The Operator Pattern in Nomad

The Operator Pattern from Kubernetes is an excellent way of handling tasks in a cluster in an automated way, for example, provisioning applications, running backups, requesting certificates, and injecting chaos testing. As a Nomad user, I wanted to do something similar for my clusters, so I set about seeing how it would be possible. It turns out; it is much easier than I expected! While Nomad doesn’t support the idea of Custom Resource Definitions, we can achieve an operator by utilising a regular Nomad job and the nomad HTTP API....

November 22, 2021 · 8 min

The Problem with CPUs and Kubernetes

Key Takeaway: os .cpus() returns the number of cores on a Kubernetes host, not the number of cores assigned to a pod. Investigating excessive memory usage Recently, when I was looking through a cluster health dashboard for a Kubernetes cluster, I noticed that one of the applications deployed was using a considerable amount of RAM - way more than I thought could be reasonable. Each instance (pod) of the application used approximately 8 GB of RAM, which was definitely excessive for a reasonably simple NodeJS webserver....

June 2, 2021 · 2 min

Nomad Good, Kubernetes Bad

I will update this post as I learn more (both positive and negative), and is here to be linked to when people ask me why I don’t like Kubernetes, and why I would pick Nomad in most situations if I chose to use an orchestrator at all. TLDR: I don’t like complexity, and Kubernetes has more complexity than benefits. Operational Complexity Operating Nomad is very straight forward. There are very few moving parts, so the number of things which can go wrong is significantly reduced....

November 21, 2019 · 6 min