This code is used on a Raspberry-Pi based Akka Cluster to visually demonstrate cluster formation, split-brain occurrence and Split Brain Resolver.
Each node is equipped with an 10-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 addition to 10-LED Cluster there is also OLED display based cluster. Instructions for display assembly can be found here
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).
Removed the changelog & list of maintainers. Git history contains this information.
- Make sure you completed the installation of
- Java 11 SDK.
- Some terminal (iTerm-2 on Mac, Terminator on Linux style OS-es, Powershell or ConEmu on Windows).
- curl.
- Clone this project on your laptop.
Detailed instructions can be found here.
If you want to build your own physical cluster, you may want to have a look at the BOM 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.
Display version instructions are a little different and available 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.
- A bill of material can be found here
- A custom 10-LED strip that can be directly plugged on a Raspberry Pi board's GPIO connector can now be bought from Lunatech! You can buy them in a pack of 5. For more info, send a mail to info@lunatech.com.
- A schematic of the LED strip can be found here
Instructions for Display assembly are available here
Ubuntu has a 64-bit ARM version with built-in cloud-init support. As such, you can
flash 64-bit capable boards (Raspberry Pi 3 or 4) with this operating system. The
akka-pi-os-dhcp-64.yml cloud-init file has the required modifications to flash a
card for that version of the OS on ARM, with the most important difference with the
akka-pi-os-dhcp-32.yml being a 64-bit binary for the installation progress tracker.
This has been verified on a RPi4. A slightly modified version of the Hypriot flash utility is required though.
flash -n node-1 -u akka-pi-os-dhcp-64.yml \\n http://cdimage.ubuntu.com/releases/20.04/release/ubuntu-20.04.2-preinstalled-server-arm64+raspi.img.xz