async def create(cls, url, *, keyring_filename=None, keyring_data=None):
        """Create a new `BootSource`.

        :param url: The URL for the boot source.
        :param keyring_filename: The path to the keyring file on the server.
        :param keyring_data: The GPG keyring data, binary. as a file-like
            object. For example: an open file handle in binary mode, or an
            instance of `io.BytesIO`.
        """
        data = await cls._handler.create(
            url=url, keyring_filename=coalesce(keyring_filename, ""),
            keyring_data=coalesce(keyring_data, ""))
        return cls._object(data)