Technology · Ebook

Kubewarden: Policy as WebAssembly for Kubernetes

by Shriira Press

Every Kubernetes cluster needs a gatekeeper to decide which Pods, images, and configurations are allowed. Kubewarden answers that need with a striking idea: it runs admission policies as WebAssembly modules, so rules can be written in Rust, Go, CEL, or Rego and distributed like container images through OCI registries. This book begins with the admission-control machinery inside the API server, then walks through Kubewarden's architecture, the controller and the Rust Policy Server, and the sandbox that isolates each policy. It explores how Wasm policies are written and shipped with kwctl, how the ClusterAdmissionPolicy and PolicyServer resources fit together, how context-aware policies and policy groups express richer rules, and how the audit scanner, Sigstore verification, and monitor mode round out day-two operations.

Contents

1. 1Preface
2. 2Chapter 1 — A Universal Policy Engine
3. 3Chapter 2 — Admission Control in Kubernetes
4. 4Chapter 3 — The Kubewarden Architecture
5. 5Chapter 4 — Policies as WebAssembly
6. 6Chapter 5 — The Policy Custom Resources
7. 7Chapter 6 — Writing and Distributing Policies
8. 8Chapter 7 — Context-Aware Policies and Policy Groups
9. 9Chapter 8 — Auditing, Supply Chain, and Day-Two Operations
10. 10Chapter 9 — Kubewarden in Practice