[libvirt] [PATCH 0/3] Enable automatic kill of running guests

[Eric Blake]

On 06/23/2011 07:03 AM, Daniel P. Berrange wrote:
> On Thu, Jun 23, 2011 at 06:52:47AM -0600, Eric Blake wrote:
>> On 06/23/2011 04:58 AM, Daniel P. Berrange wrote:
>>> I am building an application which uses KVM to run specific tasks, rather
>>> than as a general purpose guest OS. I want to ensure that when the app
>>> exits, the guest goes away too. To enable this, this series introduces
>>> the concept of 'autokill', whereby a guest is forcably destroyed when
>>> the virConnectPtr that launched it closes. This also lets us fix a long
>>> standing problem with migration leaving an unkillable guest
>>
>> Cool!
>>
>> How does this interact with migration?  If a domain is currently marked
>> autokill on the source, should that mean that attempts to migrate it are
>> forbidden (since the connection to the source would end up being useless
>> after the migration, at which point the connection is gone and autokill
>> should kick in)?
> 
> That's a good point. I reckon we should forbid migration and save/restore
> for such guests.

save/restore might work, if you keep the connection alive in the
meantime; but seeing as how save is basically a form of migration (to a
file rather than to another host), it's probably easier to just forbid
that as well, and state that an autokill guest is one-shot.

And another thought - it might be nice to expose the qemu -snapshot
option, which creates a throwaway run of a guest (where all the disks
are snapshotted prior to running any guest code, then when qemu exits
the state rolled back to that snapshot).  Seems like a new flag could
easily expose this feature, and that it would either imply autokill or
often be used with autokill.

-- 
Eric Blake   eblake at redhat.com    +1-801-349-2682
Libvirt virtualization library http://libvirt.org

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