On 14/11/13 11:29, Renat Akhmerov wrote:
As for EventScheduler proposal, I think it actually fits Mistral model
very well. What described in EvenScheduler is basically the ability to
configure webhooks to be called periodically or at a certain time. First
of all, from the very beginning the concept of scheduling has been
considered a very important capability of Mistral. And from Mistral
perspective calling a webhook is just a workflow consisting of one task.
In order to simplify consumption of the service we can implement API
methods to work specifically with webhooks in a convenient way (without
providing any workflow definitions using DSL etc.). I have already
suggested before that we can provide API shortcuts for scheduling
individual tasks rather than complex workflows so it has an adjacent
meaning.
I other words, I now tend to think it doesn’t make sense to have
EventScheduler a standalone service.
I tend to agree. What OpenStack doesn't yet have is a language for
defining actions (Heat explicitly avoids this). This is required to
define what to do in both a workflow task and a scheduled task and we
only want to define it once, so workflow-as-a-service and
cron-as-a-service (yeah, I know, people hate it when I call it that) are
closely related at that level. Given this, it seems easiest to make the
latter a feature of the former. I can easily imagine that you'll want to
include scheduled tasks in your workflows too.
What might be a downside is that sharing a back-end may not be
technically convenient - one thing we have been reminded of in Heat is
that a service with timed tasks has to be scaled out in a completely
different way to a service that avoids them. This may or may not be an
issue for Mistral, but it could be resolved by having different back-end
services that communicate over RPC. The front-end API can remain shared
though.
cheers,
Zane.
What do you think?
Renat
On 13 Nov 2013, at 06:39, Angus Salkeld <[email protected]
<mailto:[email protected]>> wrote:
On 12/11/13 15:13 -0800, Christopher Armstrong wrote:
Given the recent discussion of scheduled autoscaling at the summit
session
on autoscaling, I looked into the state of scheduling-as-a-service in and
around OpenStack. I found two relevant wiki pages:
https://wiki.openstack.org/wiki/EventScheduler
https://wiki.openstack.org/wiki/Mistral/Cloud_Cron_details
The first one proposes and describes in some detail a new service and API
strictly for scheduling the invocation of webhooks.
The second one describes a part of Mistral (in less detail) to
basically do
the same, except executing taskflows directly.
Here's the first question: should scalable cloud scheduling exist
strictly
as a feature of Mistral, or should it be a separate API that only does
event scheduling? Mistral could potentially make use of the event
scheduling API (or just rely on users using that API directly to get
it to
execute their task flows).
Second question: if the proposed "EventScheduler" becomes a real project,
which OpenStack Program should it live under?
Third question: Is anyone actively working on this stuff? :)
Your work mates;)https://github.com/rackerlabs/qonos
how about merge qonos into mistral, or at lest put it into stackforge?
-Angus
--
IRC: radix
Christopher Armstrong
Rackspace
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