Inside container check mount points.
kubectl apply -f efs-writer.yaml kubectl apply -f efs-reader.yaml
kubectl exec -it efs-writer -- tail /shared/out.txt kubectl exec -it efs-reader -- tail /shared/out.txt
Reference url :
https://computingforgeeks.com/eks-persistent-storage-with-efs-aws-service/
https://docs.aws.amazon.com/eks/latest/userguide/sec-group-reqs.html