Prioritise remote user config over device

mycroft/configuration/config.py

@@ -20,11 +20,19 @@
 from os.path import exists, isfile
 from requests import RequestException
 
-from mycroft.util.json_helper import load_commented_json, merge_dict
+from mycroft.util.json_helper import (
+    delete_key_from_dict,
+    load_commented_json,
+    merge_dict
+)
 from mycroft.util.log import LOG
 
-from .locations import (DEFAULT_CONFIG, SYSTEM_CONFIG, USER_CONFIG,
-                        WEB_CONFIG_CACHE)
+from .locations import (
+    DEFAULT_CONFIG,
+    SYSTEM_CONFIG,
+    USER_CONFIG,
+    WEB_CONFIG_CACHE
+)
 
 
 def is_remote_list(values):
@@ -38,6 +46,20 @@ def is_remote_list(values):
     return True
 
 
+def prune_config(config, prune_list):
+    """Delete list of nested keys from the provided config.
+
+    Arguments:
+        config (dict): config to prune
+        prune_list (list(str)): list of keys to delete. Each item may be a
+                                period separated list of nested keys eg
+                                ["nested.dict.key", "listener.sample_rate"]
+    """
+    for key in prune_list:
+        config = delete_key_from_dict(key, config)
+    return config
+
+
 def translate_remote(config, setting):
     """Translate config names from server to equivalents for mycroft-core.
 
@@ -83,6 +105,7 @@ def translate_list(config, values):
 
 class LocalConf(dict):
     """Config dictionary from file."""
+
     def __init__(self, path):
         super(LocalConf, self).__init__()
         if path:
@@ -124,6 +147,7 @@ def merge(self, conf):
 
 class RemoteConf(LocalConf):
     """Config dictionary fetched from mycroft.ai."""
+
     def __init__(self, cache=None):
         super(RemoteConf, self).__init__(None)
 
@@ -203,20 +227,42 @@ def load_config_stack(configs=None, cache=False):
         Returns:
             (dict) merged dict of all configuration files
         """
+        # system administrators can define different constraints in how
+        # configurations are loaded
         if not configs:
-            configs = [LocalConf(DEFAULT_CONFIG), RemoteConf(),
-                       LocalConf(SYSTEM_CONFIG), LocalConf(USER_CONFIG),
+            configs = [LocalConf(DEFAULT_CONFIG), LocalConf(SYSTEM_CONFIG),
+                       RemoteConf(), LocalConf(USER_CONFIG),
                        Configuration.__patch]
         else:
             # Handle strings in stack
             for index, item in enumerate(configs):
                 if isinstance(item, str):
                     configs[index] = LocalConf(item)
 
+        # Build maintainers and system administrators may prevent users from
+        # modifying specific keys within the configuration.
+        system_config = LocalConf(SYSTEM_CONFIG) or {}
+        remote_config_disabled = system_config.get(
+            'disable_remote_config', False)
+        user_config_disabled = system_config.get(
+            'disable_user_config', False)
+        protected_keys = system_config.get('protected_keys', [])
+
         # Merge all configs into one
         base = {}
-        for c in configs:
-            merge_dict(base, c)
+        for config in configs:
+
+            # handle system constraints
+            if isinstance(config, RemoteConf):
+                if remote_config_disabled:
+                    continue
+                prune_config(config, protected_keys)
+            elif isinstance(config, LocalConf) and config.path == USER_CONFIG:
+                if user_config_disabled:
+                    continue
+                prune_config(config, protected_keys)
+
+            merge_dict(base, config)
 
         # copy into cache
         if cache:

mycroft/configuration/mycroft.conf

@@ -2,20 +2,31 @@
   // Definition and documentation of all variables used by mycroft-core.
   //
   // Settings seen here are considered DEFAULT.  Settings can also be
-  // overridden at the REMOTE level (set by the user via
-  // https://home.mycroft.ai), at the SYSTEM level (typically in the file
-  // '/etc/mycroft/mycroft.conf'), or at the USER level (typically in the
+  // overridden at the SYSTEM level (typically in the file
+  // '/etc/mycroft/mycroft.conf'), at the REMOTE level (set by the user via
+  // https://home.mycroft.ai), or at the USER level (typically in the
   // file '~/.mycroft/mycroft.conf').
   //
   // The load order of settings is:
   //   DEFAULT
-  //   REMOTE
   //   SYSTEM
+  //   REMOTE
   //   USER
   //
   // The Override: comments below indicates where these settings are generally
-  // set outside of this file.  The load order is always followed, so an
-  // individual systems can still apply changes at the SYSTEM or USER levels.
+  // set outside of this file.  The load order is always followed, so a
+  // specific system can set relevant attributes at the SYSTEM level, and users
+  // can further customize their experience at the REMOTE or USER levels.
+
+  // REMOTE or USER configurations can be disabled thereby requiring root
+  // access to the system to change any config parameters.
+  "disable_remote_config": false,
+  "disable_user_config": false,
+
+  // Alternatively a set of protected keys can be defined. This prevents
+  // either REMOTE or USER from modifying these settings. Nested keys should
+  // be provided as period separated strings eg ["listener.sample_rate"]
+  "protected_keys": [],
 
