[Pkg-libvirt-maintainers] Bug#783901: Bug#783901: libvirt-daemon: libvirtd does not recognize Xen guests

[Gerald Turner]

On Sun, May 10 2015, Guido Günther wrote:
> On Fri, May 08, 2015 at 11:55:28AM -0700, Gerald Turner wrote:
>> On Fri, May 08 2015, Guido Günther wrote:
>> > On Fri, May 01, 2015 at 12:51:37PM -0700, Gerald Turner wrote:
>> > [..snip..]
>> >>   * 1.2.12: Jan 27 2015
>> >>       libxl: Add support for parsing/formating Xen XL config (Kiarie Kahurani)
>> >>       Introduce support for parsing/formatting Xen xl config format (Jim Fehlig)
>> >
>> > We could cherry pick those to our stable release.
>>
>> Nice!  However unless somebody else comes along and has the same
>> expectations that I had (i.e. libvirt recognizing Xen guests with
>> little or no configuration), I wouldn't put any effort into this.
>
> Could you attach a configuration to this bug that shows he conversion
> errors. I'll try to get this fixed so we ease the migration. That said
> there are lots of libxl changes in newer libvirt so running a
> backported 1.2.15 might make more sense.

Attached example.cfg in xl.cfg(5) format, and the produced example.xml
when running ‘virsh domxml-from-native xen-xm example.cfg >|
example.xml’.

The only problem seems to be parsing the disks, which is specified in
the xl-disk-configuration.txt¹ document, wherein it looks like the
<vdev> and <format> positional parameters were swapped from the older xm
format.

>> >> After correcting the domain XML, and restarting libvirtd once more,
>> >> things start progressing:
>> >>
>> >>   # virsh -c xen:/// list --all
>> >>    Id    Name                           State
>> >>   ----------------------------------------------------
>> >>    -     host1                          shut off
>> >>
>> >> … however “shut off” is incorrect.
>> >
>> > Stupid question but did you start the domain via virsh beforehand?
>> > If so, is there anything interesting in the daemon log? AFAIK
>> > configurations are now managed entierly via /etc/libvirt/libxl/ .
>>
>> Not stupid because that's part of the point I've subtly been trying
>> to make - I'm sticking with domU's started by /etc/init.d/xendomains
>> and /usr/sbin/xl, the "Xen way".  For four years during squeeze and
>> wheezy,
>
> I just wanted to make sure we have this documented straight: libxl
> managed xen domains aren't picked up by /usr/sbin/xl and vice versa.

Not quite.

xl managed xen domains aren't picked up by libvirt.

As for vice-versa, sorry but I haven't tried whether libvirt managed xen
domains are picked up by xl.

>> I had dropped in munin-libvirt-plugins and libvirt-bin (0.8.3 and
>> 0.9.12) for the sole purpose of monitoring the domU's memory/cpu/io.
>> This worked without any configuration other than specifying "uri
>> xen:///" in the munin-node plugin configuration.  During the
>> "heartbleed" panic, after hastily reacting to the output of
>> checkrestart, I accidently discovered that "service libvirt-guests
>> restart" actually handles restarts of these "unmanaged" domU's.
>> Fantastic!  Consequently I've been telling sysadmin colleagues that
>> libvirt is great because it integrates non-intrusively and can handle
>> heterogeneous VM environments.
>
> It's bad that this isn't true for Jessie anymore but looking at the
> uptream list it seems most distros are switching over to libvirt
> managed xen domains.

Interesting.  I wonder if systemd-machined has been integrated with
libvirt - yet another compelling reason to change management stacks.

¹ http://xenbits.xen.org/docs/4.4-testing/misc/xl-disk-configuration.txt

-- 
Gerald Turner <gturner at unzane.com>        Encrypted mail preferred!
OpenPGP: 4096R / CA89 B27A 30FA 66C5 1B80  3858 EC94 2276 FDB8 716D
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