Running WASM on Thalassa Kubernetes Service with RuntimeClass

We’ve added WebAssembly (WASM) support to our Kubernetes service. A RuntimeClass for WASM is automatically provisioned on every cluster, so you can run WASM workloads alongside your containers without any extra setup. This post explains how it works and how to use it.

Why run WASM on Kubernetes?

WebAssembly gives you a portable, sandboxed execution environment. WASM modules are typically much smaller than container images, start very quickly, and run with strong isolation. That makes them a good fit for sidecars, serverless-style functions, and workloads where you want fast cold starts and a small footprint. Running them on Kubernetes means you can schedule and scale WASM the same way you do containers—with the same APIs, networking, and observability.

How it works: RuntimeClass

Kubernetes lets you choose different runtimes per pod via RuntimeClass. On Thalassa Cloud Kubernetes, we provision a WASM RuntimeClass for you—the runtime and handler are already configured on the cluster. You only need to set runtimeClassName on your pods to use the WASM runtime instead of the default container runtime.

Schedule a pod with the WASM runtime

Set runtimeClassName to the provisioned RuntimeClass name (e.g. wasm) on your pod:

apiVersion: v1
kind: Pod
metadata:
  name: wasm-demo
spec:
  runtimeClassName: wasm
  containers:
    - name: app
      image: registry.nl-01.thalassa.cloud/<your-namespace>/<your-wasm-image>:tag
      # ... other container spec

The container image holds the WASM module (or the runtime pulls it). The node’s WASM runtime executes the module when the pod runs. Resource limits, probes, and networking work as for normal containers.

Try it on Thalassa Cloud

WASM support is available on our managed Kubernetes clusters. The WASM RuntimeClass is automatically provisioned. Create or use an existing cluster and start scheduling pods with runtimeClassName: wasm.