About XCP OpenNebula integration

About XCP OpenNebula integration

[Tino Vazquez]

Dear list,

We (the OpenNebula Team) are very interested in integrating OpenNebula
with XCP. At the moment, OpenNebula can interface with the Xen
hypervisor, but since XCP appears to be much more than just Xen, I
would like to ask a couple of questions to the XCP developers in order
to define the direction we may take on this integration.

 * At the moment, ONE creates a text file that describes the VM in
terms that Xen understands, and this is processed by the "xm" command.
In XCP, there is a "xe" command with a completely different set of
options. The question is: can the same text file be used to launch a
VM in XCP? Or the approach must be something different, using the
functionality offered by "xe" or by XAPI?

* Can we get access to the "xm" command on a XCP server? Is there ways
to access the built in Xen hypervisor? Or XCP is so different that
this is not possible?

We would appreciate any feedback on this. We are committed to
integrate OpenNebula and XCP, so any help will be more than welcome.

Regards,

-Tino

--
Constantino Vázquez Blanco, MSc
OpenNebula Major Contributor  / Cloud Researcher
www.OpenNebula.org | @tinova79

Re: [Xen-devel] About XCP OpenNebula integration

[Todd Deshane]

On Tue, Feb 1, 2011 at 1:25 PM, Tino Vazquez <tinova-oqFaJxR5AkvFKiuWU8UaTg@public.gmane.org> wrote:
> Dear list,
>

You're probably also going to want feedback from the xen-api list,
adding them to the CC.


> We (the OpenNebula Team) are very interested in integrating OpenNebula
> with XCP.

Great! We (Xen.org) are very interested in helping you with the process.

> At the moment, OpenNebula can interface with the Xen
> hypervisor, but since XCP appears to be much more than just Xen, I
> would like to ask a couple of questions to the XCP developers in order
> to define the direction we may take on this integration.
>
>  * At the moment, ONE creates a text file that describes the VM in
> terms that Xen understands, and this is processed by the "xm" command.

XCP has a near equivalent with the xl command, which uses the libxl
backend. Backwards compatibility (with the exception of being able to
use arbitrary python code embedded) is the goal.

> In XCP, there is a "xe" command with a completely different set of
> options. The question is: can the same text file be used to launch a
> VM in XCP? Or the approach must be something different, using the
> functionality offered by "xe" or by XAPI?

xe is a frontend to xapi. You will likely need a new driver for this.
There is work in progress on the libvirt side of things for xapi
support

This thread made shed some more light on the issue
subject: "[Xen-devel] Re: [libvirt] [RFC] libxenlight driver"

http://xen.markmail.org/search/?q=libxenlight+rfc#query:libxenlight%20rfc+page:1+mid:r3ez5hr6j6qzwoem+state:results

> * Can we get access to the "xm" command on a XCP server? Is there ways
> to access the built in Xen hypervisor? Or XCP is so different that
> this is not possible?
>

see xl command from above.

> We would appreciate any feedback on this. We are committed to
> integrate OpenNebula and XCP, so any help will be more than welcome.
>

Please let us know if you need more detail or have more questions.

Thanks,
Todd

Re: Re: [Xen-devel] About XCP OpenNebula integration

[Vincent Hanquez]

On 02/02/11 05:08, Todd Deshane wrote:
> On Tue, Feb 1, 2011 at 1:25 PM, Tino Vazquez<tinova-oqFaJxR5AkvFKiuWU8UaTg@public.gmane.org>  wrote:
>> Dear list,
>>
>
> You're probably also going to want feedback from the xen-api list,
> adding them to the CC.
>
>
>> We (the OpenNebula Team) are very interested in integrating OpenNebula
>> with XCP.
>
> Great! We (Xen.org) are very interested in helping you with the process.
>
>> At the moment, OpenNebula can interface with the Xen
>> hypervisor, but since XCP appears to be much more than just Xen, I
>> would like to ask a couple of questions to the XCP developers in order
>> to define the direction we may take on this integration.
>>
>>   * At the moment, ONE creates a text file that describes the VM in
>> terms that Xen understands, and this is processed by the "xm" command.
>
> XCP has a near equivalent with the xl command, which uses the libxl
> backend. Backwards compatibility (with the exception of being able to
> use arbitrary python code embedded) is the goal.

sorry Todd, I think the suggestion is a bit misleading. That XCP use or 
not xl or libxl doesn't change anything on the frontend part.

