Security Patching a Self-Managed Kubernetes Cluster — Five Layers, Zero Magic
Managed Kubernetes providers make security patching look simple. You enable auto-upgrade on GKE, you click "update node group" on EKS, and the CVE goes away. What actually happens is that the provider patches the OS image, replaces the node, validates the binary, and restores your workloads — all in the time it takes to refresh the AWS console.
On a self-managed cluster, none of that is automatic. You own the OS. You own the runtime. You own the base images. You own the Helm chart versions. And when a CVE drops, you own the decision about which layer it lives in and which mechanism will close it.
This post documents all five patching layers on minicloud — a 5-node k3s cluster on bare-metal ThinkPads — what's automated, what requires a PR, and where the gaps were and how they were closed.