[libvirt] Proper behavior when "creating" a new transient domain with same name/uuid as existing persistent domain

[Daniel P. Berrange]

On Mon, Apr 21, 2014 at 09:43:21AM -0600, Eric Blake wrote:
> On 04/21/2014 05:13 AM, Laine Stump wrote:
> > Playing around with the network driver I found that if I net-define a
> > network, then net-create using a slightly modified version of the same
> > XML file (e.g. different bridge name, but same name/uuid) the following
> > will happen:
> > 
> > 1) a network of that name is started, it is persistent, and it has the
> > properties from the modified XML file (the one given to net-create).
> > 
> > 2) both "net-dumpxml" and "net-dumpxml --inactive" will show the
> > modified attributes.
> > 
> > 3) when I net-destroy the network, the network will still exist (since
> > it is still persistent), but will have all of the modified attributes
> > rather than the originals.
> > 
> > Wanting the network driver to behave consistently with the qemu driver,
> > I did the same test with a qemu domain. I found exactly the same behavior.
> > 
> > I would have expected that when I tried to create a domain (or network)
> > with the same name & UUID as an existing persistent&inactive domain (or
> > network) that one of the following two things would happen:
> > 
> > 1) the operation would fail because a persistent domain/network already
> > existed
> 
> No, we explicitly document that attempting to 'create' something that
> already exists as an inactive persistent object is merely longhand for
> 'start'ing the existing object.
> 
> > 
> > 2) the domain/network would be started with the modified attributes, but
> > the persistent definition would still show the original attributes,
> > which would remain after destroying the transient
> 
> Well, it's really only one object.  But yes, I'd expect the persistent
> definition to remain unchanged, and that the temporary modified
> definition passed through 'create' is lost once the object is no longer
> active.

Yes, that is what /used/ to happen. If you boot from a transient XML
config, that should not impact the persistent config once the guest
is shutoff again.


Regards,
Daniel
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