server

type FS interface {
	Exists(ctx context.Context, path string) error
	Put(ctx context.Context, path string, r io.ReadSeeker) error
	PresignedURLForGet(ctx context.Context, path string, dur time.Duration) (string, error)
	PresignedURLForPut(ctx context.Context, path string, dur time.Duration) (string, error)
	CanonicalURL(path string) string
}