NOD8CX: I will not have a full D8 release on the day that Drupal 8 is released unless someone else volunteers to co-maintain that branch. This is not meant as criticism of the enormous effort others have but into D8, but an attempt to honestly inform anyone using this module of my plans.
Use Drupal's cron to call CiviCRM's cron. CiviCRM's cron can (and should) be called directly from the command line, but this is a simple way to define the user, pass, and sitekey used in the CiviCRM url and call CiviCRM's cron when it's not possible or convenient to configure CiviCRM's cron.
Hosting CiviCRM Cron