KubeCon + CloudNativeCon Europe 2025

Providing Kubernetes as a service is difficult, since clusters have to be administered extrinsically (i.e., at infrastructure level), as well as intrinsically (i.e., at API level). While platform providers will often want to delegate the latter task to their customers, separating responsibilities is not always easy because infrastructure components are usually deployed as API resources themselves. Externalising the control plane partially solves this issue, yet components such as network, storage, and monitoring still run as pods in the cluster.

In this session, we present a novel approach to cluster infrastructure that we call “ephemeral nodes”. Utilizing two kubelets, our method achieves separate interfaces for platform providers and users. Along with a general discussion, we provide an implementation based on mutating webhooks and a CSI shim plugin. Along the way, we also show how the present method can be used for bare metal node pooling without the need for virtualisation.