Re: [vserver] Guests using X with X Server on Host

From: Thomas Weber <>
Date: Thu 31 Jan 2008 - 13:34:33 GMT
Message-Id: <1201786473.5205.55.camel@utumno>

Am Donnerstag, den 31.01.2008, 13:52 +0100 schrieb Oliver Welter:
> Hi Tom,
> Thomas Weber wrote:
> >> ok bit than I need a way to pipe the output from xvfb to the hosts X
> >> there a way to do ?
> >
> > Is it possible that you're mixing up Server and Client regarding X11?
> > The Server is the 'thing' (usually Keyboard, Mouse, Display) that
> > displays 'stuff' the Clients (programs that want output/input to/from
> > the Server) request.
> > So your GUI to the app would be the Client. Just give it something like
> > Xvfb as Server (maybe via the DISPLAY environment Variable) and it will
> > draw it's interface on the Xvfb Server (which is kind of a display in
> > RAM). Now, on the same Xvfb Server setup a vncserver to which your
> > client can connect to. No need to deal with the hosts hardware.
> To connect the application (inside the vserver guest) to the xvfb, it
> must be running inside the guest. And as far as I tried, I have to kick
> up the vncserver also in the guest which would require to bring up a
> vncserver in every guest.
> The preferred solution for me would be (I guess that it does not work) a
> vncserver running on the host machine, where the customer conntects to
> from his Windows desktop using vncviewer. I give him a desktop-icon that
> opens a bash inside the vserver guest and if he now launches
> "./app-config" from a terminal, the app-config GUI should appear on the
> screen.

This could also be done - if you don't mind that anyone with access to
the one vncserver hast access to any vserver.

> As I guess this wont work without a full blown server inside the guest,
> I would accept, if he enters the server via SSH and afterwards connects
> to the box so he directly has a desktop running inside the guest.

There is no need to have an X Server running at all on the same host or
vserver that runs the client (your GUI).
So in your case you might want to setup one vserver which hosts an X
Server realized via Xfvb + a running vncserver. Now configure all the
gui-frontends in your various vservers to display ont that one X Server
(set DISPLAY environment in the clients and grant access on the X
server) and every single vserver instance will display on one (virtual)
screen wich you can access via vnc.

Doing X11 redirection via ssh wouldn't require an running Xserver on
that host or the vservers at all. Just the box that connects via ssh
would need a running XServer. The realworldclient connecting would have
to run the Xserver so that your gui could connect to it as Xclient -
pretty easy to mix up.

> The main pinpoint is: The app itsself needs nearly no resources and
> kicking up an X server inside each guest will need more resources than
> the whole rest of the guest, so I want to avoid this.

An Xserver itself, like Xvfb in lowres, probably needs less ressources
than you might think at the moment. The bloat comes with GNOME, KDE etc
that you put on top of it. Nonetheless i wouldn't want an Xvfb running
in all my vservers.

You seem to have a (very common) misunderstanding of what X11 is and how
it works (basically just a network protocol). Please look it up first -
wikipedia should give a good glue.


ps: isn't that off topic already?
Received on Thu Jan 31 13:40:00 2008

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