This code is used on a Raspberry-Pi based Akka Cluster to demonstrate cluster formation, split-brain occurrence and Split Brain Resolver in a visual manner.

Each node is equipped with an 8-LED RGB strip where different LED's are used to show each node's state (Joining, Up, Weakly-up, Unreachable, Leaving, Exiting and Down/Removed). In addition, it shows if a node has a so-called leader role and whether a node is running an Akka Cluster Singleton (if one is created on the cluster).

In the last series of exercises, we deploy an actor based application (a Sudoku Solver) on the cluster and add monitoring (Cinnamon/Prometheus/Grafana) and tracing to the set-up (Open-tracing/Zipkin).

• Make sure you completed the installation of
  • Java 8 SDK
  • Some terminal (iTerm-2 on Mac, Terminator on Linux style OS-es, Powershell or ConEmu on Windows
  • curl
• Clone the project on your laptop

If you want to build your own physical cluster, you may want to have a look at the BOM here.

The recommended way to flash a customised OS image is documented in the next paragraph.

Instructions on where to get a fully configured OS can be found here.

The easiest and fastest way to flash a Hypriot OS instance that is ready to use for the Akka Cluster software can be found here.

In some cases it can be handy to use a so-called travel router which allows you to connect to a Wifi network on location, and still get access to a physical network with a fixed IP network address. This is because, currently, all nodes have statically configured IP addresses.

Details on how to configure such a (TP-Link TL-WR802N) router can be found here.