[Openstack-operators] How to handle updates of public images?

Belmiro Moreira moreira.belmiro.email.lists at gmail.com
Thu Feb 5 21:42:29 UTC 2015

We don't delete public images from Glance because it breaks migrate/resize
and block live migration. Not tested with upstream Kilo, though.
As consequence, our public image list has been growing over time...

In order to manage image releases we use "glance image properties" to tag

Some relevant reviews:


On Thu, Feb 5, 2015 at 8:16 PM, Kris G. Lindgren <klindgren at godaddy.com>

> In the case of a raw backed qcow2 image (pretty sure that¹s the default)
> the instances root disk as seen inside the vm is made up of changes made
> on the instance disk (qcow2 layer) + the base image (raw).  Also, remember
> that as currently coded a resize migration will almost always be a
> migrate.  However, since the vm is successfully running on the old compute
> node it *should* be a trivial change that if the backing image is no
> longer available via glance - copy that over to the new host as well.
> ____________________________________________
> Kris Lindgren
> Senior Linux Systems Engineer
> GoDaddy, LLC.
> On 2/5/15, 11:55 AM, "Clint Byrum" <clint at fewbar.com> wrote:
> >Excerpts from George Shuklin's message of 2015-02-05 05:09:51 -0800:
> >> Hello everyone.
> >>
> >> We are updating our public images regularly (to provide them to
> >> customers in up-to-date state). But there is a problem: If some
> >>instance
> >> starts from image it becomes 'used'. That means:
> >> * That image is used as _base for nova
> >> * If instance is reverted this image is used to recreate instance's disk
> >> * If instance is rescued this image is used as rescue base
> >> * It is redownloaded during resize/migration (on a new compute node)
> >>
> >
> >Some thoughts:
> >
> >* All of the operations described should be operating on an image ID. So
> >the other suggestions of renaming seems the right way to go. "Ubuntu
> >14.04" becomes "Ubuntu 14.04 02052015" and the ID remains in the system
> >for a while. If something inside Nova doesn't work with IDs, it seems
> >like a bug.
> >
> >* rebuild, revert, rescue, and resize, are all very _not_ cloud things
> >that increase the complexity of Nova. Perhaps we should all reconsider
> >their usefulness and encourage our users to spin up new resources, use
> >volumes and/or backup/restore methods, and then tear down old instances.
> >
> >One way to encourage them is to make it clear that these operations will
> >only work for X amount of time before old versions images will be removed.
> >So if you spin up Ubuntu 14.04 today, reverts and resizes and rescues
> >are only guaranteed to work for 6 months. Then aggressively clean up >
> >6 month old image ids. To make this practical, you might even require
> >a role, something like "reverter", "rescuer", "resizer" and only allow
> >those roles to do these operations, and then before purging images,
> >notify those users in those roles of instances they won't be able to
> >resize/rescue/revert anymore.
> >
> >It also makes no sense to me why migrating an instance requires its
> >original image. The instance root disk is all that should matter.
> >
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