Raspberry PI Akka Cluster LED strips

Published on 2 May 2019 , last updated on 2 May 2019

Ever since Eric Loots from Lightbend first showed me the Raspberry-PI based Akka Cluster with special LED stripes, I’ve wanted (at least) one of them.

The Akka PI Cluster at Scala Days 2018

This is a 5 node cluster with special LED stripes setup in such a way that the LED colour and status (on, off, blinking, etc.) show in which state each node is. It is an excellent way to teach Akka Cluster, and since I do this regularly I was very interested from the beginning to get one of these myself.

Building a Raspberry PI cluster in itself is not that hard, you just plug things together. Except for the LED strips. There were no ready components that you could just plug onto the PIs so the strips had to be built by hand which includes a bit of soldering (Eric even made some very detailed instructions).

Since I wanted to build a few clusters for myself as well as possibly for students and clients, I thought that rather than spending a few hours soldering a few of those strips myself, it’d be easier and somehow less work to manufacture those strips as a ready-made module.

At Reactive Summit 2018 in Montréal, Eric and I discussed the project idea with Kathleen from Lightbend and got the green light to move forward, i.e. to design and manufacture these stripes for easy Akka Raspberry PI Cluster assembly.

I had already done a few projects involving PCB design in the past and contacted the folks at happylab.at with whom I had worked on one of these projects before. HappyLab is a fab lab in Vienna, Salzburg and Berlin that provides all kind of equipment and support to create things.

I’ll pass on the details of the PCB design work (many thanks to Christoph from HappyLab for all the help!), the initial test order as well as how getting customs clearance in Austria requires filling in a web form but then sending a fax to the authorities (try finding one of those in 2019). What matters is that on Tuesday the 500 strips arrived from the factory in Shenzhen.

Fresh from Shenzhen and through the customs
Carefully packaged strips


LED strip front and back

The bulk of the strips are now on the way to Eric in Belgium. Expect to hear more about this soon!

Test run of the LED strip on a raspberry PI

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