Set debian boxes network hwaddr

Required by failback mechanism used to fetch container ip based on dnsmasq leases

boxes/debian/lxc-template

@@ -152,6 +152,15 @@ copy_configuration()
     rootfs=$2
     name=$3
 
+    # if there is exactly one veth network entry, make sure it has an
+    # associated hwaddr.
+    nics=`grep -e '^lxc\.network\.type[ \t]*=[ \t]*veth' $path/config | wc -l`
+    if [ $nics -eq 1 ]; then
+        grep -q "^lxc.network.hwaddr" $path/config || cat <<EOF >> $path/config
+lxc.network.hwaddr = 00:16:3e:$(openssl rand -hex 3| sed 's/\(..\)/\1:/g; s/.$//')
+EOF
+    fi
+
     grep -q "^lxc.rootfs" $path/config 2>/dev/null || echo "lxc.rootfs = $rootfs" >> $path/config
     cat <<EOF >> $path/config
 lxc.tty = 4