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Excerpts from James Slagle's message of 2013-12-05 08:35:12 -0800:
> 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.
> 

Right, git for a big 'ol image makes little sense.

I'm suggesting that one might want to have two glances, one for images
which just uses swift versions and would just expose a list of versions,
and one for templates which would use git and thus expose more features
like a git remote for the repo. I'm not sure if glance has embraced the
extension paradigm yet, but this would fall nicely into it.

> > 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.
> 

Right, it may be that glance is too limited, but from what I've seen,
it is not and it already has the base concepts that "HeaTeR" wants to
have available.