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

bundles/samba/items.py

@@ -11,9 +11,14 @@ svc_systemd = {
     },
 }
 
+timemachine_shares = node.metadata.get('samba/timemachine-shares', set())
+
 files = {
     '/etc/samba/smb.conf': {
         'content_type': 'mako',
+        'context': {
+            'timemachine': timemachine_shares,
+        },
         'triggers': {
             'svc_systemd:nmbd:restart',
             'svc_systemd:smbd:restart',
@@ -57,3 +62,24 @@ for user, uconfig in node.metadata.get('users', {}).items():
     last_action = {
         f'action:smbpasswd_for_user_{user}',
     }
+
+if timemachine_shares:
+    assert node.has_bundle('avahi-daemon'), f'{node.name}: samba needs avahi-daemon to publish time machine shares'
+
+    files['/etc/avahi/services/timemachine.service'] = {
+        'content_type': 'mako',
+        'context': {
+            'shares': timemachine_shares,
+        },
+    }
+
+    for share_name in timemachine_shares:
+        users[f'timemachine-{share_name}'] = {
+            'home': f'/srv/timemachine/{share_name}',
+        }
+
+        directories[f'/srv/timemachine/{share_name}'] = {
+            'owner': f'timemachine-{share_name}',
+            'group': f'timemachine-{share_name}',
+            'mode': '0700',
+        }