Bug#809166: networking.service does not prevent ifdown with network file systems

[Martin Pitt]

Hey Guus,

Guus Sliepen [2016-01-13 16:57 +0100]:
> Great. Who shall do the honors of writing a patch/bug report?

I filed https://bugs.debian.org/XXXXXX, thanks Michael for pointing
out conf.d/.

> > But independently of that: Do you actually think it is right that
> > "ifdown" on a manual interface without any "down" command downs it?
> > That isn't documented and hasn't happened until 0.8.4, and IMHO that's
> > overzealous and might break other setups too.
> 
> Uh, didn't we discuss that in #809169? Wasn't it already the default in
> Ubuntu?

It was, but as I said the check_network_file_systems() function
short-circuited this until recently, so interfaces were never really
downed on shutdown as soon as there was any remote file system. So
this (mis)design issue in ltsp and friends didn't really pop up until
now.

> Anyway, I'm not for or against it, but I was slightly convinced by the
> use case of lots of bonding slave interfaces, that it would make sense
> to have empty inet manual interfaces that did bring interfaces up or
> down. And that still is more convincing than the use case of LTSP doing
> the wrong thing.

From a clean slate POV I agree. I'm just a bit concerned about
breaking existing systems with that. I don't have a really strong
opinion, I just noticed that this change already caused regressions
with at least one package in Debian (ltsp) and two in Ubuntu (that and
open-isci).

That downing of interfaces is really only relevant for manual
operations, right? I can't think of anything bad that would happen if
a real interface is not downed during shutdown -- in fact, doing that
has no real benefit that I can see.

> But do we need backwards compatibility? If we get LTSP and open-iscsi
> fixed in unstable, is there still a problem somewhere?

There are more use cases/packages which set up a remote root fs;
initramfs-tools itself supports root-on-NFS, tcos, custom setups with
PXE boot, etc. I haven't searched for them or analyzed them all.

Thanks,

Martin
-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 819 bytes
Desc: Digital signature
URL: <http://alioth-lists.debian.net/pipermail/pkg-systemd-maintainers/attachments/20160113/206624ae/attachment-0002.sig>