Don't crash when receiving unknown configuration variables

Instead of crashing if the monkey deserializes an unknown configuration
variable, send an error message to the current monkey server and keep on
working.

fixes guardicore#26

chaos_monkey/config.py

@@ -45,6 +45,11 @@ def _cast_by_example(value, example):
 
 class Configuration(object):
     def from_dict(self, data):
+        """
+        Get a dict of config variables, set known variables as attributes on self.
+        Return dict of unknown variables encountered.
+        """
+        unknown_variables = {}
         for key, value in data.items():
             if key.startswith('_'):
                 continue
@@ -55,9 +60,11 @@ def from_dict(self, data):
             try:
                 default_value = getattr(Configuration, key)
             except AttributeError:
-                raise
+                unknown_variables[key] = value
+                continue
 
             setattr(self, key, _cast_by_example(value, default_value))
+        return unknown_variables
 
     def as_dict(self):
         result = {}

chaos_monkey/control.py

@@ -124,14 +124,31 @@ def load_control_config():
             return
 
         try:
-            WormConfiguration.from_dict(reply.json().get('config'))
+            unknown_variables = WormConfiguration.from_dict(reply.json().get('config'))
             LOG.info("New configuration was loaded from server: %r" % (WormConfiguration.as_dict(),))
         except Exception, exc:
             # we don't continue with default conf here because it might be dangerous
             LOG.error("Error parsing JSON reply from control server %s (%s): %s",
                       WormConfiguration.current_server, reply._content, exc)
             raise Exception("Couldn't load from from server's configuration, aborting. %s" % exc)
 
+        if unknown_variables:
+            ControlClient.send_config_error()
+
+    @staticmethod
+    def send_config_error():
+        if not WormConfiguration.current_server:
+            return
+        try:
+            requests.patch("https://%s/api/monkey/%s" % (WormConfiguration.current_server, GUID),
+                                data=json.dumps({'config_error': True}),
+                                headers={'content-type': 'application/json'},
+                                verify=False,
+                                proxies=ControlClient.proxies)
+        except Exception, exc:
+            LOG.warn("Error connecting to control server %s: %s", WormConfiguration.current_server, exc)
+            return {}
+
     @staticmethod
     def check_for_stop():
         ControlClient.load_control_config()

chaos_monkey/requirements.txt

@@ -12,3 +12,5 @@ psutil
 PyInstaller
 ecdsa
 netifaces
+mock
+nose

monkey_island/cc/main.py

@@ -86,6 +86,8 @@ def patch(self, guid):
             update['$set']['config'] = monkey_json['config']
         if 'tunnel' in monkey_json:
             update['$set']['tunnel'] = monkey_json['tunnel']
+        if 'config_error' in monkey_json:
+            update['$set']['config_error'] = monkey_json['config_error']
 
         return mongo.db.monkey.update({"guid": guid}, update, upsert=False)