#!/bin/sh

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

# before first use, or in case of failure, unexpected reboot while syncing, etc.:
#
# launch "zfsync.sh init"
#
# or manually:
#
# - destroy all snapshots on both local & ${bro}
# - for i in ftp web mail; do zfs snapshot servers/$i/home@newsync ;done
# - 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'
#
# once init is done, call it using crontab:
# */10    *       *       *       *       root    nice -n 19 /usr/local/bin/zfsync.sh >/tmp/zfsync.log


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

SENDNSCA=/usr/local/sbin/send_nsca\ -H\ 192.168.X.X\ -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
LOCKFILE=/tmp/zfsync.lock
ZROOT=zdata/servers
sync_success=1

if [ -e $LOCKFILE ]
then
	echo "ERROR: $0 is already running with pid `cat $LOCKFILE`, check $LOCKFILE"
	exit 1
fi
echo ${$}>$LOCKFILE

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 $ZROOT/$jail/home@newsync;done
	echo "sending full snapshots"
	for jail in $pools; do zfs send $ZROOT/$jail/home@newsync | ssh -q ${bro} 'zfs receive -vFd zdata' ;done
	echo "renaming them to use them as a base for diff snapshots"
	for jail in $pools; do zfs rename $ZROOT/$jail/home@newsync $ZROOT/$jail/home@prevsync ;done
	ssh -q ${bro} 'for jail in ftp mail web; do zfs rename zdata/servers/$jail/home@newsync zdata/servers/$jail/home@prevsync ;done'
echo "`date`: ZFSync INIT ending."
	exit $?
fi
fi

echo "`date`: ZFSync starting."
for pool in $pools
do
	dataset="$ZROOT/${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 zdata" || 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 "`date`: ZFSync ending."

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

rm -f $LOCKFILE