<div dir="ltr"><br><div class="gmail_extra"><br><br><div class="gmail_quote">On Tue, Jun 25, 2013 at 7:22 AM, Andrew Laski <span dir="ltr"><<a href="mailto:andrew.laski@rackspace.com" target="_blank">andrew.laski@rackspace.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">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 <a href="https://blueprints.launchpad.net/nova/+spec/shelve-instance" target="_blank">https://blueprints.launchpad.<u></u>net/nova/+spec/shelve-instance</a><u></u>, but to make things easy I'll outline some of the goals here.<br>
<br>
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.<br>
</blockquote><div><br></div><div><br></div><div><div>the part that caught my eye as something that *may* be in heat's domain and is at least worth a discussion is the snapshotting and periodic task part.</div><div><br>
</div><div>from what I can tell, it sounds like the use case is for this is: I want to 'shutdown' my VM overnight and save money since I am not using it, but I want to keep everything looking the same.</div><div>
<br></div><div>But in this use case I would want to automatically 'shelve' my instance off the compute-server every night (not leave it on the server) and every morning I would want it to autostart before I get to work (and re-attach my volume and re-associate my floating-ip). All of this sounds much closer to using heat and snapshotting then using 'shelving.'</div>
</div><div><br></div><div style>Additionally, storing the shelved instance locally on the compute-node until a simple periodic task to migrates 'shelved' instances off into deep storage seems like it has undesired side-effects. For example, as long as the shelved instance is on a compute-node, you have to reserve CPU resources for it, otherwise the instance may not be able to resume on the same compute-node invalidating the benefits (as far as I can tell) of keeping the instance locally snapshotted.</div>
<div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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>From a user standpoint what they're looking for is:<br>
<br>
The ability to retain the endpoint for API calls on that instance. So v2/<tenant_id>/servers/<<u></u>server_id> continues to work after the instance is unshelved.<br>
<br>
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.<br>
<br>
The ability to see that instance in their list of servers when shelved.<br></blockquote><div><br></div><div style>This sounds like a good reason to keep this in nova.</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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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.<br>
</blockquote><div><br></div><div style>What properties are those, and more importantly why I need them?</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">
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So I'd like to understand what the thinking is around why this belongs in Heat, and how that could be accomplished.<br>
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</blockquote></div><br></div></div>