Re: EL6 initscript feedback.

[Gordan Bobic <gordan@bobich.net>]

On 05/21/2013 06:00 PM, Pasi Kärkkäinen wrote:
> On Tue, May 21, 2013 at 01:02:35PM +0100, Stefano Stabellini wrote:
>> On Tue, 21 May 2013, Gordan Bobic wrote:
>>> On Tue, 21 May 2013 21:30:27 +1000, Steven Haigh <netwiz@crc.id.au> wrote:
>>>> On 05/21/2013 09:20 PM, Stefano Stabellini wrote:
>>>>> On Tue, 21 May 2013, Steven Haigh wrote:
>>>>>> Hi all,
>>>>>>
>>>>>> I'm throwing in my initscript here that I've been pushing to autostart
>>>>>> xen
>>>>>> domains on system boot.
>>>>>>
>>>>>> There are at least one issue right now that I'm not 100% sure how to
>>>>>> handle -
>>>>>> and that is domains created by libvirt. These continue to show in an
>>>>>> xm/xl
>>>>>> list output even when they are not paused / running / blocked - causing
>>>>>> my
>>>>>> initscript to think they are still running.
>>>>>>
>>>>>> The ways I can think of detecting this are *very* hacky and I wouldn't
>>>>>> feel
>>>>>> comfortable to including them in widely used packages.
>>>>>>
>>>>>> I'm wondering if people have some spare time that they review the logic
>>>>>> in
>>>>>> this initscript and provide feedback / suggestions / fixes /
>>>>>> improvements that
>>>>>> I can roll into the scripts to enhance them for all.
>>>>>
>>>>> Is it actually a good idea to mix and match different toolstacks on the
>>>>> same host? If somebody intends to use libvirt, surely she would want to
>>>>> use it for everything?
>>>>
>>>> This is the interesting question... which probably leads into a more
>>>> important question... What is the best practices for config management
>>>> and defining configuration for DomU's?
>>>>
>>>> While I recommend that people use a plain text config file in
>>>> /etc/xen (although really the files can be just about anywhere) and
>>>> then links to various auto-start DomU's in /etc/xen/auto as a general
>>>> rule.
>>>>
>>>> Am I correct in thinking that libvirt only keeps details of domains
>>>> in the xenstore? Is this recommended? Although more a libvirt question
>>>> - can libvirt be configured to use config files in /etc/xen or
>>>> similar?
>>>
>>> I think this is largely distribution dependant. In the case of EL/Fedora,
>>> libvirt seems to be the distro's intended way of managing VMs, at least for
>>> their primary supported virtualization method (KVM).
>>>
>>> In the interest of clarity and maintainability I have seen the light
>>> and converted my VMs to simple text files in /etc/xen/ (there seems to be
>>> no documentation on how to edit most of the settings in xenstore). Some
>>> consensus on the best way would be good, though.
>>
>> I think that using simple text files in /etc/xen for VM configs is
>> clearly the right way to go from the Xen POV.
>>
>
> Earlier libvirt versions, such as the default version in rhel5/centos5,
> creates /etc/xen/<vm> text files upon VM creation. Later libvirt versions changed the model
> to use xend managed domains with libvirt xml configs.
>
> I wonder if that behaviour could be changed with some config option.. would be nice.
>
> Also to convert from libvirt xml to xen text files you can use this:
>
> virsh dumpxml vm_name > /tmp/a
> virsh domxml-to-native xen-xm /tmp/a > /etc/xen/vm_name
>
> Works for me on centos6 Xen (libvirt 0.10.2).

EL6 seems to keep the VM configs in xenstore, not in xml files.

Gordan