Having a Rasbperry Pi Cluster allows you to learn, test and experiment concepts about distributed computing. The first challenge is always how to keep the pi’s up to date. Having four nodes seems still manageable, but what about 64 nodes? Although it is a little bit repetitive, to enter the exact same commands over and over again. Another friend would see just write a bash script that executes the exact command on each node via SSH. Hmm, wait, there is Ansible that does exactly that for you. So a quick jump into Ansible under Ubuntu.