updater: add --signal-no-updates flag

vmupdate/tests/test_vmupdate.py

@@ -33,9 +33,11 @@
 @patch('logging.FileHandler')
 @patch('logging.getLogger')
 def test_no_options_do_nothing(_logger, _log_file, _chmod, _chown, test_qapp):
-    args = []
     test_qapp.domains = test_qapp.Domains()
     TestVM("dom0", test_qapp, klass="AdminVM")
+    args = []
+    assert main(args, test_qapp) == 0
+    args = ['--signal-no-updates']
     assert main(args, test_qapp) == 100
 
 

vmupdate/vmupdate.py

@@ -55,7 +55,7 @@ def main(args=None, app=qubesadmin.Qubes()):
     if not targets:
         if not args.quiet:
             print("No qube selected for update")
-        return 100
+        return 100 if args.signal_no_updates else 0
 
     independent = [target for target in targets if target.klass in (
         'TemplateVM', 'StandaloneVM')]
@@ -75,7 +75,7 @@ def main(args=None, app=qubesadmin.Qubes()):
         args, independent, templ_statuses, app_statuses, log)
 
     ret_code = max(ret_code_independent, ret_code_appvm, ret_code_restart)
-    if ret_code == 0 and no_updates:
+    if ret_code == 0 and no_updates and args.signal_no_updates:
         return 100
     return ret_code
 
@@ -97,6 +97,10 @@ def parse_args(args, app):
                         help='Do not remove updater files from target qube')
     parser.add_argument('--dry-run', action='store_true',
                         help='Just print what happens.')
+    parser.add_argument(
+        '--signal-no-updates', action='store_true',
+        help='Return exit code 100 instread of 0 '
+             'if there is no updates available.')
 
     restart = parser.add_mutually_exclusive_group()
     restart.add_argument(