[Engine-devel] Is there a 'Can run this VM?' query

[Itamar Heim]

On 01/09/2012 02:44 PM, Omer Frenkel wrote:
>
>
> ----- Original Message -----
>> From: "Roy Golan"<rgolan at redhat.com>
>> To: "Omer Frenkel"<ofrenkel at redhat.com>
>> Cc: engine-devel at ovirt.org, "Yaniv Kaul"<ykaul at redhat.com>
>> Sent: Monday, January 9, 2012 2:21:29 PM
>> Subject: Re: [Engine-devel] Is there a 'Can run this VM?' query
>>
>>
>>
>> ----- Original Message -----
>>> From: "Omer Frenkel"<ofrenkel at redhat.com>
>>> To: "Yaniv Kaul"<ykaul at redhat.com>
>>> Cc: engine-devel at ovirt.org
>>> Sent: Monday, January 9, 2012 2:06:58 PM
>>> Subject: Re: [Engine-devel] Is there a 'Can run this VM?' query
>>>
>>>
>>>
>>> ----- Original Message -----
>>>> From: "Yaniv Kaul"<ykaul at redhat.com>
>>>> To: engine-devel at ovirt.org
>>>> Sent: Monday, January 9, 2012 9:36:34 AM
>>>> Subject: [Engine-devel] Is there a 'Can run this VM?' query
>>>>
>>>> Beaker automated test system
>>>> (http://fedoraproject.org/wiki/QA/Beaker)
>>>> would like to integrate with the project, via the REST API.
>>>> Their main concern is that they'll provision VMs who would not be
>>>> able
>>>> to run on the ovirt setup.
>>>> I think there are two cases here:
>>>> 1. Provisioning a VM with X vCPUs, while there isn't a host
>>>> available
>>>> with such number of pCPUs (or similar in memory) - this is
>>>> easier,
>>>> as
>>>> it
>>>> can be 'calculated' from the setup beforehand and we can avoid
>>>> such
>>>> provisioning.
>>>> 2. More difficult - in runtime, the hosts are over-committed and
>>>> we
>>>> cannot run a VM - can we, before trying to run a VM, ask if it's
>>>> feasible? I know it's a point in time, and may be wrong in the
>>>> next
>>>> second, but if we go 'no' as an answer, it already provides good
>>>> information to Beaker to continue and look elsewhere.
>>>> Y.
>>>>
>>>
>>> there is no such query currently,
>> if we're going to supply one, we either encapsulate the canDoAction
>> to a class and re-use or
>> supply a boolean argument on the parameter class, say "dryRun", to
>> indicate command doesn't
>> perform the execute part realy.
>
> yep, RunVmCommand.CanRunVm() is public and static,
> return boolean and even fill list messages.
> this is why i said i think its easy to do it :)
> just need to check it really covers anything and behave well

I'd start from trying to understand how you would model such a query in 
the REST API for users to consume...