Re: [libvirt] Fwd: Re: Intend to add OVA installation API
On Sun, Jun 24, 2012 at 10:47:01PM -0400, Bob Cochran wrote:
Ooops, I should have sent this to the list. I want to support
Doug's
suggestion, thanks.
Bob Cochran
-------- Original Message --------
Subject: Re: [libvirt] Intend to add OVA installation API
Date: Sun, 24 Jun 2012 22:45:15 -0400
From: Bob Cochran <bcochran13(a)verizon.net>
To: Doug Goldstein <cardoe(a)cardoe.com>
On 6/24/12 6:27 PM, Doug Goldstein wrote:
> On Sun, Jun 24, 2012 at 5:05 PM, Ata Bohra<ata.husain(a)hotmail.com> wrote:
>> Thanks Doug for your suggestions.
>>
>> I believe you are correct about the relation between OVA and OVF. But I am
>> not 100 % possitive about your suggestion: "defining an appropriate domain
>> in libvirt". To understand better I am sharing more details about my
plans:
>>
>> 1. Enhance libvirt interface code (libvirt.c) to provide a
>> domain-independent routine: virDomainCreateOVA, an alternate API to create
>> domain.
>> To make client code real simple, this routine can take ova path as input
>> and internally strip the OVA to extract required details. (planning to
>> define a struct to hold all essential
>> information).
>> 2. Second, to enhance ESX driver to perform ESX specfic calls.
>>
>> Given OVA is a tar file, the parsing is just another file open/read
>> operation; it would be simple to perform it inside domain_conf.c (infact I
>> have written a parser to strip information off OVA already).
>>
>> Hope to get some comments/suggestions on above steps.
>>
>> Thanks!
>> Ata
> Right. I'm suggesting you don't go that route and approach the problem
> from another angle. I did a little Googling since my last e-mail to at
> least make sure I understood the basics. So an OVF looks like the
> following:
>
> virtualappliance/package.ovf
> virtualappliance/disk1.vmdk
> virtualappliance/disk2.vmdk
> virtualappliance/cdrom.iso
> virtualappliance/en-US-resources.xml
>
> An OVA would simply be a tar of the above and named
Apparently that's what VMW defined somehow. I find a bit disturbing
that they used tar instead of some zip, as a ZIP can record indexes of
the parts and one doesn't have to scan the full tar to get the last
fragment for example.
> virtualappliance.ova package.ovf is an XML file containing the
> description of the hardware of the virtual machine, much like the XML
> that libvirt stores about domains. While en-US-resources.xml would be
> the US English descriptions of the machine and its hardware.
I looked at some resources on OVF a long time ago when starting
libvirt and strugging with the XML content. There are of course some
commonalities, but the ovf is a bit of a higher level from my POV.
> I'm suggesting you write an application that transforms
package.ovf
> into libvirt's own domain XML format and simply call
> virDomainDefineXML() rather than adding API to libvirt itself. You
> could then further extend the application to allow you to take a
> libvirt domain and export it as a OVA.
I'm sure one would have to pick some preferences as I think the OVF
data would be kind of a subset, but based on a given runtime environemnt
that should be easy. On a more general way it may be a bit hard.
> Looking at VMWare and Xen, they both treat OVA/OVF as a foreign
format
> and require a converter application to import them to their native
> internals so it wouldn't be much different than their approach.
Yes the problem is that the data defined in the OVF is not 100%
sufficient to run the guest (or guests as you can have mutiple
instances in one OVF IIRC, but I assume it seldomly used !)
Daniel
--
Daniel Veillard | libxml Gnome XML XSLT toolkit http://xmlsoft.org/
daniel(a)veillard.com | Rpmfind RPM search engine http://rpmfind.net/
http://veillard.com/ | virtualization library http://libvirt.org/