[vdsm] Per device custom properties

[Yair Zaslavsky]

----- Original Message -----
> From: "Itzik Brown" <ItzikB at mellanox.com>
> To: "Dan Kenigsberg" <danken at redhat.com>, "Assaf Muller" <amuller at redhat.com>, "Yair Zaslavsky"
> <yzaslavs at redhat.com>, "Eldan Hildesheim" <ehildesh at redhat.com>, izikb at mellanox.com
> Cc: vdsm-devel at lists.fedorahosted.org, arch at ovirt.org, "Irena Berezovsky" <irenab at mellanox.com>
> Sent: Wednesday, March 20, 2013 9:17:08 AM
> Subject: RE: [vdsm] Per device custom properties
> 
> Hi,
> 
> I think that this feature is a good start for enabling vendor
> specific hints which apply to VM Network/Disk devices.
> There is a need to add migration  hooks to the list.
> 
> Itzik
> 
> -----Original Message-----
> From: Dan Kenigsberg [mailto:danken at redhat.com]
> Sent: יום ג 19 מרץ 2013 17:12
> To: Assaf Muller; Yair Zaslavsky; Eldan Hildesheim;
> izikb at mellanox.com
> Cc: vdsm-devel at lists.fedorahosted.org; arch at ovirt.org
> Subject: Re: [vdsm] Per device custom properties
> 
> adding arch at ovirt, as this feature is cross sub-project
> 
> On Sun, Mar 17, 2013 at 09:50:20AM -0400, Assaf Muller wrote:
> > Hi all,
> > 
> > Right now we have the ability to define VM-wide properties that may
> > be
> > used by hooks.
> > It is time we have the same functionality on a device basis:
> > http://www.ovirt.org/Features/Device_Custom_Properties
> 
> This feature page needs some love and attention.
> 
> * I received a private communication about the suggested GUI: there
>   should not be an independent vNIC action called "custom Properties"
>   -
>   the dialog for editing per-vNIC custom properties should be part of
>   defining a new vNIC or editting an existing one. I believe Eldan
>   (our
>   GUI designer) concurs.
> 
> * http://www.ovirt.org/Features/Device_Custom_Properties#Engine is
>   rather lacking concrete details. Yair, could you improve it, as
>   well
>   as the completely empty REST section?

I would prefer Michael Pasternak handles REST-API.
Regarding the rest of the engine side- I'll assist.
I would consult with Eli on this, as he was/is the feature owner of VM devices.

> 
> >
> > For example: If the VM has 2 disks called disk1 and disk2, and two
> > NICs called nic1 and nic2, and the admin (From the engine) added a
> > custom property qos: 0.5 for nic1 and a custom property defrag:
> > None
> > for disk2. When the VM is started we'll run a hook for nic1 with
> > its
> > XML and qos: 0.5 added as an environment variable, and a hook for
> > disk2 with its XML and defrag: None.
> > 
> > When a device is hot plugged and it has custom properties we'll run
> > that hook as well.
> > 
> > Implementation-wise, hot plug/unplug for disks and NICs is dead
> > simple
> > - vmCreate is more problematic:
> > If the user set a custom property called 'qos: 0.8' for nic3, I'd
> > want
> > it exposed as an environment variable called 'qos' for hot plug nic
> > hooks, but for vmCreate I'd like to prefix the nic's alias.
> >  However,
> > when vmCreate is called we don't have the aliases for NICs and
> > disks.
> > 
> > The proposed solution is to create a new hook point called
> > something
> > like: 'before_device_creation' that will be called before vmCreate.
> > We'll then call that hook specifically for devices that contains
> > custom properties, as described in the second paragraph of this
> > mail.
> > 
> > 
> > I would love to hear smarter ideas before I move forward. Thanks!
> 
> I find it quite intuitive, but I'd rather hear if it feats Izik's use
> case.
> 
> Dan.
>