   // Language used for speech-to-text and text-to-speech.
   // Code is a BCP-47 identifier (https://tools.ietf.org/html/bcp47), lowercased

mycroft/util/json_helper.py

@@ -13,6 +13,7 @@
 # limitations under the License.
 #
 import json
+from copy import copy
 
 
 def merge_dict(base, delta):
@@ -32,6 +33,28 @@ def merge_dict(base, delta):
             base[k] = dv
 
 
+def delete_key_from_dict(key, dictionary):
+    """Recursivily find nested key in a dict and delete it.
+
+    Arguments:
+        key (str): a period separated list of nested keys to remove
+                   eg "nested.dict.keys"
+        dictionary (dict): the dictionary to remove keys from
+    Returns:
+        Dict: original dictionary with specified keys deleted.
+    """
+    modified_dict = copy(dictionary)
+    key_list = key.split('.')
+    if len(key_list) == 1 and modified_dict.get(key) is not None:
+        del modified_dict[key]
+    elif len(key_list) > 1:
+        remaining_keys = '.'.join(key_list[1:])
+        if modified_dict.get(key_list[0]) is not None:
+            modified_dict[key_list[0]] = delete_key_from_dict(
+                remaining_keys, modified_dict[key_list[0]])
+    return modified_dict
+
+
 def load_commented_json(filename):
     """ Loads an JSON file, ignoring comments
 

test/unittests/configuration/test_configuration.py

@@ -1,6 +1,8 @@
 from unittest.mock import MagicMock, patch
 from unittest import TestCase
 import mycroft.configuration
+from mycroft.configuration.locations import SYSTEM_CONFIG, USER_CONFIG
+from mycroft.util.json_helper import merge_dict
 
 
 class TestConfiguration(TestCase):
@@ -64,10 +66,18 @@ def test_local(self, mock_json_loader, mock_isfile, mock_exists,
         lc = mycroft.configuration.LocalConf('test')
         self.assertEqual(lc, {})
 
-    @patch('mycroft.configuration.config.RemoteConf')
-    @patch('mycroft.configuration.config.LocalConf')
+    def test_prune_config(self):
+        prune_config = mycroft.configuration.config.prune_config
+        config = {'a': 1, 'b': {'c': 1, 'd': 2}, 'e': 3}
+        self.assertEqual(prune_config(config, ['b']), {'a': 1, 'e': 3})
+        self.assertEqual(prune_config(config, ['b.c']), {
+                         'a': 1, 'b': {'d': 2}, 'e': 3})
+        self.assertEqual(prune_config(config, ['b', 'e']), {'a': 1})
+        self.assertEqual(prune_config(config, ['b', 'b.c']), {'a': 1, 'e': 3})
+
+    @patch('mycroft.configuration.config.RemoteConf.__new__')
+    @patch('mycroft.configuration.config.LocalConf.__new__')
     def test_update(self, mock_remote, mock_local):
-        mock_remote.return_value = {}
         mock_local.return_value = {'a': 1}
         c = mycroft.configuration.Configuration.get()
         self.assertEqual(c, {'a': 1})

test/unittests/util/test_json_helper.py

@@ -17,7 +17,18 @@
 
 from os.path import dirname, join
 
-from mycroft.util.json_helper import load_commented_json
+from mycroft.util.json_helper import delete_key_from_dict, load_commented_json
+
+
+class TestDictUtils(unittest.TestCase):
+
+    def test_delete_key_from_dict(self):
+        dct = {'a': 1, 'b': {'c': 1, 'd': 2}}
+        self.assertEqual(delete_key_from_dict("b", dct), {'a': 1})
+        self.assertEqual(delete_key_from_dict(
+            "b.c", dct), {'a': 1, 'b': {'d': 2}})
+        self.assertEqual(delete_key_from_dict(
+            "b.c", dct), {'a': 1, 'b': {'d': 2}})
 
 
 class TestFileLoad(unittest.TestCase):