[openstack-dev] [heat] [glance] Heater Proposal

Angus Salkeld asalkeld at redhat.com
Fri Dec 6 00:32:02 UTC 2013

On 05/12/13 11:35 -0500, James Slagle wrote:
>On Thu, Dec 5, 2013 at 11:10 AM, Clint Byrum <clint at fewbar.com> wrote:
>> Excerpts from Monty Taylor's message of 2013-12-04 17:54:45 -0800:
>>> Why not just use glance?
>> I've asked that question a few times, and I think I can collate the
>> responses I've received below. I think enhancing glance to do these
>> things is on the table:
>I'm actually interested in the use cases laid out by Heater from both
>a template perspective and image perspective.  For the templates, as
>Robert mentioned, Tuskar needs a solution for this requirement, since
>it's deploying using templates.  For the images, we have the concept
>of a "golden" image in TripleO and are heavily focused on image based
>deployments.  Therefore, it seems to make sense that TripleO also
>needs a way to version/tag known good images.
>Given that, I think it makes sense  to do this in a way so that it's
>consumable for things other than just templates.  In fact, you can
>almost s/template/image/g on the Heater wiki page, and it pretty well
>lays out what I'd like to see for images as well.
>> 1. Glance is for big blobs of data not tiny templates.
>> 2. Versioning of a single resource is desired.
>> 3. Tagging/classifying/listing/sorting
>> 4. Glance is designed to expose the uploaded blobs to nova, not users
>> My responses:
>> 1: Irrelevant. Smaller things will fit in it just fine.
>> 2: The swift API supports versions. We could also have git as a
>> backend.
>I would definitely like to see a git backend for versioning.  No
>reason to reimplement a different solution for what already works
>well.  I'm not sure we'd want to put a whole image into git though.
>Perhaps just it's manifest (installed components, software versions,
>etc) in json format would go into git, and that would be associated
>back to the binary image via uuid.  That would even make it easy to
>diff changes between versions, etc.
>> This feels like something we can add as an optional feature
>> without exploding Glance's scope and I imagine it would actually be a
>> welcome feature for image authors as well. Think about Ubuntu maintaining
>> official images. If they can keep the ID the same and just add a version
>> (allowing users to lock down to a version if updated images cause issue)
>> that seems like a really cool feature for images _and_ templates.
>> 3: I'm sure glance image users would love to have those too.
>> 4: Irrelevant. Heat will need to download templates just like nova, and
>> making images publicly downloadable is also a thing in glance.
>> It strikes me that this might be a silo problem instead of an
>> actual design problem. Folk should not be worried about jumping into
>> Glance and adding features. Unless of course the Glance folk have
>> reservations? (adding glance tag to the subject)
>I'm +1 for adding these types of features to glance, or at least
>something common, instead of making it specific to Heat templates.

+1 from me too, I don't see a reason for Heater at all, just add
the features to glance. Especially since Tuskar/TripelO have
overlapping needs. Just seems crazy not to all benefit from combining
efforts. (assuming glance are happy with the extension).

And there is a huge overhead to a new project.


>-- James Slagle
>OpenStack-dev mailing list
>OpenStack-dev at lists.openstack.org

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