bundles/zfs: introduce zfs-snapshot-backups, enable backups for nodes which need zfs-snapshot-backups

bundles/zfs/files/backup-pre-hook

@@ -0,0 +1,21 @@
+#!/bin/bash
+
+set -euo pipefail
+
+run-parts --exit-on-error -- /etc/zfs-snapshot-backup-pre.d
+
+
+% for dataset in sorted(node.metadata.get('zfs/filesystems_with_backup_snapshots')):
+if zfs get type ${dataset}@snapshot-backup >/dev/null 2>&1
+then
+    zfs destroy -f ${dataset}@snapshot-backup
+fi
+
+zfs snapshot ${dataset}@snapshot-backup
+
+mkdir -p /mnt/backup-snapshot${node.metadata['zfs']['datasets'][dataset]['mountpoint']}
+mount -t zfs ${dataset}@snapshot-backup /mnt/backup-snapshot${node.metadata['zfs']['datasets'][dataset]['mountpoint']}
+
+
+% endfor
+run-parts --exit-on-error -- /etc/zfs-snapshot-backup-post.d