The Raspberry Pi Dramble is a cluster of Raspberry Pi computers that runs Drupal 8 on Kubernetes:
Jeff Geerling is the author of Ansible for DevOps and Ansible for Kubernetes, and hosts the Raspberry Pi Dramble website (which you're currently viewing) on his Dramble cluster, in the basement of his home in St. Louis, MO.
This website is a fun experiment to work within the limitations of (relatively) slow hardware, a (very) slow residential uplink, and other constraints, to build a robust and high-performance Drupal 8 website on top of Kubernetes. Or at least as robust and high-performance it can be ;)
Raspberries grow in bushes sometimes called 'brambles'. And traditionally, Raspberry Pi clusters have been called brambles. In this case, the bramble is running Drupal... thus it's a Dramble! But going even deeper still, fruits like raspberries, blackberries, and dewberries grow in what are called 'aggregates of drupelets'. So even more apropos!