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<div>On Dec 5, 2013, at 4:45 PM, Steve Baker <<a href="mailto:sbaker@redhat.com">sbaker@redhat.com</a>></div>
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<div class="moz-cite-prefix">On 12/06/2013 10:46 AM, Mark Washenberger wrote:<br>
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<div class="gmail_quote">On Thu, Dec 5, 2013 at 1:05 PM, Vishvananda Ishaya <span dir="ltr">
<<a moz-do-not-send="true" href="mailto:vishvananda@gmail.com" target="_blank">vishvananda@gmail.com</a>></span> wrote:<br>
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On Dec 5, 2013, at 12:42 PM, Andrew Plunk <<a moz-do-not-send="true" href="mailto:andrew.plunk@RACKSPACE.COM">andrew.plunk@RACKSPACE.COM</a>> wrote:<br>
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>> Excerpts from Randall Burt's message of 2013-12-05 09:05:44 -0800:<br>
>>> On Dec 5, 2013, at 10:10 AM, Clint Byrum <clint at <a moz-do-not-send="true" href="http://fewbar.com/" target="_blank">
fewbar.com</a>><br>
>>> wrote:<br>
>>><br>
>>>> Excerpts from Monty Taylor's message of 2013-12-04 17:54:45 -0800:<br>
>>>>> Why not just use glance?<br>
>>>>><br>
>>>><br>
>>>> I've asked that question a few times, and I think I can collate the<br>
>>>> responses I've received below. I think enhancing glance to do these<br>
>>>> things is on the table:<br>
>>>><br>
>>>> 1. Glance is for big blobs of data not tiny templates.<br>
>>>> 2. Versioning of a single resource is desired.<br>
>>>> 3. Tagging/classifying/listing/sorting<br>
>>>> 4. Glance is designed to expose the uploaded blobs to nova, not users<br>
>>>><br>
>>>> My responses:<br>
>>>><br>
>>>> 1: Irrelevant. Smaller things will fit in it just fine.<br>
>>><br>
>>> Fitting is one thing, optimizations around particular assumptions about the size of data and the frequency of reads/writes might be an issue, but I admit to ignorance about those details in Glance.<br>
>>><br>
>><br>
>> Optimizations can be improved for various use cases. The design, however,<br>
>> has no assumptions that I know about that would invalidate storing blobs<br>
>> of yaml/json vs. blobs of kernel/qcow2/raw image.<br>
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> I think we are getting out into the weeds a little bit here. It is important to think about these apis in terms of what they actually do, before the decision of combining them or not can be made.<br>
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> I think of HeatR as a template storage service, it provides extra data and operations on templates. HeatR should not care about how those templates are stored.<br>
> Glance is an image storage service, it provides extra data and operations on images (not blobs), and it happens to use swift as a backend.<br>
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This is not completely correct. Glance already supports something akin to templates. You can create an "image" with metadata properties that specifies a complex block device mapping which would allow for multiple volumes and images to connected to the vm at
boot time. This is functionally a template for a single vm.<br>
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Glance is pretty useless if is just an "image storage" service, we already have other places that can store bits (swift, cinder). It is much more valuable as a searchable repository of bootable templates. I don't see any reason why this idea couldn't be extended
to include more complex templates that could include more than one vm.<br>
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<div>FWIW I agree with all of this. I think Glance's real role in OpenStack is as a helper and optionally as a gatekeeper for the category of "stuff Nova can boot". So any parameter that affects what Nova is going to boot should in my view be something Glance
can be aware of. This list of parameters *could* grow to include multiple device images, attached volumes, and other things that currently live in the realm of flavors such as extra hardware requirements and networking aspects.</div>
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<div>Just so things don't go too crazy, I'll add that since Nova is generally focused on provisioning individual VMs, anything above the level of an individual VM should be out of scope for Glance.</div>
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<div>I think Glance should alter its approach to be less generally agnostic about the contents of the objects it hosts. Right now, we are just starting to do this with images, as we slowly advance on offering server side format conversion. We could find similar
use cases for single vm templates.</div>
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The average heat template would provision more than one VM, plus any number of other cloud resources.<br>
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An image is required to provision a single nova server;<br>
a template is required to provision a single heat stack.<br>
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Hopefully the above "single vm" policy could be reworded to be agnostic to the service which consumes the object that glance is storing.<br>
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<div>To add to this, is it that Glance wants to be *more* integrated and geared towards vm or container images or that Glance wishes to have more intimate knowledge of the things its cataloging *regardless of what those things actually might be*? The reason
I ask is that Glance supporting only "single vm templates" when Heat orchestrates the entire (or almost entire) spectrum of core and integrated projects means that its suitability as a candidate for a template repository plummets quite a bit.</div>
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