Patrick,

That's a good point. I think the issue is already being discussed at 
https://bugs.launchpad.net/nova/+bug/1039386 as Don Dugger pointed out. 

That being said, as answers to some of your questions: yes, any key/value pair 
can be used and it is user's (in this case, system admin's) responsibility to 
avoid conflict at this time. The scope we originally thought was pretty much 
static like the number of GPUs, but there is no reason why it should be static 
as some features can change dynamically. I'd encourage you to propose a 
blueprint if you can. We can also consider the feature, but our team needs to 
discuss it before we can commit to it.

Thanks,

Joseph

----- Original Message -----
From: "Patrick Petit" <patrick.michel.pe...@gmail.com>
To: "Joseph Suh" <j...@isi.edu>
Cc: "openstack@lists.launchpad.net (openstack@lists.launchpad.net)" 
<openstack@lists.launchpad.net>, "David Kang" <dk...@isi.edu>
Sent: Friday, August 24, 2012 7:37:31 PM
Subject: Re: [Openstack] [Nova] Instance Type Extra Specs clarifications

Hi Joseph and All,

You are pointing the root cause of my question. The question is about how to 
specify capabilities for a compute node so that they can be compared with the 
extra specs. I think how to define extra specs in a flavor is clear enough.

So, some capabilities are standard and are generated dynamically. Others are 
not known or not captured by the system and so not standard (yet), like the 
GPUs, and therefore must be specified somehow. Today, the somehow, as I 
understand things, is to add key/value pairs in nova.conf when/if it is 
supported.

I wanted to make sure i understand the basic principals.

Now, this in my opinion poses couple problems and/or call for additional 
questions:

What is the naming convention to add capabilities in nova.conf? I would suppose 
that any key/value pair cannot be taken for a capability.

How to avoid name clashing with standard capability? At the very least one 
should have an option to print them out (in nova-manage?). Even a simple 
written list would be helpful.

But, are we really comfortable with the idea to define static capabilities in 
nova.conf? that's putting a lot of burden on config management. Also, not 
standard doesn't imply static.

We can certainly live we that for now, But eventually, i think we'll need some 
sort of an extension mechanism so that providers can generate whatever 
capabilities they want using their own plugin? Note that capabilities could be 
software related too.

What do you think?
Best,
Patrick

Envoyé de mon iPad

Le 24 août 2012 à 18:38, Joseph Suh <j...@isi.edu> a écrit :

> Patrick,
> 
> Once a new item (key and value pair) is added to the capabilities, it can be 
> compared against extra_specs. The extra_specs can be populated in 
> instance_type_extra_specs table. The items in the extra_specs can start with 
> one of the keywords for operations such as ">=" and "s==". For example, if 
> "ngpus: 4" is populated in capability, extra_specs of ">= 2" will choose the 
> host. If the extra_specs is ">= 5", the host will not be chosen. If no 
> keyword is found at the beginning of the extra_specs (with the latest change 
> in upstream code), the given string is directly compared with capability. For 
> example, if "fpu" is given as extra_specs, the capability must be "fpu" to be 
> selected.
> 
> If more clarification is needed, please let us know.
> 
> Thanks,
> 
> Joseph
> 
> ----- Original Message -----
> From: "David Kang" <dk...@isi.edu>
> To: "Patrick Petit" <patrick.michel.pe...@gmail.com>
> Cc: "openstack@lists.launchpad.net (openstack@lists.launchpad.net)" 
> <openstack@lists.launchpad.net>
> Sent: Friday, August 24, 2012 11:34:11 AM
> Subject: Re: [Openstack] [Nova] Instance Type Extra Specs clarifications
> 
> 
> Parick,
> 
> We are using the feature in Bare-metal machine provisioning.
> Some keys are automatically generated by nova-compute.
> For example, "hypervisor_type", "hypervisor_version", etc. fields are 
> automatically
> put into capabilities by nova-compute (in the case of libvirt).
> So, you don't need to specify that.
> But, if you want to add custom fields, you should put them into nova.conf 
> file of 
> the nova-compute node.
> 
> Since the new key are put into 'capabilities', 
> the new key must be different from any other keys in the 'capabilities'.
> If that uniqueness is enforced, it can be any string, I believe.
> 
> Thanks,
> David
> 
> ----------------------
> Dr. Dong-In "David" Kang
> Computer Scientist
> USC/ISI
> 
> ----- Original Message -----
>> Hi,
>> 
>> 
>> Could someone give a practical overview of how configuring and using
>> the instance type extra specs extension capability introduced in
>> Folsom?
>> 
>> 
>> If how extending an instance type is relatively clear.
>> 
>> 
>> Eg.: #nova-manage instance_type set_key --name=<my.instancetype> --key
>> <cpu_arch> --value <'s== x86_64'>
>> 
>> 
>> The principles of capability advertising is less clearer. Is it
>> assumed that the key/value pairs are always declared statically as
>> flags in nova.conf of the compute node, or can they be generated
>> dynamically and if so, who would that be? And also, are the keys
>> completely free form strings or strings that are known (reserved) by
>> Nova?
>> 
>> 
>> Thanks in advance for clarifying this.
>> 
>> 
>> Patrick
>> _______________________________________________
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