#!/bin/sh

# zfsync: sync zfs pool(s) between two servers

# in case of failure, unepexpected reboot while syncing, etc.:
# - destroy all snapshots on both local & ${bro}
# - for i in ftp web mail; do zfs send servers/$i/home@newsync | ssh ${bro} zfs receive -vFd servers ;done
# - for i in ftp web mail; do zfs rename servers/$i/home@newsync servers/$i/home@prevsync ;done
# - ssh ${bro} "for i in ftp web mail; do zfs rename servers/$i/home@newsync servers/$i/home@prevsync ;done"

bro="small"
pools="ftp mail web"

SENDNSCA=/usr/local/sbin/send_nsca\ -H\ <nagios_host>\ -d\ ';;'\ -c\ /usr/local/etc/nagios/send_nsca.cfg
HOSTNAME=`/bin/hostname -f | /usr/bin/cut -d '.' -f 1,1`
SERVICENAME=zfsync
LOGFILE=/tmp/zfsync.log
sync_success=1

alert()
{
	echo "${HOSTNAME};;${SERVICENAME};;2;CRITICAL - ZFS Sync failed at `date`, please check ${LOGFILE} for complete report." | ${SENDNSCA} >/dev/null
	exit $?
}
if [ $1 ]
then
if [ $1 = "init" ]
then
echo "`date`: ZFSync INIT starting."
	echo "wiping previous syncs"
	for snapshot in `zfs list -t snapshot -o name | grep -e prevsync -e newsync`; do zfs destroy $snapshot ; done
	ssh -q ${bro} 'for snapshot in `zfs list -t snapshot -o name | grep -e prevsync -e newsync`; do zfs destroy $snapshot ; done'
	echo "making full snapshots"
	for jail in $pools; do zfs snapshot servers/$jail/home@newsync;done
	echo "sending full snapshots"
	for jail in $pools; do zfs send servers/$jail/home@newsync | ssh -q ${bro} 'zfs receive -vFd servers' ;done
	echo "renaming them to use them as a base for diff snapshots"
	for jail in $pools; do zfs rename servers/$jail/home@newsync servers/$jail/home@prevsync ;done
	ssh -q ${bro} 'for jail in ftp mail web; do zfs rename servers/$jail/home@newsync servers/$jail/home@prevsync ;done'
	exit $?
fi
fi

echo "`date`: ZFSync starting."
for pool in $pools
do
	dataset="servers/${pool}/home"
	echo "making new snapshot for ${pool}"
	zfs snapshot ${dataset}@newsync || alert
	echo "sending snapshot"
	zfs send -i prevsync ${dataset}@newsync | ssh -q ${bro} "zfs receive -vFd servers" || alert
	echo "cleaning"
	zfs destroy ${dataset}@prevsync || alert
	zfs rename ${dataset}@newsync ${dataset}@prevsync || alert
	ssh -q ${bro} "zfs destroy ${dataset}@prevsync && zfs rename ${dataset}@newsync ${dataset}@prevsync" || alert
done

echo
echo "${HOSTNAME};;${SERVICENAME};;0;OK - ZFS Sync succeeded at `date`" | ${SENDNSCA} >/dev/null