On Sat, Mar 16, 2024 at 10:02:31AM -0700, Junio C Hamano wrote:

Jeff King [off-list ref] writes:

quoted

Do we need to define "hostname" in more detail here? Specifically, I'm
wondering whether the result will be a FQDN or not (i.e., the output of
"hostname" vs "hostname -f"). Looking at the code I think it will just
be the short name returned. That's probably OK, but it may be worth
documenting.

That was my first reaction but there are places where "hostname"
already gives a name that is not "short" at all, without being
invoked with "-f".

Thanks, that was the vague buzzing in the back of my head that led to
my first comment. It has been a while since I've dealt with this, but I
think in some circles it is a holy war akin to tabs vs spaces. A quick
search shows I am not alone:

  https://serverfault.com/questions/331936/setting-the-hostname-fqdn-or-short-name

So I think we probably need to say something like:

  Depending on how your system is configured, the hostname used for
  matching may be short (e.g., "myhost") or a fully qualified domain
  name ("myhost.example.com").

I think the most honest answer we can give in the documentation is
that we use what gethostname() [*] gives.

That is honest, but I wonder if it is very useful to most users, as they
cannot easily see what it returns. It's tempting to give an extra note
like this tacked on to what I said above:

  You can run the hostname(1) tool to see which hostname your system
  uses.

But I'm not sure that it is available everywhere (especially Windows).
I guess we could provide "git config --show-hostname-for-includes" or
something, but that feels like overkill.

Maybe just the "Depending..." note is enough, and people who are
interested in hostname conditionals hopefully know enough to dig further
on their system. What I think we want to avoid is saying nothing, and
then somebody tries "foo.example.com", finds that it doesn't work, and
gets confused with no hints about why.

I guess yet another alternative is to try to qualify the name ourselves
using getaddrinfo(), either unconditionally or if the hostname doesn't
contain a ".". That may involve a DNS lookup, though (if your hostname
isn't in /etc/hosts).

-Peff