pxe-vm.sh

#!/bin/bash

MEM=512
LAN=eth0
BRIDGE=virtbr


# runs under the user that started it. make sure it has access to /dev/kvm
function start_vm {
    TAPIF=$1
    shift
    /usr/bin/qemu-system-i386 -enable-kvm -m $MEM -net nic -net tap,ifname=$TAPIF,script=no,downscript=no -boot n "$@"
}

# runs under sudo
function setup_net {
  TAPIF=$1
  USER=$2
  ip tuntap add dev $TAPIF mode tap user $USER
  brctl addbr $BRIDGE &> /dev/null
  brctl addif $BRIDGE $LAN &> /dev/null
  brctl addif $BRIDGE $TAPIF
  ip link set $BRIDGE up
  ip link set $LAN up
  ip link set $TAPIF up
}

# runs under sudo
function reset_net {
  TAPIF=$1
  ip link set $TAPIF down
  brctl delif $BRIDGE $TAPIF
  ip tuntap del dev $TAPIF mode tap
}

case "$RUN_FUNC" in

    "")
        # find out how to dynamically set the tap interface name, for now use "virttap"
        TAPIF=virttap
        sudo RUN_FUNC=_setup_net_ $0 $TAPIF `id -u`
        start_vm $TAPIF "$@"
        sudo RUN_FUNC=_reset_net_ $0 $TAPIF
        ;;

    "_setup_net_")
        setup_net "$@"
        ;;

    "_reset_net_")
        reset_net "$@"
        ;;

esac