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Great questions, Vlad. Comments inline.

On 12/30/2016 11:40 AM, Vladyslav Drok wrote:
> Hi all!
>
> There is a long standing problem of resources reporting in ironic virt
> driver.

That would be an understatement :)

 > It's described in a couple of bugs I've found - [0], [1].
> Switching to placement API will make things better, but still there are
> some problems there. For example, there are cases when ironic needs to
> say "this node is not available", and it reports the
> vcpus=memory_mb=local_gb as 0 in this case. Placement API does not allow
> 0s, so in [2] it is proposed to remove inventory records in this case.

Correct.

> But the whole logic here [3] seems not that obvious to me, so I'd like
> to discuss when do we need to report 0s to placement API. I'm thinking
> about the following (copy-pasted from my comment on [2]):
>
>   * If there is an instance_uuid on the node, no matter what
>     provision/power state it's in, consider the resources as used. In
>     case it's an orphan, an admin will need to take some manual action
>     anyway.

The single source of truth for Ironic instances is the Ironic database. 
If Ironic's database says that a node is consumed by an instance, then 
it should be considered by Nova to be consumed.

>   * If there is no instance_uuid and a node is in cleaning/clean wait
>     after tear down, it is a part of normal node lifecycle, report all
>     resources as used. This means we need a way to determine if it's a
>     manual or automated clean.

I don't see a need to determine manual vs. automated clean. The node is 
in a clean state; therefore the inventory of resources on that node are 
not available for a consumer of those resources to consume. So, the 
inventory should be deleted in Nova. This inventory should be re-added 
if and when the node is in a state that a consumer can grab it.

>   * If there is no instance_uuid, and a node:
>       o has a bad power state or
>       o is in maintenance
>       o or actually in any other case, consider it unavailable, report
>         available resources = used resources = 0. Provision state does
>         not matter in this logic, all cases that we wanted to take into
>         account are described in the first two bullets.

Correct. If there is no instance UUID for the node, that means there's 
no allocation for it. If there's no allocation for the node, its 
inventory can and should be deleted if the node cannot be consumed by an 
instance (for whatever reason).

Best,
-jay

> Any thoughts?
>
> [0]. https://bugs.launchpad.net/nova/+bug/1402658
> [1]. https://bugs.launchpad.net/nova/+bug/1637449
> [2]. https://review.openstack.org/414214
> [3]. https://github.com/openstack/nova/blob/1506c36b4446f6ba1487a2d68e4b23cb3fca44cb/nova/virt/ironic/driver.py#L262
>
> Happy holidays to everyone!
> -Vlad
>
>
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