This is a helper function which will allow you to get the domain name in Wordpress both when in WEB and CLI mode:

function getDomain() {

    if(isset($_SERVER['HTTP_HOST'])){

        return $_SERVER['HTTP_HOST'];

    }

    if(function_exists('get_site_url')){

        $url = get_site_url();

        return parse_url($url,PHP_URL_HOST);

    }

    if(defined('BASE_PATH')){

        return basename(BASE_PATH);

    }

    return dirname(DIR);

}