Kubewarden 1.4: WebAssembly Policy Engine Evolution

Introduction

Kubewarden 1.4, released on November 15, 2022, continues to advance WebAssembly-based Kubernetes policy enforcement. This release improves performance, expands language support, and delivers better Kubernetes integration for fast, secure policy evaluation.

Security features matter most when you’re trying to enforce guardrails without blocking delivery. This release is useful if you’re tightening policy, improving visibility, or hardening defaults across Kubernetes workloads.

WebAssembly Improvements

• Performance optimizations provide near-native performance for policy decisions with minimal latency overhead.
• Language flexibility enables writing policies in Rust, Go, AssemblyScript, and other languages that compile to WASM.
• Strong isolation ensures policies run in sandboxed environments, preventing policy code from affecting the host system.
• Portable policies work across different Kubernetes distributions and platforms without modification.

Policy Capabilities

1. Validation policies enforce security rules, resource constraints, and compliance requirements at admission time.
2. Mutation policies automatically modify resources to add defaults, labels, or inject configurations.
3. Context-aware policies leverage Kubernetes metadata and external data sources for intelligent decisions.
4. Policy composition enables combining multiple policies for complex enforcement scenarios.

Security & Performance

• Sandboxed execution ensures policy code cannot access host resources or compromise cluster security.
• Resource limits prevent policies from consuming excessive CPU or memory during evaluation.
• Fast startup enables rapid policy evaluation without the overhead of traditional policy engines.
• Low latency ensures admission decisions don’t significantly impact pod startup times.

Developer Experience

• Policy SDKs provide libraries for Rust, Go, and AssemblyScript to simplify policy development.
• Testing framework enables unit testing of policies before deployment.
• Policy registry provides a catalog of community-contributed policies for common use cases.
• Documentation includes comprehensive guides for writing, testing, and deploying policies.

Getting Started

kubectl apply -f https://raw.githubusercontent.com/kubewarden/policy-server/release-1.4/kubewarden-controller.yaml

Create a validation policy:

apiVersion: policies.kubewarden.io/v1
kind: ClusterAdmissionPolicy
metadata:
  name: require-labels
spec:
  policyServer: default
  module: registry://ghcr.io/kubewarden/policies/require-labels:v1.4.0
  rules:
  - apiGroups: [""]
    apiVersions: ["v1"]
    resources: ["pods"]
  mutating: false
  settings:
    required_labels:
      - app
      - version

Summary

Kubewarden 1.4 continues to evolve as a leading WebAssembly-based policy engine, combining performance with flexibility for Kubernetes policy enforcement.