[openstack-dev] [Nova][Scheduler]

Abbass MAROUNI abbass.marouni at virtualscale.fr
Wed Jun 25 08:40:29 UTC 2014

Hello Joe,

Thanks for your quick reply, here's what we're trying to do :

In the scheduling process of a virtual machine we need to be able to
choose the best Host (which is a cinder-volume and nova-compute host at
the same time) that has enough volume space so that we can launch the VM
then create and attach some cinder volumes locally (on the same host).
We get the part where we check the available cinder space on each host
(in a filter) and choose the best host (that has the most free space in
a Weigher). Now we need to tell cinder to create and attach the volumes.
We need to be able to do it from Heat.

So I was thinking that if I can tag the virtual machine with the name of
the chosen host (in the Weigher) then I can extract the tag (somehow !)
and use it in heat as a dependency in the volume element (At least
that's what I'm thinking :  the virtual machine will be launched and
Heat will extract the tag then use it to create/attach the volumes).

I'm sure that there are other means to achieve this, so any help will be
greatly appreciated.


On 06/24/2014 11:38 PM, openstack-dev-request at lists.openstack.org wrote:
>> >Hi,
>> >
>> >I was wondering if there's a way to set a tag (key/value) of a Virtual
> Machine from within a scheduler filter ?
> The scheduler today is just for placement. And since we are in the process
> of trying to split it out, I don't think we want to make the scheduler do
> something like this (at least for now).
>> >
>> >I want to be able to tag a machine with a specific key/value after
> passing my custom filter
> What is your use case? Perhaps we have another way of solving it today.


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