Decentralize cloudformation naming responsibilities (#3201)

* #3127 - Decentralize CF naming responsibilities

* Decentralize CloudFormation naming responsibilities

* Update URLs in cloudformation_resource_type functions

* Fix flake8 errors

* Black formatting

* Add a bunch of imports to populate CloudFormationModel.__subclasses__

* Add noqa to s3 models import statement in cloudformation/parsing.py

* Black formatting

* Remove debugging print statement

Co-authored-by: Bert Blommers <info@bertblommers.nl>

moto/core/__init__.py

@@ -1,6 +1,7 @@
 from __future__ import unicode_literals
 
 from .models import BaseModel, BaseBackend, moto_api_backend, ACCOUNT_ID  # noqa
+from .models import CloudFormationModel  # noqa
 from .responses import ActionAuthenticatorMixin
 
 moto_api_backends = {"global": moto_api_backend}

moto/core/models.py

@@ -8,6 +8,7 @@ import os
 import re
 import six
 import types
+from abc import abstractmethod
 from io import BytesIO
 from collections import defaultdict
 from botocore.config import Config
@@ -534,6 +535,47 @@ class BaseModel(object):
         return instance
 
 
+# Parent class for every Model that can be instantiated by CloudFormation
+# On subclasses, implement the two methods as @staticmethod to ensure correct behaviour of the CF parser
+class CloudFormationModel(BaseModel):
+    @abstractmethod
+    def cloudformation_name_type(self):
+        # This must be implemented as a staticmethod with no parameters
+        # Return None for resources that do not have a name property
+        pass
+
+    @abstractmethod
+    def cloudformation_type(self):
+        # This must be implemented as a staticmethod with no parameters
+        # See for example https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-dynamodb-table.html
+        return "AWS::SERVICE::RESOURCE"
+
+    @abstractmethod
+    def create_from_cloudformation_json(self):
+        # This must be implemented as a classmethod with parameters:
+        # cls, resource_name, cloudformation_json, region_name
+        # Extract the resource parameters from the cloudformation json
+        # and return an instance of the resource class
+        pass
+
+    @abstractmethod
+    def update_from_cloudformation_json(self):
+        # This must be implemented as a classmethod with parameters:
+        # cls, original_resource, new_resource_name, cloudformation_json, region_name
+        # Extract the resource parameters from the cloudformation json,
+        # delete the old resource and return the new one. Optionally inspect
+        # the change in parameters and no-op when nothing has changed.
+        pass
+
+    @abstractmethod
+    def delete_from_cloudformation_json(self):
+        # This must be implemented as a classmethod with parameters:
+        # cls, resource_name, cloudformation_json, region_name
+        # Extract the resource parameters from the cloudformation json
+        # and delete the resource. Do not include a return statement.
+        pass
+
+
 class BaseBackend(object):
     def _reset_model_refs(self):
         # Remove all references to the models stored