Re: [Libvir] Restarting of libvirt_qemud daemon

Daniel P. Berrange wrote: > On Fri, Mar 09, 2007 at 10:47:18AM +0000, Richard W.M. Jones wrote: >> Daniel P. Berrange wrote: >>> Thinking about later RPM upgrades I think we need to think about >>> whether it >>> will be possible to restart the libvirt_qemud while guests & >>> networks are >>> running. There's a couple of issues: >>> >>> - We do waitpid() to cleanup qemu & dnsmasq processes when we stop >>> domains >>> & networks, or to detect when they crash. For the former, we could >>> may >>> they daemons to avoid waitpid() cleanup, but we'd still need >>> waitpid to >>> be able to detect shutdowns. There is also the issue of enumerating >>> running instances. >> Maybe I'm missing something big here, but how would libvirt_qemud >> regain connections to the running qemu monitor ptys? > > That's one of the challenges to be addressed :-) Fortunately the monitor > is set to be exposed via /dev/pty/XXX, so if the restarted client can > find out the path to the PTY, then it can re-open it. Maybe we just need > to record a state file somewhere containing a PID & PTY path. Is it possible to start qemu with something like: qemu -monitor pipe:/var/some/known/place/pipe.UUID and then just look in /var/some/known/place/ in order to find the running instances?