Deltacloud Tracker Design (Draft)

David Lutterkort lutter at redhat.com
Fri Jun 8 12:30:47 UTC 2012


On Fri, 2012-06-08 at 13:12 +0200, Jan Provazník wrote:
> On 06/08/2012 12:31 PM, David Lutterkort wrote:
> > [ Adding dev at deltacloud ]
> >
> > On Thu, 2012-06-07 at 21:15 +0200, Jan Provazník wrote:
> >> Hi Lutter,
> >> Michal pointed me to your draft of Tracker design which looks great.
> >> Couple of notes are inline. Sending it to aeolus-devel list too so
> >> others can join.
> >>
> >> Original doc can be found here:
> >> https://raw.github.com/lutter/deltacloud/tracker/design/site/content/tracker.mdown
> >
> > And the pretty version is at
> > http://people.apache.org/~lutter/deltacloud/tracker.html
> >
> >>> The resource changes that will trigger a notification to clients are
> >>> specific to each resource (and driver ?) They are
> >>>
> >>> * Instances: change to instance state
> >>> * [TODO: what else ?]
> >>
> >> Realms are needed too. We check realms availability in Conductor, so we
> >> will not be able to replace our current checking tool with Tracker until
> >> realms are supported too.
> >
> > Realms is something that gets measured indirectly, right ? I.e., realm
> > availability is based on success/failure of launching/running instances
> > in that realm.
> >
> 
> No, we check periodically realm's availability (unavailable realms are 
> then ignored when launching an instance).

How do you check ?

> > What we need is slightly different from what delayed job gives you: we
> > need cron-like functionality to run tasks at fixed intervals, whereas
> > delayed job is used for handling one-shot tasks in the background. It's
> > possible to use delayed job for this, but hopefully somebody else has
> > come up with something that is closer. (Haven't looked yet)
> >
> 
> True, we were choosing some tool for this purpose on Aeolus side too few 
> weeks/months ago (before we knew about Tracker). Richard Su made lot of 
> work in this area (CCing him) so it would worh discuss this with him, 
> wiki page with related stuff is here:
> https://www.aeolusproject.org/redmine/projects/aeolus/wiki/Background_Processing
>
> mail thread is here:
> https://fedorahosted.org/pipermail/aeolus-devel/2012-April/009923.html
 
Nice. Has anybody looked at clockwork[1] together with delayed job ? I
like the idea of separating the scheduler from the queue manager.

David

[1] https://github.com/adamwiggins/clockwork




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