[libvirt] [PATCH] qemu: configurable VNC port boundaries for domains

[Daniel P. Berrange]

On Tue, May 22, 2012 at 01:22:16PM -0400, Dave Allan wrote:
> On Tue, May 22, 2012 at 09:09:55AM -0600, Eric Blake wrote:
> > On 05/22/2012 09:00 AM, Dave Allan wrote:
> > > On Tue, May 22, 2012 at 04:10:03PM +0200, Martin Kletzander wrote:
> > >> The defines QEMU_VNC_PORT_MIN and QEMU_VNC_PORT_MAX were used to find
> > >> free port when starting domains. As this was hardcoded to the same
> > >> ports as default VNC servers, there were races with these other
> > >> programs. This patch includes the possibility to change the default
> > >> starting port as well as the maximum port in qemu config file.
> > > 
> > > Hi Martin,
> > > 
> > > Two design comments:
> > > 
> > > 1) https://bugzilla.redhat.com/show_bug.cgi?id=782814 requests that
> > > the default port be changed to avoid conflicts, which seems reasonable
> > > to me.
> > 
> > If we choose better defaults for new installations, we still need to
> > worry about preserving existing ranges when upgrading old installations.
> >  This may need some coordination with the spec file doing some %post
> > magic to add in vnc_port_min with a value other than 5900 to qemu.conf
> > on new installations, but leaving it unspecified when doing an upgrade.
> 
> That's a good point, we certainly don't want to break things on
> upgrade.  At least one case that would is where people have opened the
> old range in a firewall, and now instead of ports, say, 5900-n, now
> people will be getting some other range.
> 
> > > 2) I agree with the config option since most applications on the
> > > system will want the system defaults.  However, IMO in this case an
> > > application writer should be given the option in the XML to override
> > > the system default.
> > 
> > Agreed - I think we need both solutions - qemu.conf to specify the
> > default range, and per-domain XML to specify an override (does the XML
> > need to specify a range, or just a single port?).
> 
> I think a range, like the config option.

I think this is unneccessary configurability. A qemu config option is
sufficient.  I just don't see any application wanting to set different
default ranges per guest.

Daniel
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