9953: If config cannot be read/parsed, show just the error without the stack trace.

diff --git a/services/dockercleaner/arvados_docker/cleaner.py b/services/dockercleaner/arvados_docker/cleaner.py
index 9dd7b12a08b7b45b50b018aa1a8c59a6aa8beed6..8b8c772e542adfb6decaa7be501dcafab8db91a5 100755 (executable)
--- a/services/dockercleaner/arvados_docker/cleaner.py
+++ b/services/dockercleaner/arvados_docker/cleaner.py
@@ -257,8 +257,12 @@ def load_config(arguments):
     args = parse_arguments(arguments)
 
     config = default_config()
-    with open(args.config, 'r') as f:
-        config.update(json.load(f))
+    try:
+        with open(args.config, 'r') as f:
+            c = json.load(f)
+            config.update(c)
+    except (FileNotFoundError, IOError, ValueError) as error:
+        sys.exit('error reading config file {}: {}'.format(args.config, error))
 
     configargs = vars(args).copy()
     configargs.pop('config')