Open Stack

Hi Thierry,


2014-03-06 11:46 GMT+01:00 Thierry Carrez <thierry at openstack.org>:

> Dina Belova wrote:
> >> Would Climate also be usable to support functionality like Spot
> >> Instances ? "Schedule when spot price falls under X" ?
> >
> > Really good question. Personally I think that Climate might help
> > implementing this feature, but probably it's not the main thing that
> > will work there.
> >
> > Here are my concerns about it. Spot instances require way of counting
> > instance price:
> > [...]
>
> Not necessarily. It's a question of whether Climate would handle only
> "schedule at" (a given date), or more generally "schedule when" (a
> certain event happens, with date just being one event type). You can
> depend on some external system setting spot prices, or any other
> information, and climate rules that would watch regularly that external
> information to decide if it's time to run resources or not. I don't
> think it should be Climate's responsibility to specifically maintain
> spot price, everyone can come up with their own rules.
>
>

I can't agree more on this. The goal of Climate is to provide some formal
contract agreement in betwen an user and the Reservation service, for
ensuring that the order will be placed and served correctly (with regards
to quotas and capacity). Of course, what we call 'user' doesn't formally
tend to be a 'real' user.
About spot instances use-case, I don't pretend to design it, but I could
easily imagine that a call to Nova for booting an instance would place an
order to Climate with a specific type of contract (what we began to call
'best-effort' and which needs to be implemented yet) where notifications
for acquitting the order would come from Ceilometer (for instance). If no
notifications come to Climate, the lease would not be honored.

See https://wiki.openstack.org/wiki/Climate#Lease_types_.28concepts.29 for
best-effort definition of a lease.

-Sylvain
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