#!/bin/sh

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

# 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'


bro="{{ bro }}"
pools="ftp mail web"

SENDZABBIX="zabbix_sender --config /usr/local/etc/zabbix6/zabbix_agentd.conf --key check.zfsync"
HOSTNAME=$(/bin/hostname -f | /usr/bin/cut -d '.' -f 1,1)
LOCKFILE=/tmp/zfsync.lock
ZROOT=zdata/servers

echo "$(date): ZFSync starting."
if [ -e "$LOCKFILE" ]
then
	echo "ERROR: $0 is already running with pid $(cat $LOCKFILE), check $LOCKFILE"
	exit 1
fi
echo ${$}>$LOCKFILE

alert()
{
	${SENDZABBIX} --value 1 >/dev/null
	exit $?
}

if [ "$1" ]
then
if [ "$1" = "init" ]
then
	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 -vFdu 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'
	exit $?
fi
fi

for pool in $pools
do
	dataset="$ZROOT/${pool}/home"
	echo "making new snapshot for ${pool}"
	zfs snapshot "${dataset}@newsync" || alert
	echo "sending snapshot"
	ssh -q "$bro" "zfs set readonly=on ${dataset}" || alert
	sleep 2
	zfs send -i @prevsync "${dataset}@newsync" | ssh -q "$bro" "zfs receive -vFdu zdata" || alert
	ssh -q "$bro" "zfs set readonly=off ${dataset}" || alert
	echo "cleaning"
	zfs destroy "${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
${SENDZABBIX} --value 0 >/dev/null

rm -f $LOCKFILE
echo "$(date): ZFSync ending."