if err != nil {
		return nil, err
	}

	client, err := storage.NewClient(context.Background(),
		option.WithCredentialsJSON(credsJSON),
		option.WithScopes(storage.ScopeReadWrite),
		option.WithUserAgent(fmt.Sprintf("gcs-tier-%s", tier)+SlashSeparator+ReleaseTag),
	)
	if err != nil {
		return nil, err
	}
	return &warmBackendGCS{client, conf.Bucket, conf.Prefix, conf.StorageClass}, nil
}