I’m confused about the overlapping features between an API Gateway and a Service Mesh. We currently use Kong for our external traffic, but as our internal service-to-service communication grows, I'm hearing we need Istio or Linkerd. Do these tools replace the gateway, or do they work together? I'm worried about the operational overhead of managing a mesh.
3 answers
They actually solve different problems. Think of the API Gateway as your "North-South" gatekeeper—handling external requests, authentication, and rate limiting. The Service Mesh handles "East-West" traffic, which is the internal chatter between your services. In 2024, security standards like mTLS (mutual TLS) are becoming non-negotiable for internal traffic, and a mesh automates that without you having to write security logic in every single service. If you have more than 10-15 services, the overhead of the mesh is worth the observability and security benefits it provides.
Does the sidecar proxy in a service mesh like Istio add a significant amount of resource consumption to the Kubernetes nodes? We are already running pretty tight on our cloud budget and I don't want to double our bill.
The API Gateway is for the clients; the Service Mesh is for the developers. You likely need both if you're serious about zero-trust architecture and deep observability in production.
I agree with Amanda. Trying to make an API Gateway handle internal retries and circuit breaking for every service-to-service hop becomes an absolute nightmare to configure and maintain over time.
Brian, the sidecar (Envoy) does use some CPU and RAM, but it's usually around 10-15%. If cost is a major factor, look into "sidecar-less" meshes like Cilium or the newer Istio Ambient Mesh. They move the logic to the kernel level or a shared node agent, which drastically reduces the per-pod resource footprint.