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Re: [Libvir] Get info with libvirt from a remote Xen dom0



On Mon, Jan 08, 2007 at 11:08:34PM +0100, Jordi Prats wrote:
> Hi,
> On the function:
>
> virConnectPtr virConnectOpenReadOnly  (const char * name)
>
> name is unused. Is planned any use for it? I'm particullay interested on
> obtaining information from a remote machine.
>
> I'm trying to provide HA between dom0, so this way is a dom0 chashes
> another dom0 will create every vm from the othe node.
>
> Example:
>
> dom0.1 have vm01 and vm02
> dom0.2 have vm03 and vm04
>
> Then if dom0.1 goes down, dom0.2 will have vm01,vm02,vm03 and vm04
> 
> I'm pretending to use libvirt as a abstraction layer to operate this Xen
> cluster.

  Right, basically this is not well documented because we are not 100% sure
on how this facility will evolve but there is some support for remote
access at least for Xend usage. This requires to have Xend remote http
access activated on the target machines dom0.1 and dom0.2. For this you
need to edit /etc/xen/xend-config.sxp to set up
  (xend-http-server yes)
see also
  #(xend-port            8000)
and restart xend on the machines.
Then the xend back-end of libvirt will be able to talk to the remote
machine by giving the URL
   "http://dom0.1:8000/";
as the name parameter when opening the ReadOnly connection.
Since there is no authentication this is completely insecure, and the xend
server will take and execute *any* request coming from the remote HTTP
interface, in that case I suggest to add specific firewall rules on the
Dom0 domains to restrict access to that port to only the machines which needs
it (and in general never open the http server up on an untrusted network
you're warned :-).

  If the virConnectOpenReadOnly call succeed then you should be all set.
Note that one program may monitor multiple machines that way by opening
one connection per node.

  Once we are a bit more confident on the long term I will add a page about
remote support in libvirt, but I guess we need first more experience with
different virtualization back end before selecting a final URI pattern for
the name value of the Open and OpenReadOnly calls, for now we will stick
to purely the "http" scheme and xend access.

Daniel

-- 
Red Hat Virtualization group http://redhat.com/virtualization/
Daniel Veillard      | virtualization library  http://libvirt.org/
veillard redhat com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
http://veillard.com/ | Rpmfind RPM search engine  http://rpmfind.net/


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