I’m worried about "east-west" traffic security in our cluster. If one pod is compromised, an attacker can move laterally to any other service because everything is open by default. I've heard about Service Meshes like Istio and Linkerd, but they seem very heavy. What is the standard way to implement mTLS and network policies without killing the cluster performance?
3 answers
You should start with Kubernetes Network Policies before jumping into a full Service Mesh. Network Policies are like a firewall for your pods; you can explicitly define which pods are allowed to talk to each other based on labels. If you need encryption (mTLS) and observability, then look at a "Sidecar-less" service mesh like Cilium. It uses eBPF technology to handle security at the kernel level, which is much faster and less resource-intensive than the sidecar model used by Istio. This gives you high-level security without the massive CPU and RAM overhead of running a proxy in every single pod.
Is it difficult to migrate from standard K8s networking to a Service Mesh like Istio once the app is already live?
Always remember that security is layers. Network policies are your first line of defense, but regular container scanning is just as important.
True, Cynthia. No amount of mTLS will save you if the container image itself has a high-severity vulnerability that allows remote code execution!
It can be quite intrusive, Paul. Istio requires you to inject a "sidecar" proxy into every pod, which changes how traffic flows. You often have to update your service definitions and handle potential protocol conflicts (like with MySQL or certain gRPC setups). My advice is to implement it in "Permissive" mode first. This allows both encrypted and unencrypted traffic. Once you verify that everything is working through the proxy, you can flip the switch to "Strict" mTLS to enforce security across the whole cluster.