def app_config(app_config):
    """Customize application configuration."""
    app_config[
        'FILES_REST_STORAGE_FACTORY'] = 'invenio_s3.s3fs_storage_factory'
    app_config['S3_ENDPOINT_URL'] = None
    app_config['S3_ACCESS_KEY_ID'] = 'test'
    app_config['S3_SECRECT_ACCESS_KEY'] = 'test'
    return app_config