Open Stack

On Wed, Jun 25, 2014 at 1:40 AM, Abbass MAROUNI <
abbass.marouni at virtualscale.fr> wrote:

>
> 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.
>

You have just touched on a long outstanding issue in OpenStack, how to do
cross service scheduling. I don't think the tag model you proposed is
sufficient, as there is no guarantee that a volume on node x will be
available in a second from now. While a good solution to this issue is a
ways off I think there may be an easier short term ugly hack. As an
administrator, you can already find out what host an instance is on (AFAIK
'nova show UUID' should give you the information).



>
> Thanks,
>
>
> 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.
>>
>>
> --
> --
> Abbass MAROUNI
> VirtualScale
>
>
>
>
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack-dev/attachments/20140708/6afb8cba/attachment.html>