What's the Pre-requisites for virt-manager

On Fri, Nov 24, 2006 at 10:52:13AM +0800, Henry Zhang wrote:
> 
> Thanks Dan, please see comments below.. 
> 
> Daniel P. Berrange ??????:
> >On Thu, Nov 23, 2006 at 07:54:24PM +0800, Henry
Zhang wrote:
> >  
> >>hi Daniel,
> >>
> >>From the webpage, I can see that dbus and
gnome-python-desktop are 
> >>optional, but when our release engineer try to
build, seems they are 
> >>not, so could you confirm me if we can
build/run virt-manager correctly 
> >>without Dbus?
> >>    
> >
> >Ah, I should perhaps clarify that a little. The
DBus python libraries
> >are required to be present, but you don't have to
have DBus running.
> So can I say: Dbus is necessary one for building
virt-manager, while not 
> when running it?

The DBus python libraries *are* needed at runtime. If the
DBus daemon isn't
present though, we catch the connection failure and disable
that piece of
the virtmanager functionality on the fly.

> > If it fails to connect to the DBus daemon, the app
will log a warning and
> >continue.  The GNome Python Desktop stuff is
competely optional - if you
> >don't have the python bindings installed it will
simply disable the VNC
> >password saving altogether.
> >
> >  
> >>I carefully read the content in "Dbus
Services", My understanding is 
> >>that Dbus in virt-manager is used to make other
external application 
> >>call some core function, so that they can get
display the window/dialog .
> >>When Dbus is used?
> >>
> >>"The remote control module provides the
DBus service 
> >><http://virt-manager.et.redhat.com/dbusservice.html>
allowing various UI 
> >>functions to be controlled remotely.": My
understanding for "remotely" 
> >>is to run virt-manager remotely, is it correct?
so will dbus only used 
> >>when remotely? if some application in local
machine, it may also use 
> >>Dbus to run some function?
> >>    
> >
> >Not quite - the intent with the DBus stuff is that
if you run two copies
> >of virt-manager on the same machine, 
> For "two copies of virt-manager": my
understanding is:
> Case 1: when I login, and run %/usr/binvirt-manager,
then when I run 
> %/usr/bin/virt-manager in the same machine again,
> the second one is the copy of first one, and just use
DBus/RPC to call.

Yes, the first copy you run of 'virt-manager' pops up the
window directly.
The second concurrent copy will send a DBus message to the
first, asking
it to popup a particular window, and then the second copy
exits - since the
first copy is dealing with it now.

> Case2: When I login machine A, run
%/usr/binvirt-manager, then remotely 
> access machine A through machine B,
> and run %/usr/bin/virt-manager again, so in this case,
the second one is 
> the copy of the first one, and use Dbus/RPC.

In most cases the DBus daemon is only available if you are
logged into
a local X / GNOME desktop session. If you are ssh'ing into a
machine
remotely it typically won't have  DBus session available.
So, when DBus
isn't available, many copies of virt-manager will be
launched and have
no way to detect that another copy is already running.

When the DBus folks get the DBus connection automatically
forwarding
over SSH, in the same way that X11 is forwarded, then the
remote case
will work in same way as local case. I've no idea when
that'll be
made to work though.

Regards,
Dan.
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What's the Pre-requisites for virt-manager

Thread: What's the Pre-requisites for virt-manager