It is sad to me you actually need linkers/istio for this. EndpointSlices support topology labels which the article states is in vanilla kubernetes. Which means you can create different services for example a zone. Like "myservice-eu-west1a".

The problem is that a pod has no easy way to know what topology it is in to make the choice to go to myservice-eu-west1a. The feature for getting topology labels through the downward api is not there! A pod has no idea where its scheduled!

The only way to find out is to ask the kubernetes api, but this requires rbac, a client, libraries etc.. unacceptable! Guess what linkerd does for you?

I am glad for the feature linkerd offers as it solves a problem and I can see the benefit of perhaps doing latency based routing as well on top of this.

It just ticks me off we need something complex to do something simple: keep workloads to their own zone depending on where they are.