Saturday, 9 May 2015

Re: Proposal: enable stateless persistant network interface names

Hello Robie,

Robie Basak [2015-05-08 13:49 +0100]:
> Hi Martin,
>
> On Fri, May 08, 2015 at 07:27:39AM +0200, Martin Pitt wrote:
> > Proposal
> > --------
> > I propose to retire [mac], i. e. drop
> > /lib/udev/rules.d/75-persistent-net-generator.rules and enable
> > [ifnames] by default on all platforms (client, server, touch, snappy),
> > and stop installing biosdevname on server.
> >
> > This will provide the new stable interface names for all new
> > installations, stop the different handling of server/client, work with
> > system-image, and stops the woes cloud providers have with Ubuntu's
> > [mac].
> >
> > For upgrades: As we don't know what refers to existing stable network
> > names, we can't ever safely remove a generated
> > /etc/udev/rules.d/70-persistent-net.rules or uninstall biosdevname. So
> > when we do the above, names on existing installations will *not*
> > change (as 70-persistent-net.rules trumps [biosdevname] trumps [ifnames]).
>
> Will this cause a previously biosdevname generated name to change on
> reinstall, or will ifnames end up with the same biosdevname-provided
> name on systems that are being supplied biosdevname data? I think I
> didn't really understand what ifnames would select in terms of servers
> with biosdevname available.

Sorry, I might have been unclear above: I meant that I'd like to stop
*seeding* biosdevname on servers, not uninstall it on upgrade. While
they both query the BIOS, I am not sure that biosdevname and ifnames
actually calculate the exact same names from that information. I never
had a machine where biosdevname would actually do anything, so I don't
know; but it seems to be a dangerous assumption that they give
identical results, so we should keep biosdevname on existing installs.

If you install a new server, that won't get biosdevname by default any
more and you'd get different names, yes. In a way that's like similar
transitions that we did in the past, like device names to UUIDs, or
even [mac] to [biosdevname].

Martin

--
Martin Pitt | http://www.piware.de
Ubuntu Developer (www.ubuntu.com) | Debian Developer (www.debian.org)