I realized I haven’t posted about my DrupalCon Seattle 2019 session titledEverything I know about Kubernetes I learned from a cluster of Raspberry Pis, so I thought I’d remedy that. First, here’s a video of the recorded session:
The original Pi Dramble 6-node cluster, running the LAMP stack.
I started running theRaspberry Pi Dramblein 2014, after I realized I could automate the setup of everything in a LAMP stack on a set of Raspberry Pi 2s using Ansible (one Pi for an HTTP load balancer / reverse proxy, two for PHP app backends, and two for MySQL redundancy. Kubernetes was the logical next step, so I moved things towards Kubernetes in 2017, but running Kubernetes was a lesson in pain due to the Pi’s limited memory (1 GB maximum) at the time.
When the Raspberry Pi 4 came around, I acquired some 2 GB models as quickly as I could, and redeployed onto them. Gone were the restrictions that were causing Kubernetes’ API to be flaky with the older Pis, and now the Pi 4 cluster is extremely reliable. Early on,cooling was an issue, but the recent firmware update has made that less problematic. I now power the cluster using the official PoE HAT, which means I only have one plug for each Pi, and everything fits nicely into a small travel case (if I want to bring the cluster with me anywhere).
The current Pi Dramble, running Kubernetes and sportingBlinkStick Nanos.
I even got it all to run off a 10, 000 mAh battery pack with a bunch of USB splitters … but it did not stay powered long, and kept giving low power warnings — so I’ll have to consider other options for a highly -mobile four-node Kubernetes bare-metal cluster.
I’ve continually updated the cluster so it is tested in aDocker-based Kubernetes environment, aVagrant-based Kubernetes local development environment, and of course, the Pi environment. The latter environment causes much consternation, as many common container images are not maintained in an
linux / armformat, which is required when running on the 32 – bit ARM OS the Pi uses, Raspbian. But the Pi Dramble abides, and it quietly goes on, serving up traffic forhttps://www.pidramble.comthrough The Years.
The officialPi Dramble Wikihas all the instructions for building your own Pi Kubernetes cluster, with links to buy all the parts I have, along with every step to get it running using open source Ansible roles to install Kubernetes and Docker for ARM, then configure a new four-node cluster.
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