Fixes #1260 - Add enforced versioning to configuration files.

nucypher/config/base.py

@@ -2,6 +2,10 @@ import json
 import os
 from abc import ABC, abstractmethod
 
+from constant_sorrow.constants import (
+    UNKNOWN_VERSION
+)
+
 from nucypher.config import constants
 
 
@@ -70,6 +74,8 @@ class BaseConfiguration(ABC):
     INDENTATION = 2
     DEFAULT_CONFIG_ROOT = constants.DEFAULT_CONFIG_ROOT
 
+    VERSION = NotImplemented
+
     class ConfigurationError(RuntimeError):
         pass
 
@@ -79,6 +85,9 @@ class BaseConfiguration(ABC):
     class NoConfigurationRoot(InvalidConfiguration):
         pass
 
+    class OldVersion(InvalidConfiguration):
+        pass
+
     def __init__(self,
                  config_root: str = None,
                  filepath: str = None,
@@ -220,11 +229,17 @@ class BaseConfiguration(ABC):
 
     def serialize(self, serializer=json.dumps) -> str:
         """Returns the JSON serialized output of `static_payload`"""
-        serialized_payload = serializer(self.static_payload(), indent=self.INDENTATION)
+        payload = self.static_payload()
+        payload['version'] = self.VERSION
+        serialized_payload = serializer(payload, indent=self.INDENTATION)
         return serialized_payload
 
     @classmethod
     def deserialize(cls, payload: str, deserializer=json.loads) -> dict:
         """Returns the JSON deserialized content of `payload`"""
         deserialized_payload = deserializer(payload)
+        version = deserialized_payload.pop('version', UNKNOWN_VERSION)
+        if version != cls.VERSION:
+            raise cls.OldVersion(f"Configuration file is the wrong version "
+                                 f"Expected version {cls.VERSION}; Got version {version}")
         return deserialized_payload

nucypher/config/node.py

@@ -45,6 +45,8 @@ class CharacterConfiguration(BaseConfiguration):
     'Sideways Engagement' of Character classes; a reflection of input parameters.
     """
 
+    VERSION = 1  # bump when static payload scheme changes
+
     CHARACTER_CLASS = NotImplemented
     DEFAULT_CONTROLLER_PORT = NotImplemented
     DEFAULT_DOMAIN = 'goerli'
@@ -284,7 +286,6 @@ class CharacterConfiguration(BaseConfiguration):
         """
         Warning: This method allows mutation and may result in an inconsistent configuration.
         """
-
         payload = cls._read_configuration_file(filepath=filepath)
         node_storage = cls.load_node_storage(storage_payload=payload['node_storage'],
                                              federated_only=payload['federated_only'])
@@ -310,8 +311,7 @@ class CharacterConfiguration(BaseConfiguration):
         try:
             node_configuration = cls(filepath=filepath, provider_process=provider_process, **assembled_params)
         except TypeError as e:
-            # TODO: Trigger configuration migration?
-            raise cls.ConfigurationError(f"Your configuration file may be out of date: {e}")
+            raise cls.ConfigurationError(e)
         return node_configuration
 
     def validate(self) -> bool: