Tcp traffic shifting task bug

Hi Everyone!
while doing tcp-traffic shifting task https://istio.io/docs/tasks/traffic-management/tcp-traffic-shifting/ i don’t get the expected output:
After third step when i run

export INGRESS_PORT=$(kubectl -n istio-system get service istio-ingressgateway -o jsonpath=’{.spec.ports[?(@.name==“tcp”)].port}’)

it give me 31400

but when i run

for i in {1…10}; do
docker run -e INGRESS_HOST=$INGRESS_HOST -e INGRESS_PORT=$INGRESS_PORT -it --rm busybox sh -c “(date; sleep 1) | nc $INGRESS_HOST $INGRESS_PORT”;
done

it shows

Unable to find image ‘busybox:latest’ locally
latest: Pulling from library/busybox
d9cbbca60e5f: Pull complete
Digest: sha256:836945da1f3afe2cfff376d379852bbb82e0237cb2925d53a13f53d6e8a8c48c
Status: Downloaded newer image for busybox:latest

after that it is terminated when i run again it show nothing.

expected output:

one Mon Nov 12 23:24:57 UTC 2018
one Mon Nov 12 23:25:00 UTC 2018
one Mon Nov 12 23:25:02 UTC 2018
one Mon Nov 12 23:25:05 UTC 2018
one Mon Nov 12 23:25:07 UTC 2018
one Mon Nov 12 23:25:10 UTC 2018
one Mon Nov 12 23:25:12 UTC 2018
one Mon Nov 12 23:25:15 UTC 2018
one Mon Nov 12 23:25:17 UTC 2018
one Mon Nov 12 23:25:19 UTC 2018

any help would be apprecated!