bundles/samba: add code to show up as time machine backup target

bundles/samba/metadata.py

@@ -24,3 +24,30 @@ def firewall(metadata):
             },
         },
     }
+
+
+@metadata_reactor.provides(
+    'zfs/datasets',
+)
+def timemachine_zfs(metadata):
+    shares = metadata.get('samba/timemachine-shares', set())
+
+    if not shares:
+        return {}
+
+    assert node.has_bundle('zfs'), f'{node.name}: time machine backups require zfs'
+
+    datasets = {
+        'tank/timemachine': {},
+    }
+
+    for share_name in shares:
+        datasets[f'tank/timemachine/{share_name}'] = {
+            'mountpoint': f'/srv/timemachine/{share_name}',
+        }
+
+    return {
+        'zfs': {
+            'datasets': datasets,
+        },
+    }