Home

VirtualBox fencing and Red Hat Enterprise Linux Cluster Suite

I know there is already a perl script to fence VirtualBox machines, but since I am not very familiar with Perl, a shell scripts seemed easier.

So; when you run VirtualBox and would like (virtual) cluster nodes to be able to fence, you may use this shell script on the virtual machines:

#!/bin/sh -x

# Script to stop and start a virtual machine.
# The only required argument is machinename.

eval $(cat -)

# I use Apple Mac OS X, but any OS may be used.
vboxmanage="/Applications/VirtualBox.app/Contents/MacOS/VBoxManage"

usage () {
/bin/echo "Usage: $0 -a NAME [-o ACTION]"
/bin/echo
/bin/echo " -a NAME"
/bin/echo "   The name of the virtual machine to be fenced."
/bin/echo "   In case it contains spaces, use double quotes."
/bin/echo " -o ACTION"
/bin/echo "   What to do; start|stop|reboot(default)."
/bin/echo
exit 1
}

while [ "$#" -gt 0 ] ; do
case "$1" in
  -a)
   if [ "$2" ] ; then
    vm="$2"
    shift ; shift
   else
    /bin/echo "Missing value for $1."
    /bin/echo
    usage
    shift
   fi
  ;;
  -o)
   if [ "$2" ] ; then
    action="$2"
    shift ; shift
   else
    /bin/echo "Missing value for $1."
    /bin/echo
    usage
    shift
   fi
  ;;
  *)
   /bin/echo "Not a know option, $1."
   usage
   shift
  ;;
esac
done

if [ ! "${action}" ] ; then
action=reboot
fi

if [ ! "${vm}" ] ; then
/bin/echo "Error, please specify a name."
usage
fi

check() {
ssh $host "$vboxmanage showvminfo ${vm}" > /dev/null 2>&1
if [ ${?} != 0 ] ; then
  /bin/echo "Error, VM ${vm} not found, choose one of these:"
  ssh $host "$vboxmanage list vms | sed 's/" .*/"/'"
  exit 1
fi
}


stop() {
ssh $host "$vboxmanage controlvm ${vm} poweroff > /dev/null 2>&1"
}

start() {
ssh $host "$vboxmanage startvm ${vm} > /dev/null 2>&1"
}

reboot() {
stop
sleep 3
start
}

case $action in
start)
  check
  start
;;
stop)
  check
  stop
;;
reboot)
  check
  reboot
;;
*)
  /bin/echo "Unknown action: $action"
  /bin/echo
  usage
;;
esac

To use this script, add this block to every "clusternode" in /etc/cluster/cluster.conf:

    <fence>
        <method name="1">
            <device host="robertdebock@clustermember2.example.com" name="vbox" vm="ClusterMember2"/>
        </method>
    </fence>

And create a shared fence device in /etc/cluster/cluster.conf:

    <fencedevices>
        <fencedevice agent="fence_vbox" name="vbox"/>
    </fencedevices>

The important variables are "host" and "vm". "host" is used to connect to the physical box running VirtualBox, "vm" is the actual name of the virtual machine, as displayed by VirtualBox.