Comment 2 for bug 2050200

just to summarise my investigations so far:

1) when a deployment is started the machine is powered on and the maas tries to allocate an IP for the interfaces with AUTO iP.
2) there might be some cases in which maas fails to allocate the IP and this is how we end up with no address in the Netplan config.

in order to reproduce this, you can force this function https://github.com/maas/maas/blob/deab73792a4fe839a2e84a926a6c728d510fc9ad/src/maasserver/models/node.py#L4626 to return like in the cases where no ip is allocated or the max retry limit is reached.

An hypothetic situation that can lead to this bug is if maas allocates 3 times an ip and they are already in use in the subnet by another device.

in order to triage this bug I think we need to understand if the customer is in a situazione like the one I just explained or similar.

we can statically try to find the bug looking at the code, but it might be time consuming and we might not find the issue of the customer.
IMO the best thing here is to add extra logging and extract an sos report when the issue is hit