def _initialize_aws_identity_document(cls):
        """This method, tries to establish an HTTP connection to AWS instance
        identity document url. If the application is running on an EC2
        instance, we should be able to get back a valid JSON document. Make a
        http get request call and store data in local map.
        This method should only be called once.
        """

        if cls.inited:
            return

        content = get_request(_AWS_INSTANCE_IDENTITY_DOCUMENT_URI)
        if content is not None:
            content = json.loads(content)
            for env_var, attribute_key in _AWS_ATTRIBUTES.items():
                attribute_value = content.get(env_var)
                if attribute_value is not None:
                    aws_metadata_map[attribute_key] = attribute_value

            cls.is_running = True

        cls.inited = True
This method, tries to establish an HTTP connection to AWS instance
        identity document url. If the application is running on an EC2
        instance, we should be able to get back a valid JSON document. Make a
        http get request call and store data in local map.
        This method should only be called once.