No environment variable displayed through kubectl

user_3755528 0
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To display some environment variables in a pod on Kubernetes, I tried it in two ways.

(1) Connecting inside a pod

I connected to shell in a pod and I executed 'echo' command like below..

kubectl exec -it <pod-name> /bin/bash

then...

echo $KUBERNETES_SERVICE_HOST

I saw correct result as I expected.

(2) Send a command to a pod

kubectl exec <pod-name> -- echo $KUBERNETES_SERVICE_HOST

In this case, there is no output.

you can see the screenshot what I did. enter image description here

What is the problem here? What is difference between two situations?

Thanks you :)

kubernetes sh environment-variables linux bash
1 Answers

In the second case, '$' DOllar in the command references to your local host envrionment variables. And there is no such variable KUBERNETES_SERVICE_HOST on local host, the command that goes looks like below

kubectl exec -- echo

use below instead

kubectl exec c-hub-admin-app-systest-6dc46bb776-tvb99 -- printenv | grep KUBERNETES_SERVICE_HOST

enter image description here

user_73651100
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