On Sun, 11 Feb 2024 at 13:53:56 -0800, Benjamin Kaduk wrote:
> On Sat, Feb 10, 2024 at 01:33:15PM +0100, Johannes Schauer Marin Rodrigues
> wrote:
> > there as a binNMU "Rebuild to sync binNMU versions" for krb5 and that
> > failed for arm64, armel and ppc64el:
> >
> > https://buildd.debian.org/status/package.php?p=krb5
> >
> > The error logs look very similar:
> > *** Output of last command:
> > Can't resolve hostname arm-conova-03
>
> This is due more to the build environment than the test suite per se.
...
> In short, the test suite, as for the protocol itself, assumes that it can
> resolve the server's hostname to an IP address
It might be relevant that according to #972151, arm-conova-03 (and
perhaps other *-conova-* buildds?) is IPv6-only, with no IPv4 addresses
or routes other than loopback (not even via NAT).
I believe there is consensus that we consider "localhost resolves to
127.0.0.1" to be a reasonable thing to demand from all buildds as part
of the build-essential interface.
I am unsure whether there is consensus that "the result of gethostname()
resolves to some address of the local machine" is also a reasonable
thing to demand from all buildds as part of build-essential: /etc/hosts
typically makes this true, but is not *guaranteed* to do so. On Linux,
packages can ensure that it happens by build-depending on
libnss-myhostname [linux-any], if necessary.
However, even with both of those, if the krb5 test suite (or protocol)
is resolving the local hostname with AF_INET (IPv4-only), and with either
AI_ADDRCONFIG or NULL hints, then that will not yield any results on
an IPv6-only system for the reasons discussed in #952740 and related
bug reports.
A workaround is to resolve with AF_UNSPEC, which currently disregards
AI_ADDRCONFIG, but that is, itself, arguably a bug (#854301).
If I'm understanding the krb5 issue correctly, the version of this in krb5
is more troublesome than the related issues seen in the GLib test suite,
because the GLib test suite would be happy with localhost always being
resolvable to 127.0.0.1 (as requested in #801362), but the krb5 test suite
wants to be able to resolve the local host name as well (so
resolving #801362 would not be enough).
smcv
