How to set a url in drupal database or settings.php? I had created a controller in  custom module using drupal 8. 

 public function subscribe(Request $request) {

        $url='https://username:password@someurl.com/v1/subscriptions';


}

I am using git for development. This url is actually for Razorpay subscriptions. These url might get changed according to the mode in razorpay. So the url subscriptions in razorpay for test mode and live mode is different. I have to change url every time in this custom module while managing git.  Can I define this"$url" somewhere in backend in db or settings.php?
In your settings file add

$settings['razorpayUrl'] = 'https://example.com';


Then in your module

use Drupal\Core\Site\Settings;
$url = Settings::get('razorpayUrl');