Bug#1097699: systemd-resolved defaulting to hostname 'linux' on trixie

[Philip Stewart]

Package: systemd-resolved
Version: 257.3-1

Hello,

On trixie, during the startup of systemd-resolved I observe the info
message: "Defaulting to hostname 'linux'."

/etc/hostname is populated and the correct hostname is returned by
hostnamectl and hostname

Attempting to set the hostname (with either hostnamectl or hostname)
results in systemd-resolved emitting the warning message: "Failed to
determine the local hostname and LLMNR/mDNS names, ignoring: Invalid
argument"

I prefer to set ReadEtcHosts=no, but observe the behaviour above with
ReadEtcHosts set to either yes or no. However, without suitable
entries for the local hostname in /etc/hosts, or if ReadEtcHosts=no,
systemd-resolved does not synthesize records for the local hostname,
and so queries for the local hostname are not found, oddly (to me at
least!) causing sudo to emit a warning upon use that it is unable to
resolve the host.

I do not observe the same behaviour on any of my bookworm machines
using systemd-resolved.

Thank you,
Phil