Tino, surely by "interface with the Xen hypervisor" you mean opennebula 
talk with the Xend protocol (through xm). XCP is different, in that xend 
has been replaced by a more powerful and stable daemon, so xend and xm 
are not available anymore. However the Xen hypervisor is the same 
component as when you use xend.

xe is the only way to talk to the "xend" equivalent (called xapi) in 
XCP. It doesn't have the same text file approch, instead it use a more 
powerful RPC based method. the equivalent would be a sequence of 
"VM.create, VM.set .. VM.set, VBD.create, VIF.create ..."

And last bit, using xl in parallel with xapi is probably a good way to 
shoot yourself in the foot. One must certainly not try to xl create vm 
when xapi is running.

>> * Can we get access to the "xm" command on a XCP server? Is there ways
>> to access the built in Xen hypervisor? Or XCP is so different that
>> this is not possible?
>>
>
> see xl command from above.

It ultimately depends on what kind of access to the hypervisor you need.

-- 
Vincent

Re: About XCP OpenNebula integration

[Ian Campbell]

On Wed, 2011-02-02 at 05:08 +0000, Todd Deshane wrote:
> On Tue, Feb 1, 2011 at 1:25 PM, Tino Vazquez <tinova@opennebula.org> wrote:
> >  * At the moment, ONE creates a text file that describes the VM in
> > terms that Xen understands, and this is processed by the "xm" command.
> 
> XCP has a near equivalent with the xl command, which uses the libxl
> backend. Backwards compatibility (with the exception of being able to
> use arbitrary python code embedded) is the goal.

XCP does not currently include a version of Xen which includes xl or
libxl. Even in the future when it does xl will be there only as a
debugging aid for developers and will not be a supported mechanism for
interacting with an XCP host.

The XCP toolstack is xapi -- the supported way of interacting with XAPI
host is via the XenAPI XML/RPC mechanism.

One day we hope xapi will also use libxl, but this is not the same as
using xl which is a different toolstack designed to provide
compatibility with xend.

> > In XCP, there is a "xe" command with a completely different set of
> > options.

"xe" is a command line client which speaks the XenAPI XML/RPC protocol
(modulo some uninteresting implementation details) 

>  The question is: can the same text file be used to launch a
> > VM in XCP? Or the approach must be something different, using the
> > functionality offered by "xe" or by XAPI?

Integrating with XenAPI is the right way to integrate with XCP. In
general I think it would be recommended that something like OpenNebula
integration uses the XML/RPC interface directly rather than forking xe
and parsing the results.

Ian.

Re: About XCP OpenNebula integration

[Tino Vazquez]

Hi all,

First of all, many thanks for the swift and quality answers.

>From Stefano Stabellini's mail I understand that xend and the "xm"
command can even disappear from the Xen standalone hypervisor
distribution. Therefore, I think the proper way to implement this is
to follow your recommendations and use the XMLRPC API to interface
with XCP. There has been requests from the community to develop such a
driver, and I think it's time to get to it ;).

Another question regarding the Xen standalone, since "xend" is going
away, am I correct assuming it will also move to XAPI?

