[kernel-xen] Test init script for Xen 4.1.2

[Steven Haigh]

Hi all,

I have attempted a re-write of the xendomains init script to interpret a 
few things better and hopefully allow me to move away from lock files 
for starts DomUs which the original does not track correctly.

As 'xm create blah' does not create a lock file, sometimes the original 
initscript does not correctly shutdown or save running domains that are 
not started at boot.

I have attached the script for testing (please back up the original 
first!). It should be dropped into /etc/init.d

Please post feedback to the list!

-- 
Steven Haigh

Email: netwiz at crc.id.au
Web: http://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897
Fax: (03) 8338 0299
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#!/bin/bash
#
# /etc/init.d/xendomains
# Start / stop domains automatically when domain 0 boots / shuts down.
#
# chkconfig: 345 99 00
# description: Start / stop Xen domains.
#
# Re-written from scratch by Steven Haigh <netwiz at crc.id.au> for EL6 as stock
# script has a lot of problems. May work on other distros, YMMV.
#
### BEGIN INIT INFO
# Provides:          xendomains
# Required-Start:    $syslog $remote_fs xenstored xenconsoled
# Should-Start:      xend
# Required-Stop:     $syslog $remote_fs xenstored xenconsoled
# Should-Stop:       xend
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: Start/stop secondary xen domains
# Description:       Start / stop domains automatically when domain 0 
#                    boots / shuts down.
### END INIT INFO

## Check to see what we use to communicate with the hypervisor - xm or xl
## We will prefer xm, but fall back to xl if we have to. Exit if none work.
CMD=`which xm`
if [ -x $CMD ]; then
	$CMD list &> /dev/null
	if test $? -ne 0; then
		CMD=`which xl`
		$CMD list &> /dev/null
		if test $? -ne 0; then
			echo "Couldn't find a usable xl or xm. Bailing..."
			exit 0
		fi
	fi
fi

## Check to see if we're running as Dom0. If so, the following file should
## exist.
if ! [ -e /proc/xen/privcmd ]; then
	echo "Not running as Domain0. Exiting..."
	exit 0
fi

## Load the xendomains options, bailing if we can't.
if [ -r /etc/sysconfig/xendomains ]; then
	. /etc/sysconfig/xendomains
else
	echo "/etc/sysconfig/xendomains not found or unreadable. This is an issue. Exiting..."
	exit 0
fi

if [ -d /var/lock/subsys ]; then
	LOCKFILE=/var/lock/subsys/xendomains
else
	LOCKFILE=/var/lock/xendomains
fi

## Source function library.
. /etc/init.d/functions

get_domu_name() {
	DOMU_NAME=$($CMD create --quiet --dryrun --defconfig "$1" | sed -n 's/^.*(name \(.*\))$/\1/p')
}

watchdog() {
	## Launch a command and wait until the timeout before killing forcefully.
	for WAIT in `seq 0 $XENDOMAINS_STOP_MAXWAIT`; do
		RESULT=`ps -p $PID`
		if [ $? -eq 1 ]; then
			success
			break
		fi
		echo -n "."
		sleep 1
	done
	RESULT=`ps -p $PID`
	if [ $? -eq 0 ]; then
		warning
		kill $PID
	fi
	echo
}

start() {
	touch $LOCKFILE

	## Check to see if we should restore saved DomUs on start
	## Also check if the restore directory actually exists.
	if [ "$XENDOMAINS_RESTORE" = "true" ] && [ -d $XENDOMAINS_SAVE ] && [ -n "$XENDOMAINS_SAVE" ]; then
		for DOMU in $XENDOMAINS_SAVE/*; do
			if [ -r $DOMU ]; then
				HEADER=`head -c 16 $DOMU | head -n 1 2> /dev/null`
				if [ "$HEADER" = "LinuxGuestRecord" ] || [ "$HEADER" = "Xen saved domain" ]; then
					echo -n "Restoring Xen Domain ${DOMU##*/}"
					RESULT=`$CMD restore $DOMU 2>&1 1>/dev/null`
					if [ $? -ne 0 ]; then
						failure
					else
						success
					fi
					rm -f "$DOMU"
					echo
				fi
			fi
		done
	fi

