systemd-resolved and single-label DNS entries

[Jeff Layton <jlayton@kernel.org>]

I'm hitting a problem with NFS testing on kdevops guests. Recently when
I bring up a guest, it's unable to resolve the name of the NFS server
via DNS.

When guests are brought up, kdevops currently registers their names in
DNS without any domain. For instance, the hostname "kdevops-nfsd" gets
a hostname in DNS of "kdevops-nfsd." (with no domain).

The DNS server on the KVM host will resolve a name like that just fine,
but systemd-resolved will not forward requests for those names via DNS.
It will only attempt a LLMNR request (which gets no response). I think
this is by design:

    https://github.com/systemd/systemd/issues/2514

I'm not sure of the best way to fix this. I can see a couple of
options:

1/ We could create a bogus domain name (.example.com? .kdevops?) and
put it in all of the search paths for the guests.

2/ Alternately, maybe we could go all-in on LLMNR and get that working.
I have zero experience with that, so I'm not sure what it entails. This
might also be problematic for guests that have no LLMNR lookup
capability.

-- 
Jeff Layton <jlayton@kernel.org>