tuwunel hard-fails to start when /etc/resolv.conf has no nameserver
line (Failed to configure DNS resolver: no nameservers found in
config -> exit 1 -> systemd start-limit). The declarative
containers.hive-matrix generates its own resolv.conf via resolvconf
and, unlike agent containers whose resolv.conf is written by
hive-c0re's lifecycle, has no nameserver source -> it comes up empty
(just 'options edns0'). Defaulting network.enable on surfaced this:
the host DNS moved to the bridge dnsmasq but the container was never
pointed at it, so the homeserver could not boot, taking down matrix
for all agents.
Point the container at the hive resolver (the dnsmasq the network
module runs at bridgeIp) when the network module is enabled; the
container always shares the host netns (privateNetwork = false) so it
reaches bridgeIp whether or not isolateContainers is set. With the
network module off, inherit the host resolv.conf.
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