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On 01/09/2017 05:15 AM, Flavio Percoco wrote:
> On 06/01/17 09:34 +0530, Rabi Mishra wrote:
>> On Fri, Jan 6, 2017 at 4:38 AM, Emilien Macchi <emilien at redhat.com>
>> wrote:
>>
>>> Greetings Heat folks!
>>>
>>> My question is simple:
>>> When do you plan to support Glance v2?
>>> https://review.openstack.org/#/c/240450/
>>>
>>> The spec looks staled while Glance v1 was deprecated in Newton (and v2
>>> was started in Kilo!).
>>>
>>>
>> Hi Emilien,
>>
>> I think we've not been able to move to v2 due to v1/v2 incompatibility[1]
>> with respect to the location[2] property. Moving to v2 would break all
>> existing templates using that property.
>>
>> I've seen several discussions around that without any conclusion.  I
>> think
>> we can support a separate v2 image resource and deprecate the current
>> one,
>> unless there is a better path available.
> 
> Hi Rabi,
> 
> Could you elaborate on why Heat depends on the location attribute? I'm not
> familiar with Heat and knowing this might help me to propose something
> (or at
> least understand the difficulties).
> 
> I don't think putting this on hold will be of any help. V1 ain't coming
> back and
> the improvements for v2 are still under heavy coding. I'd probably
> recommend
> moving to v2 with a proper deprecation path rather than sticking to v1.

I'm going to agree with Flavio here. However, it's worth noting what Tim
said:


> Would this be backwards compatible (i.e. the old image resource would
> still work without taking advantage of the new functions) or would heat
> users have to change their templates?
>
> It would be good if there is a way to minimise the user impact.

Which I also agree with.

Normally I'd say that heat could be clever and code around such a thing
- but from v1 to v2 the entire concept of an external image location was
removed, so there is no possibility of compat. While I love to rant
about breaking compat ... this is, at this point, a _VERY_ old break
that happened back when people thought it was ok for us to release new
Major versions of OpenStack APIs. We no longer think that - but the
glance v2, cinder v2/3 and keystone v3 are essentially all water under
the bridge. (for the record, I believe you can find an argument between
bcwaldon and I from the folsom/grizzly time frame about the evils of
major version bumps, but I lost the argument at the time)

Honestly, I'd just add an error message if someone tries to use the
location field on a glance v2 cloud that says:

"This cloud does not support referencing external or pre-existing image
locations. Please upload the image directly to glance." - with maybe a
link to a doc page that explains how to write a template that does the
new thing.

Heat users using heat to upload images are going to have to rewrite
their templates to deal with direct upload rather than external
reference at some point. It's not going to get any easier for them the
longer we let them continue to shoot themselves in the foot by using the
location field.

Monty

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