muti domain support.

Hi,

In CI3 , it was:

    if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == "on") {
    $ssl_set = "s";
    } else {
    $ssl_set = "";
    }
    */

    //$config['base_url'] = 'http'.$ssl_set.'://'.$_SERVER['HTTP_HOST'];

in CI4, if statements do not seem to work and give a 500 error.
What is the best way to use/detect multiple subdomains/domain ?

    public $baseURL = ??


The SaaS application that I am trying to port from CI3 works like

subdomain1.domain.com
subdomain2.domain.com ..   -- can also be mapped to domain2.com 



I am checking how to achieve the same in CI4 ?


Thanks,