Regards,

-Tino

--
Constantino Vázquez Blanco, MSc
OpenNebula Major Contributor  / Cloud Researcher
www.OpenNebula.org | @tinova79



On Wed, Feb 2, 2011 at 10:55 AM, Ian Campbell <Ian.Campbell@citrix.com> wrote:
> On Wed, 2011-02-02 at 05:08 +0000, Todd Deshane wrote:
>> On Tue, Feb 1, 2011 at 1:25 PM, Tino Vazquez <tinova@opennebula.org> wrote:
>> >  * At the moment, ONE creates a text file that describes the VM in
>> > terms that Xen understands, and this is processed by the "xm" command.
>>
>> XCP has a near equivalent with the xl command, which uses the libxl
>> backend. Backwards compatibility (with the exception of being able to
>> use arbitrary python code embedded) is the goal.
>
> XCP does not currently include a version of Xen which includes xl or
> libxl. Even in the future when it does xl will be there only as a
> debugging aid for developers and will not be a supported mechanism for
> interacting with an XCP host.
>
> The XCP toolstack is xapi -- the supported way of interacting with XAPI
> host is via the XenAPI XML/RPC mechanism.
>
> One day we hope xapi will also use libxl, but this is not the same as
> using xl which is a different toolstack designed to provide
> compatibility with xend.
>
>> > In XCP, there is a "xe" command with a completely different set of
>> > options.
>
> "xe" is a command line client which speaks the XenAPI XML/RPC protocol
> (modulo some uninteresting implementation details)
>
>>  The question is: can the same text file be used to launch a
>> > VM in XCP? Or the approach must be something different, using the
>> > functionality offered by "xe" or by XAPI?
>
> Integrating with XenAPI is the right way to integrate with XCP. In
> general I think it would be recommended that something like OpenNebula
> integration uses the XML/RPC interface directly rather than forking xe
> and parsing the results.
>
> Ian.
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>

Re: [Xen-devel] About XCP OpenNebula integration

[Stefano Stabellini]

On Fri, 4 Feb 2011, Tino Vazquez wrote:
> Another question regarding the Xen standalone, since "xend" is going
> away, am I correct assuming it will also move to XAPI?

As I have written in my other email, xen standalone is moving to "xl"
that is a very small and lightweight "xm" replacement.
Theoretically porting OpenNebula to "xl" should be very easy because
"xl" should be command line compatible with "xm". However few
differences between the two tools exist, so I expect some changes to be
needed.
I am keen on having OpenNebula run on "xl", if you need any help please
let us know.

Re: XL and OpenNebula (was: About XCP OpenNebula integration)

[Stefano Stabellini]

Excuse me because I am about to redirect this thread to a different
topic that has nothing to do with XCP.

On Tue, 1 Feb 2011, Tino Vazquez wrote:
> Dear list,
> 
> We (the OpenNebula Team) are very interested in integrating OpenNebula
> with XCP. At the moment, OpenNebula can interface with the Xen
> hypervisor, but since XCP appears to be much more than just Xen, I
> would like to ask a couple of questions to the XCP developers in order
> to define the direction we may take on this integration.
> 
>  * At the moment, ONE creates a text file that describes the VM in
> terms that Xen understands, and this is processed by the "xm" command.
> In XCP, there is a "xe" command with a completely different set of
> options. The question is: can the same text file be used to launch a
> VM in XCP? Or the approach must be something different, using the
> functionality offered by "xe" or by XAPI?
> 

The coming 4.1 open source Xen release (we are in RC3 now) ships with a
new toolstack called xl, that tries to be command line compatible with
xm, but there are few significant differences:

- there is no support for embedded python in VM config files;

- there is no support for managed domains (domains you can install on
a host and list even if they are not running);

- there is no XML-RPC interface.

Apart from these issues everything else should work as before.

Do you think you'll be able to adapt OpenNebula to use the new
toolstack? If you don't use the features above it shouldn't take much
more than ln -s xm xl.
It is worth mentioning that xend and xm are still available in the 4.1
release, just not recommended anymore.


P.S.
you may understand now what the confusion was about: XCP has a different
toolstack called xapi, it doesn't use xend at all. However XCP has a copy
of xl for debugging purposes, but it shouldn't be used for anything but
debugging on a XCP system. So if you want to integrate XCP into
OpenNebula you should use the appropriate RPC calls supported by xapi.