core - allow providers to customize resource registry including basic filters/actions

c7n/filters/core.py

@@ -430,6 +430,7 @@ class ValueFilter(BaseValueFilter):
     schema_alias = True
     annotate = True
     required_keys = {'value', 'key'}
+    value_resolver_class = ValuesFrom
 
     def _validate_resource_count(self):
         """ Specific validation for `resource_count` type
@@ -544,7 +545,8 @@ def match(self, i):
             self.k = self.data.get('key')
             self.op = self.data.get('op')
             if 'value_from' in self.data:
-                values = ValuesFrom(self.data['value_from'], self.manager)
+                values = self.value_resolver_class(
+                    self.data['value_from'], self.manager)
                 self.v = values.get_values()
             else:
                 self.v = self.data.get('value')

c7n/provider.py

@@ -42,10 +42,17 @@ def initialize_policies(self, policy_collection, options):
         region execution and filtering policies for applicable regions.
         """
 
+
     @abc.abstractmethod
     def get_session_factory(self, options):
         """Get a credential/session factory for api usage."""
 
+    @staticmethod
+    def initialize_resource(resource_class):
+        """Perform initialize provider specific filter/action registry
+        registrations.
+        """
+
     @classmethod
     def get_resource_types(cls, resource_types):
         """Return the resource classes for the given type names"""

c7n/resources/aws.py

@@ -511,6 +511,17 @@ def upload_file(self, path, key):
                 'ServerSideEncryption': 'AES256'})
 
 
+class AwsValuesFrom(ValueFrom):
+    """Support provider specific data sources.
+    """
+
+
+class AwsValueFilter(Value):
+
+    value_resolver_class = AwsValuesFrom
+
+
+
 @clouds.register('aws')
 class AWS(Provider):
 
@@ -538,6 +549,11 @@ def get_session_factory(self, options):
             options.assume_role,
             options.external_id)
 
+    @staticmethod
+    def initialize_resource(resource_class):
+        """static method to initialize provider specific filter/actions"""
+        resource_class.filter_registry.register('value', AwsValueFilter)
+
     def initialize_policies(self, policy_collection, options):
         """Return a set of policies targetted to the given regions.