Laravel make dynamic root at runtime in filesystem

I am trying to upload image from one server to another server. I am using laravel filesystem. I have too many folders for file uploading. I want to make root location dynamic at runtime. But i am not getting any proper solution for this problem. Can anyone help me regarding this problem.

    [
        'driver' => '',
        'host' => '111.111.11.11',
        'username' => 'root',
        'password' => 'test!@##@!',
        'visibility' => 'public',
        'permPublic' => 0777,
        'root' => '/var/www/html/tests',
    ]