[openstack-dev] Nova config drive rebuilding

Scott Moser smoser at ubuntu.com
Wed Aug 7 07:41:23 UTC 2013

On Wed, 7 Aug 2013, Robert Collins wrote:

> On 7 August 2013 18:08, Uri Simchoni <uri_simchoni at hotmail.com> wrote:
> > Hi,
> >
> > As far as I can tell (from testing and looking at the code, at least for libvirt driver), the config drive is not rebuilt after initial spawning (except for some migration scenarios), which means the guest cannot see updates to its metadata.
> >
> > Is this a valid statement, and would it make sense to have the disk rebuilt on events such as suspend/resume or stop/start?
> Thats certainly my understanding and one of the reasons I dislike it :).
> Being able to update it when the guest is restarted would be an
> improvement IMO - but note that the EC2 metadata service is largely
> static too; thats something I'd like to see us change (e.g. making ssh
> keys more dynamic)... but thats a different story.
> I suggest putting a blueprint together, as the exact places where it's
> safe to update an instance-mounted image will need careful
> identification.

Its never ok to update an 'instance-mounted' , and realistically you have
no way of knowing the difference between 'instance-mounted' and
'instance-attached'. I'd say on reboot and shutdown you can update it, but
thats really hardly useful as a mechanism to get an instance new

My general impression was that as we got neutron functional there was a
moving back towards acceptance of the metadata service.
The dynamic nature of a web service is *so* useful.

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