Using below command to deploy spark app (default from spark operator).

kubectl apply -f spark/template/spark-application.yaml

used this to create spark-application

Added below values along with memory and core to run as user 1000 but sill driver and executor runs in root user.added security context from here

spec:
  driver:
    securityContext:
      runAsUser: 1000    
  executor:
    securityContext:
      runAsUser: 1000

web-hook service is running in spark-operator namespace.

kubectl get service -n spark-operator    
NAME                                    TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)             AGE
spark-driver-metrics                    ClusterIP   172.20.134.198   <none>        8090/TCP            5h50m
spark-executor-metrics                  ClusterIP   172.20.91.165    <none>        8090/TCP            5h50m
spark-stream-1579262191507-driver-svc   ClusterIP   None             <none>        7078/TCP,7079/TCP   20m
spark-stream-ui-svc                     NodePort    172.20.57.54     <none>        4040:31337/TCP      20m
spark-webhook                           ClusterIP   172.20.123.24    <none>        443/TCP             5h50m

secrets details:

    kubectl get secrets -n spark-operator
    NAME                            TYPE                                  DATA   AGE
    default-token-2fgv7             kubernetes.io/service-account-token   3      6h13m
    spark-token-74b8n               kubernetes.io/service-account-token   3      6h13m
    spark-webhook-certs             Opaque     

                           4      6h11m

any help appreciated.