Networking Multiple Kind Kubernetes Clusters Together Using Native Routing
If you've ever needed to test multi-cluster Kubernetes features locally -- things like service mesh federation, cross-cluster service discovery, or multi-cluster networking -- you've probably hit the same wall I did: pods in one Kind cluster can't talk to pods in another. Their IPs are trapped inside their respective Docker containers with no route between them.
This post covers how to solve that by creating a flat network where any pod in any cluster can reach any other pod by IP.
When would you need this?
You'd reach for this setup when:
- Testing multi-cluster service meshes (Istio, Linkerd, Cilium) locally before deploying to real infrastructure
- Developing cross-cluster controllers that need direct pod-to-pod communication
- Reproducing multi-cluster networking bugs in a lightweight local environment
- Validating flat-network assumptions before committing to a CNI or network topology in production
If your use case also needs cross-cluster DNS resolution (pods addressing services by name across clusters), skip ahead to the Cilium recommendation below. If you just need IP-level reachability, the native routing approach will get you there with zero extra dependencies.