bundles/backup-client: add check for last backup of specific client

bundles/backup-server/files/check_backup_for_node

@@ -0,0 +1,53 @@
+#!/usr/bin/env python3
+
+from datetime import datetime
+from json import load
+from subprocess import check_output
+from sys import argv, exit
+from time import time
+
+NODE = argv[1]
+
+NOW = int(time())
+DAY_SECONDS = 60 * 60 * 24
+
+snaps = set()
+
+try:
+    with open(f'/etc/backup-server/config.json', 'r') as f:
+        server_settings = load(f)
+
+    # get all existing snapshots for NODE
+    for line in check_output('LC_ALL=C zfs list -H -t snapshot -o name', shell=True).splitlines():
+        line = line.decode('UTF-8')
+
+        if line.startswith('{}/{}@'.format(server_settings['zfs-base'], NODE)):
+            _, snapname = line.split('@', 1)
+
+            if 'zfs-auto-snap' in snapname:
+                # migration from auto-snapshots, ignore
+                continue
+
+            ts, bucket = snapname.split('-', 1)
+            snaps.add(int(ts))
+
+    if not snaps:
+        print('No backups found!')
+        exit(2)
+
+    last_snap = sorted(snaps)[-1]
+    delta = NOW - last_snap
+
+    print('Last backup was on {}'.format(
+        datetime.fromtimestamp(last_snap).strftime('%Y-%m-%d %H:%M:%S'),
+    ))
+
+    if delta > (DAY_SECONDS * 2):
+        exit(2)
+    elif delta > DAY_SECONDS:
+        exit(1)
+    else:
+        exit(0)
+except Exception as e:
+    print(repr(e))
+    exit(3)