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

Fox, Kevin M kevin.fox at pnnl.gov
Thu Dec 5 18:16:27 UTC 2013

My 2 cents. Glance currently deals with single file images.

A user is going to want the heat repo to operate at a "stack" level. IE, I want to launch stack "foo".

For all but the most trivial cases, a stack is made up of more then one template. These templates should be versioned as set (stack), not separately.

So, glance would probably need to change to support "images" with multiple files. This could be done, but may be a bigger architectural change then originally considered.

From: Clint Byrum [clint at fewbar.com]
Sent: Thursday, December 05, 2013 8:10 AM
To: openstack-dev
Subject: Re: [openstack-dev] [heat] [glance] Heater Proposal

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:

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. 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)

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