Kubewarden 1.0: WebAssembly-Based Policy Engine

Introduction

Kubewarden 1.0 — WebAssembly-Based Policy Engine — was released on November 10, 2021.

Policy usually becomes urgent the first time you need to stop a risky manifest from shipping — or when you’re trying to make standards repeatable across teams.

In this release: Kubewarden 1.0 delivers a WebAssembly-based policy engine for Kubernetes, enabling fast, secure policy evaluation with language flexibility and low overhead.

WebAssembly-Based Policies

• Language flexibility enables writing policies in Rust, Go, AssemblyScript, and other languages that compile to WASM.
• Fast evaluation provides near-native performance for policy decisions with minimal latency overhead.
• 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.

Integration & Ecosystem

• Kubernetes admission webhooks provide seamless integration with Kubernetes admission control.
• Policy server architecture enables centralized policy management with horizontal scaling.
• Metrics & observability exposes detailed metrics for policy evaluation performance and outcomes.
• GitOps support enables policy management through Git repositories and CI/CD pipelines.

Comparison with Traditional Policy Engines

• Performance advantages from WASM’s near-native execution speed compared to interpreted policy languages.
• Language choice flexibility allows teams to use their preferred programming language for policies.
• Isolation benefits from WASM’s sandboxed execution model compared to traditional policy engines.
• Portability enables policies to run consistently across different environments and platforms.

Getting Started

kubectl apply -f https://raw.githubusercontent.com/kubewarden/policy-server/release-1.0/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:v1.0.0
  rules:
  - apiGroups: [""]
    apiVersions: ["v1"]
    resources: ["pods"]
  mutating: false
  settings:
    required_labels:
      - app
      - version

Summary

Kubewarden 1.0 introduces a new paradigm for Kubernetes policy enforcement, combining the performance of WebAssembly with the flexibility of multiple programming languages.