K3s is a lightweight Kubernetes distribution that can be used to run Kubernetes clusters on a variety of devices, including embedded systems, edge devices, and personal computers. It is a popular choice for small and medium-sized businesses that are looking for a cost-effective and easy-to-use way to run Kubernetes.
However, k3s is plagued by a CPU usage bug that the project can’t seem to shake.
A year ago I wrote about a problem where an idle k3s cluster will gradually increase its cpu use over time. I was able to repeat this problem in both versions 1.21 and 1.22.
Now that it has been some time and a couple new versions have been released, I wanted to go back and test it out again.
I spun up a fresh Debian VM and installed k3s 1.25.7 and let it idle for a day.
I observed the exact same pattern. The idle CPU use of the k3s node started at about 8% and seemed to increase about 1% per day.
But the existence of this CPU-use bug negates the whole point of the lightweighted-ness of k3s. And this bug is truly unique to k3s. I have a VM running a k8s cluster as well on the same hypervisor and its CPU use stays consistent for weeks on end.
Its really disappointing this remains an issue.