How can write regex validate for zipcode in laravel validation?

I have a registration form. I need to validate zipcode. Validation rules must be integer, Max length not greater than 7.

I had tried validation but it validate zip must be 5. But some countries has 6 or 4 zipcode. Any help would be appreciated.

'zipcode'   => 'required|regex:/^[0-9]{5}(\-[0-9]{4})?$/',

via Chebli Mohamed