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On 02/10/2014 10:54 AM, Khanh-Toan Tran wrote:

> Heat
> may orchestrate the provisioning process, but eventually the instances will be
> passed to Nova-scheduler (Gantt) as separated commands, which is exactly the
> problem Solver Scheduler wants to correct. Therefore the Instance Group API is
> needed, wherever it is used (nova-scheduler/Gantt).

I'm not sure that this follows.

First, the instance groups API is totally separate since we may want to 
schedule a number of instances simultaneously without them being part of 
an instance group.  Certainly in the case of using instance groups that 
would be one input into the scheduler, but it's an optional input.

Second, there is nothing wrong with booting the instances (or 
instantiating other resources) as separate commands as long as we 
support some kind of reservation token.

In that model, we would pass a bunch of information about multiple 
resources to the solver scheduler, have it perform scheduling *and 
reserve the resources*, then return some kind of resource reservation 
tokens back to the caller for each resource.  The caller could then 
allocate each resource, pass in the reservation token indicating both 
that the resources had already been reserved as well as what the 
specific resource that had been reserved (the compute-host in the case 
of an instance, for example).

Chris