I am trying to trace packets using sniffer using (https://github.com/eldadru/ksniff) but I am unable to make out how to trace packets and check if cluster IP is in use for Nodeport SVC.

I have the following scenario:

app1_sts.yaml
===

apiVersion: apps/v1
kind: StatefulSet
metadata:
  labels:
    cluster: appcluster
  name: app1
  namespace: app
spec:
  selector:
    matchLabels:
      cluster: appcluster
  serviceName: app1cluster
  template:
    metadata:
      labels:
        cluster: appcluster
    spec:
     containers:
       - name: app1-0
         image: localhost/linux:8
         imagePullPolicy: Always
         securityContext:
          privileged: false
         command: [/usr/sbin/init]
         ports:
         - containerPort: 8080
           name: appport
         readinessProbe:
            tcpSocket:
              port: 8080
            initialDelaySeconds: 120
            periodSeconds: 30
            failureThreshold: 20
         env:
         - name: container
           value: "true"
         - name: applist
           value: "app2-0"

app2_sts.yaml

apiVersion: apps/v1
kind: StatefulSet
metadata:
  labels:
    cluster: appcluster
  name: app2
  namespace: app
spec:
  selector:
    matchLabels:
      cluster: appcluster
  serviceName: app2cluster
  template:
    metadata:
      labels:
        cluster: appcluster
    spec:
     containers:
       - name: app2-0
         image: localhost/linux:8
         imagePullPolicy: Always
         securityContext:
          privileged: false
         command: [/usr/sbin/init]
         ports:
         - containerPort: 8080
           name: appport
         readinessProbe:
            tcpSocket:
              port: 8080
            initialDelaySeconds: 120
            periodSeconds: 30
            failureThreshold: 20
         env:
         - name: container
           value: "true"
         - name: applist
           value: "app1-0"

Services:

app-svc.yaml

apiVersion: v1
kind: Service
metadata:
  labels:
   cluster: appcluster
  name: appsvc
  namespace: rac
spec:
  clusterIP: None
  selector:
   cluster: appcluster
  type: ClusterIP

app_nodeport.svc.yaml

apiVersion: v1
kind: Service
metadata:
  name: app-svc-1
  namespace: app
spec:
  type: NodePort
  ports:
    - port: 8080
      nodePort: 33000
      targetPort: 8080
  selector:
    cluster: appcluster

Check the EP and Service:

[root@oper01 yaml_files]# kubectl get svc -n rac
NAME                TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)                          AGE
app-svc-1           NodePort    10.97.133.80     <none>        8080:31000/TCP                   46s
appsvc              ClusterIP   None             <none>        <none>                           66s

[root@oper01 yaml_files]# kubectl get ep -n rac
NAME                ENDPOINTS                            AGE
app-svc-1           10.244.1.19:8080,10.244.2.10:8080    81s
appsvc              10.244.1.19,10.244.2.10              101s

As per the following link:

https://kubernetes.io/docs/concepts/services-networking/service/

NodePort: Exposes the Service on each Node's IP at a static port (the NodePort). To make the node port available, Kubernetes sets up a cluster IP address, the same as if you had requested a Service of type: ClusterIP.

It states that cluster Ip is being used for nodeport but when I am using sniffer I do not see any packet coming to the pod from the cluster IP.