[libvirt] [PATCH] RFC: experimental libvirtd upstart job

[Daniel P. Berrange]

On Fri, Feb 18, 2011 at 03:48:29PM -0600, Serge E. Hallyn wrote:
> Quoting apevec at gmail.com (apevec at gmail.com):
> > From: Alan Pevec <apevec at redhat.com>
> > 
> > To install it, disable libvirtd sysv initscript:
> >     chkconfig libvirtd off
> >     service libvirtd stop
> > 
> > and enable libvirtd upstart job:
> >     cp  /usr/share/doc/libvirt-*/libvirtd.upstart \
> >         /etc/init/libvirtd.conf
> >     initctl reload-configuration
> >     initctl start libvirtd
> > 
> > Test:
> >     initctl status libvirtd
> > libvirtd start/running, process 3929
> >     killall -9 libvirtd
> >     initctl status libvirtd
> > libvirtd start/running, process 4047
> > ---
> >  daemon/Makefile.am      |    1 +
> >  daemon/libvirtd.upstart |   47 +++++++++++++++++++++++++++++++++++++++++++++++
> >  libvirt.spec.in         |    1 +
> >  3 files changed, 49 insertions(+), 0 deletions(-)
> >  create mode 100644 daemon/libvirtd.upstart
> > 
> > diff --git a/daemon/Makefile.am b/daemon/Makefile.am
> > index cdf0f75..a4ebcf8 100644
> > --- a/daemon/Makefile.am
> > +++ b/daemon/Makefile.am
> > @@ -27,6 +27,7 @@ EXTRA_DIST =						\
> >  	remote_generate_stubs.pl			\
> >  	libvirtd.conf					\
> >  	libvirtd.init.in				\
> > +	libvirtd.upstart				\
> >  	libvirtd.policy-0				\
> >  	libvirtd.policy-1				\
> >  	libvirtd.sasl					\
> > diff --git a/daemon/libvirtd.upstart b/daemon/libvirtd.upstart
> > new file mode 100644
> > index 0000000..40d5fa3
> > --- /dev/null
> > +++ b/daemon/libvirtd.upstart
> > @@ -0,0 +1,47 @@
> > +# libvirtd upstart job
> > +#
> > +# XXX wait for rc to get all dependent initscripts started
> > +# from sysv libvirtd initscript: Required-Start: $network messagebus
> > +start on stopped rc RUNLEVEL=[345]
> > +stop on runlevel [016]
> > +respawn
> > +# default rate limit is 10x/5s
> > +#respawn limit 10 5
> > +
> > +# DAEMON_COREFILE_LIMIT in /etc/sysconfig/libvirtd doesn't have effect
> > +# must set resource limits here
> > +#limit core unlimited unlimited
> > +
> > +# documented http://upstart.ubuntu.com/wiki/Stanzas#pid
> > +# but not accepted by upstart-0.6.5
> > +#pid file /var/run/libvirtd.pid
> > +
> > +env PIDFILE=/var/run/libvirtd.pid
> > +
> > +script
> > +	LIBVIRTD_CONFIG=
> > +	LIBVIRTD_ARGS=
> > +	KRB5_KTNAME=/etc/libvirt/krb5.tab
> > +	
> > +	test -f /etc/sysconfig/libvirtd && . /etc/sysconfig/libvirtd
> > +	
> > +	export QEMU_AUDIO_DRV
> > +	export SDL_AUDIODRIVER
> > +	
> > +	LIBVIRTD_CONFIG_ARGS=
> > +	if [ -n "$LIBVIRTD_CONFIG" ]
> > +	then
> > +		LIBVIRTD_CONFIG_ARGS="--config $LIBVIRTD_CONFIG"
> > +	else
> > +		true
> > +	fi
> > +	
> > +	mkdir -p /var/cache/libvirt
> > +	rm -rf /var/cache/libvirt/*
> > +	KRB5_KTNAME=$KRB5_KTNAME /usr/sbin/libvirtd $LIBVIRTD_CONFIG_ARGS $LIBVIRTD_ARGS
> > +end script
> > +
> > +post-stop script
> > +	rm -f $PIDFILE
> > +	rm -rf /var/cache/libvirt/*
> > +end script
> 
> Hi,
> 
> If you're using upstart, then why use your own pidfile? FWIW, attached is
> the upstart script used in Ubuntu:
> 
> =============================================
> description "libvirt daemon"
> author "Dustin Kirkland <kirkland at canonical.com>"
> 
> start on runlevel [2345]
> stop on runlevel [!2345]
> 
> expect daemon
> respawn
> 
> env libvirtd_opts="-d"
> env start_libvirtd="yes"
> pre-start script
> 	[ -r /etc/default/libvirt-bin ] && . /etc/default/libvirt-bin
> 	[ ! "x$start_libvirtd" = "xyes" ] && { stop; exit 0; }
> 	mkdir -p /var/run/libvirt
> 	# Clean up a pidfile that might be left around
> 	rm -f /var/run/libvirtd.pid
> end script
> 
> # If you used to set $libvirtd_opts in /etc/default/libvirt-bin,
> # change the 'exec' line here instead.
> exec /usr/sbin/libvirtd $libvirtd_opts
> =============================================
> 
> In order to play nicely with libcgroup, we're also testing
> the following job to ship with libcgroup:
> 
> =============================================
> # libvirt-cgred-wait
> start on starting libvirt-bin
> stop on started cgred or stopped cgred
> 
> task
> normal exit 2
> script
>   status cgred | grep -q "start/running" && exit 0
>   start cgred || true
>   sleep 3600
> end script
> =============================================

FYI, libvirt has no need for the  cgred to be present / running, and
indeed if you're not careful with the rules you create for cgred it
could really mess things up by moving VM proceses to a different
cgroup behind libvirt's back.

For cgroups integration, libvirt merely requires that something has
mounted the various cgroups controllers. The can be mounted in any
location, and with any combination of controllers. libvirtd will
detect what cgroups it is located in at startup, and create its
own cgroups below these points in the hierarchy.

On Fedora we do this with the 'cgconfig' init script which more or
less just runs  'cgconfigparse -l /etc/cgconfig.conf' to mount the
bits

Regards,
Daniel
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