	## Check to see if our autostart directory exists and is actually set.
	if [ -d $XENDOMAINS_AUTO ] && [ -n $XENDOMAINS_AUTO ]; then
		## Start each domain in our autostart directory.
		for DOMU in $XENDOMAINS_AUTO/*; do
			get_domu_name $DOMU
			echo -n $"Starting Xen auto domain $DOMU_NAME: "
			
			## Check if domain is already running.
			RESULT=`$CMD list $DOMU_NAME >& /dev/null`
			if [ $? -eq 0 ]; then
				## DomU is already running.
				echo -n " (Skipped - Already running)"
			else
				## Start the DomU...
				RESULT=`$CMD create $DOMU >& /dev/null`
				if [ $? -eq 0 ]; then
					usleep $XENDOMAINS_CREATE_USLEEP
					success
				else
					failure
				fi
			fi
			echo
		done
	fi

	return 0
}

stop() {
	## Check to see if we should send a SysRq to the DomUs
	if [ -n "$XENDOMAINS_SYSRQ" ]; then
		IFS=$'\n'
		echo -n "Sending SYSRQs to Xen Domains:"
		for DOMU in `$CMD list | tail -n +3 | sort`; do
			unset IFS
			DOMU_NAME=`echo "$DOMU" | awk '{ print $1 }'`
			for sysrq in $XENDOMAINS_SYSRQ; do
				$CMD sysrq $DOMU_NAME $sysrq
				echo -n "."
			done
		done
		success
		echo
	fi

	## Check to see if we should migrate running domains...
	if [ -n "$XENDOMAINS_MIGRATE" ]; then
		## We should be doing a migrate. We don't really do much, just pass the
		## values to XM/XL - if it fails, save or shutdown can have a go.
		IFS=$'\n'
		for DOMU in `$CMD list | tail -n +3 | sort`; do
			unset IFS
			DOMU_NAME=`echo "$DOMU" | awk '{ print $1 }'`
			echo -n "Migrating Xen domain $DOMU_NAME:"
			$CMD migrate $DOMU_NAME $XENDOMAINS_MIGRATE 2>&1 1>/dev/null &
			PID=$!
			watchdog
		done
	fi

	## Check to see if we are to save domains...
	if [ -d $XENDOMAINS_SAVE ] && [ -n "$XENDOMAINS_SAVE" ]; then
		## Cycle through the domains running and do what we need to do.
		IFS=$'\n'
		for DOMU in `$CMD list | tail -n +3 | sort`; do
			unset IFS
			DOMU_NAME=`echo "$DOMU" | awk '{ print $1 }'`
	
			## Now we set our ionice to lower than realtime as we don't want the
			## system to become unresponsive while saving a DomU. It still may
			## need to fulfil requests from other DomUs etc.
			ionice -c 2 -n 7 -p $$

			echo -n "Saving Xen Domain $DOMU_NAME:"
			$CMD save $DOMU_NAME $XENDOMAINS_SAVE/$DOMU_NAME > /dev/null 2>&1 &
			PID=$!
			watchdog
		done
	fi

	## Shut down the remaining domains...
	if [ -n "$XENDOMAINS_SHUTDOWN" ]; then
		IFS=$'\n'
		for DOMU in `$CMD list | tail -n +3 | sort`; do
			unset IFS
			DOMU_NAME=`echo "$DOMU" | awk '{ print $1 }'`
			echo -n "Shutting down $DOMU_NAME:"
			$CMD shutdown $DOMU_NAME $XENDOMAINS_SHUTDOWN 2>&1 1>/dev/null &
			PID=$!
			watchdog
		done
	fi
	
	rm -f $LOCKFILE
	return 0
}

status() {
	## We've already passed the test to see if Xen Dom0 is running, so here
	## we check the number of lines returned from a list command and minus
	## 2 from it (Header + Domain-0) and also some memory stats.
	NUM_DOMU=$((`$CMD list | wc -l`-2))
	MEM_FREE=`$CMD info | grep free_memory | cut -f2 -d":"`
	MEM_TOTAL=`$CMD info | grep total_memory | cut -f2 -d":"`
	echo "Xen running with $NUM_DOMU DomUs.$MEM_FREE MB of$MEM_TOTAL MB free."
	return 0
}

case "$1" in
    start)
        start
        RETVAL=$?
        ;;
    stop)
        stop
        RETVAL=$?
        ;;
    status)
        status
        RETVAL=$?
        ;;
    restart)
	stop
	start
	;;
esac