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I think the allure of labeling this as 'orchestration' comes from the reliance on multiple services to make this feature work.

Heck, booting an instance is something that should be handled by 'orchestration'. Booting an instance requires the cooperation of many services -- and while I won't go into the details I still have high hopes we can steer this logic out of nova and into other services for which it's more suited to.

Does that mean Heat? No. http://i.imgur.com/QZxAv.gif  -- Heat is a different type of 'orchestration'. The 'orchestration' logic I'm talking about is currently handled by Nova's conductor.

Long story short -- I think the change, where you have it, should work well and is the correct place to hold this logic when compared with similar tasks in Nova.

Brian


On Jun 25, 2013, at 10:22 AM, Andrew Laski <andrew.laski at rackspace.com>
 wrote:

> I have a couple of reviews up to introduce the concept of shelving an instance into Nova.  The question has been raised as to whether or not this belongs in Nova, or more rightly belongs in Heat.  The blueprint for this feature can be found at https://blueprints.launchpad.net/nova/+spec/shelve-instance, but to make things easy I'll outline some of the goals here.
> 
> The main use case that's being targeted is a user who wishes to stop an instance at the end of a workday and then restart it again at the start of their next workday, either the next day or after a weekend.  From a service provider standpoint the difference between shelving and stopping an instance is that the contract allows removing that instance from the hypervisor at any point so unshelving may move it to another host.
> 
> From a user standpoint what they're looking for is:
> 
> The ability to retain the endpoint for API calls on that instance.  So v2/<tenant_id>/servers/<server_id> continues to work after the instance is unshelved.
> 
> All networking, attached volumes, admin pass, metadata, and other user configurable properties remain unchanged when shelved/unshelved.  Other properties like task/vm/power state, host, *_at, may change.
> 
> The ability to see that instance in their list of servers when shelved.
> 
> 
> 
> Again, the objection that has been raised is that it seems like orchestration and therefore would belong in Heat.  While this is somewhat similar to a snapshot/destroy/rebuild workflow there are certain properties of shelving in Nova that I can't see how to reproduce by handling this externally.  At least not without exposing Nova internals beyond a comfortable level.
> 
> So I'd like to understand what the thinking is around why this belongs in Heat, and how that could be accomplished.
> 
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