[openstack-dev] [Nova][Schduler] Volunteers wanted for a modest proposal for an external scheduler in our lifetime

Robert Collins robertc at robertcollins.net
Sun Nov 24 18:43:51 UTC 2013

On 22 November 2013 23:55, Gary Kotton <gkotton at vmware.com> wrote:

>>> I'm looking for 4-5 folk who have:
>>>  - modest Nova skills
>>>  - time to follow a fairly mechanical (but careful and detailed work
>>> needed) plan to break the status quo around scheduler extraction
> I would be happy to take part. But prior I think that we need to iron out
> a number of issues:

Cool! Added your name to the list of volunteers, which brings us to 4,
the minimum I wanted before starting things happening.

> 1. Will this be a new service that has an API, for example will Nova be
> able to register a host and provide the host statistics.

This will be an RPC api initially, because we know the performance
characteristics of the current RPC API, and doing anything different
to that is unnecessary risk. Once the new structure is:
* stable
* gated with unit and tempest tests
* with a straightforward and well documented migration path for deployers

Then adding a RESTful API could take place.

> 2. How will the various components interact with the scheduler - same as
> today - that is RPC? Or a REST API? The latter is a real concern due to
> problems we have seen with the interactions of nova and other services

RPC initially. REST *only* once we've avoided second system syndrome.

> 3. How will current developments fit into this model?

Code sync - take a forklift copy of the code, and apply patches to
both for the one cycle.

> All in all I think that it is a very good and healthy idea. I have a
> number of reservations - these are mainly regarding the implementation and
> the service definition.
> Basically I like the approach of just getting heads down and doing it, but
> prior to that I think that we just need to understand the scope and mainly
> define the interfaces and how they can used/abused and consumed. It may be
> a very good topic to discuss at the up and coming scheduler meeting - this
> may be in the middle of the night for Robert. If so then maybe we can
> schedule another time.

Tuesdays at 1500 UTC - I'm in UTC+13 at the moment, so thats 0400
local. A leeeetle early for me :) I'll ping you on IRC about resolving
the concerns you raise, and you can proxy my answers to the sub group

> Please note that this is scheduling and not orchestration. That is also
> something that we need to resolve.

Yup, sure is.


Robert Collins <rbtcollins at hp.com>
Distinguished Technologist
HP Converged Cloud

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