Injecting theapps.kubernetes.io/pod-index label into pods in a stateful set was a tremendous improvement and made things like defining services that only send traffic to master databases instead of replicas possible (when the scheme of using ordinal 0 as the master is used). But you cannot do the opposite: because Service selectors do not support negation, you cannot define a Service selector that sends all read-only traffic to replicas (by negating a match against ordinal 0).
I think it would be super useful to have a apps.kubernetes.io/pod-index-non-zero label, which would make this pattern possible. Thoughts?