#!/bin/sh
# {{ ansible_managed }}

# Configure restic through environment variables.
export RESTIC_PASSWORD_FILE="/root/.restic.pass"
export RESTIC_REPOSITORY_FILE="/root/.restic.repo"
export GOMAXPROCS=3

indent() {
	sed 's/^/        /'
}

# Ask the kernel for a list of all ZFS filesystems.
FS_LIST="$(zfs list -H -t filesystem -o name)"

# Back up all mounted ZFS file systems with restic one at a time.
echo "Backing up ZFS filesystems:"
for FS in $FS_LIST
do
	echo # Seperate the file systems by empty lines (for human consumption)

	# Because scripts shouldn't meddle in the system configuration we
	# have to skip over unmounted file systems.
	MNT="$(zfs get -H -t filesystem -o value mountpoint "$FS")"
	case "$MNT" in
		/*)
			echo "* The file system \"$FS\" is mounted at \"$MNT\"."
			;;
		*)
			echo "* Skipping \"$FS\" (no valid mountpoint)."
			continue
			;;
	esac
	if [ "$(zfs get -H -o value mounted "$FS")" = "no" ]
	then
		echo "* Skipping \"$FS\" (not mounted)."
		continue
	fi

	# Clean up if the previous run failed
	if [ -e "$MNT/.zfs/snapshot/restic" ]
	then
		echo "* Deleting stale restic snapshot of \"$FS\"."
		zfs destroy -v "$FS@restic" 2>&1 | indent
	fi

	# It's important to backup from a snapshot to get a consistent backup.
	echo "* Taking ZFS snapshot of \"$FS\"."
	zfs snapshot "$FS@restic" 2>&1 | indent

	# Finally backup the filesystem to a (remote) restic repo.
	echo "* Backing up \"$FS\"."
	nice -n 15 restic backup "$MNT/.zfs/snapshot/restic" 2>&1 | indent

	# Clean up the ZFS snapshot.
	echo "* Deleting ZFS snapshot of \"$FS\"."
	zfs destroy -v "$FS@restic" 2>&1 | indent
done

echo
echo

# Ask the kernel for a list of all ZFS volumes.
VOL_LIST="$(zfs list -H -t volume -o name)"

echo "Backing up ZFS volumes:"
for VOL in $VOL_LIST
do
	echo

	if [ -e "/dev/zvol/$VOL@restic" ]
	then
		echo "* Deleting stale restic snapshot of \"$VOL\"."
		zfs destroy -v "$VOL@restic" 2>&1 | indent
	fi

	echo "* Taking ZFS snapshot of \"$VOL\"."
	zfs snapshot "$VOL@restic" 2>&1 | indent

	echo "* Backing up \"$VOL\"."
	buffer -s128k -m 128m -i "/dev/zvol/$VOL@restic" | nice -n 15 restic backup --stdin --stdin-filename "$VOL" 2>&1 | indent

	echo "$ Deleting ZFS snapshot of \"$VOL\"."
	zfs destroy -v "$VOL@restic" 2>&1 | indent
done


echo
echo
echo

# Delete old backups
echo "* Thin out older backups."
restic forget --keep-yearly 3 --keep-monthly 12 --keep-weekly 13 --keep-daily 31 2>&1 | indent

echo "* Prune unreferenced data from the repository."
restic prune 2>&1 | indent