet=False)
2021-12-09 17:16:26,093 - util.py[DEBUG]: Read 7 bytes from /etc/hostname
2021-12-09 17:16:26,093 - util.py[DEBUG]: Writing to /etc/hostname - wb: [644] 18 bytes
2021-12-09 17:16:26,093 - init.py[DEBUG]: Non-persistently setting the system hostname to cpatterson-u20-x1
2021-12-09 17:16:26,094 - subp.py[DEBUG]: Running command ['hostname', 'cpatterson-u20-x1'] with allowed return codes [0] (shell=False, capture=True)
2021-12-09 17:16:26,096 - atomic_helper.py[DEBUG]: Atomically writing to file /var/lib/cloud/data/set-hostname (via temporary file /var/lib/cloud/data/tmp8t_8f9ws) - w: [644] 67 bytes/chars
2021-12-09 17:16:28,658 - handlers.py[DEBUG]: start: azure-ds/bounce_network_with_azure_hostname: bounce_network_with_azure_hostname
2021-12-09 17:16:28,658 - DataSourceAzure.py[DEBUG]: Hostname in metadata is cpatterson-u20-x1
2021-12-09 17:16:28,658 - handlers.py[DEBUG]: start: azure-ds/temporary_hostname: temporary_hostname
2021-12-09 17:16:28,658 - handlers.py[DEBUG]: finish: azure-ds/temporary_hostname: SUCCESS: temporary_hostname
2021-12-09 17:16:28,658 - subp.py[DEBUG]: Running command ('hostname',) with allowed return codes [0] (shell=False, capture=True)
2021-12-09 17:16:28,662 - handlers.py[DEBUG]: finish: azure-ds/bounce_network_with_azure_hostname: SUCCESS: bounce_network_with_azure_hostname

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!