In my headless service, I configure sessionAffinity so that connections from a particular client are passed to the same Pod each time as described here

Here is the manifest :

apiVersion: v1
kind: Service
metadata:
  name: service1
spec:
  clusterIP: None
  selector:
    app: nginx
  sessionAffinity: ClientIP
  sessionAffinityConfig:
    clientIP:
      timeoutSeconds: 30

I run some nginx pods to test :

$ kubectl create deployment nginx --image=stenote/nginx-hostname

The problem is that when I curl my service, I am redirected to different pods and sessionAffinity seems to be ignored.

$ kubectl run --generator=run-pod/v1 --rm utils -it --image arunvelsriram/utils bash
root@utils:/# for i in $(seq 1 10) ; do curl service1; done
nginx-78d58889-b7fm2
nginx-78d58889-b7fm2
nginx-78d58889-b7fm2
nginx-78d58889-b7fm2
nginx-78d58889-b7fm2
nginx-78d58889-8rpxd
nginx-78d58889-b7fm2
nginx-78d58889-62jlw
nginx-78d58889-8rpxd
nginx-78d58889-62jlw

NB. When I check with

$ kubectl describe  svc service1
Name:              service1
Namespace:         abdelghani
Labels:            <none>
Annotations:       <none>
Selector:          app=nginx
Type:              ClusterIP
IP Families:       <none>
IP:                None
IPs:               <none>
Session Affinity:  ClientIP
Events:            <none>

SessionAffinity configuration is present.

Note that my service is headless i.e. clusterIP: None. SessionAffinity seems to work fine with non-headless services. But, I cant find a clear explanation in the documentation. Is this related to the platform not doing any proxying?

Abdelghani