get a resource manager or a given resource type.

        assumes the query is for the same underlying cloud provider.

def get_resource_manager(self, resource_type, data=None):
        """get a resource manager or a given resource type.

        assumes the query is for the same underlying cloud provider.
        """
        if '.' in resource_type:
            provider_name, resource_type = resource_type.split('.', 1)
        else:
            provider_name = self.ctx.policy.provider_name

        provider_resources = clouds[provider_name].resources
        klass = provider_resources.get(resource_type)
        if klass is None:
            raise ValueError(resource_type)

        # if we're already querying via config carry it forward
        if not data and self.source_type == 'config' and getattr(
                klass.get_model(), 'config_type', None):
            return klass(self.ctx, {'source': self.source_type})
        return klass(self.ctx, data or {})