rendering env-var inside kubernetes kubeconfig yaml file

Question

I need to use an environment variable inside my kubeconfig file to point the NODE_IP of the Kubernetes API server.

My config is:

apiVersion: v1
clusters:
- cluster:
    insecure-skip-tls-verify: true
    server: https://$NODE_IP:6443
  name: docker-for-desktop-cluster
contexts:
- context:
    cluster: docker-for-desktop-cluster
    user: docker-for-desktop
  name: docker-for-desktop
current-context: docker-for-desktop
kind: Config
preferences: {}
users:
- name: docker-for-desktop
  user:
......

But it seems like the kubeconfig file is not getting rendered variables when I run the command:

kubectl --kubeconfig mykubeConfigFile get pods.

It complains as below:

Unable to connect to the server: dial tcp: lookup $NODE_IP: no such host

Did anyone try to do something like this or is it possible to make it work?

Thanks in advance

You can do `kubectl --kubeconfig mykubeConfigFile --server "https://${NODE_IP}:6443" get pods`. Read more about kubeconfig [here](https://kubernetes.io/docs/concepts/configuration/organize-cluster-access-kubeconfig/) — Amit Kumar Gupta, Sep 10 '19 at 18:33
@Amit thanks a lot for the response and editing my post, but I think helm is not supporting the --server option. I share my output of helm command below. Error: unknown flag: --server But anyway I dont know how happened but my problem is solved. I am able to upload helmchart within the pod with deafult kubeconfig configuration. So I didnt have to pass the new kubeconfig file anyway. — oguz, Sep 12 '19 at 11:17

Yasen · Accepted Answer · 2019-09-12T11:45:14.073

3

This thread contains explanations and answers:

... either wait Implement templates · Issue #23896 · kubernetes/kubernetes for the implementation of the templating proposal in k8s (not merged yet)

... or preprocess your yaml with tools like:

envsubst:

export NODE_IP="127.0.11.1"
envsubst < mykubeConfigFile.yml | kubectl --kubeconfig mykubeConfigFile.yml get pods

sed:

cat mykubeConfigFile.yml | sed s/\$\$EXTERNAL_IP/127.0.11.1/ | kubectl --kubeconfig mykubeConfigFile.yml get pods

edited Sep 12 '19 at 11:45

answered Sep 10 '19 at 16:33

Yasen

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thx for the suggestion. As I described I didnt have to pass kubeconfig file to the command finally. I have no idea why. But if i needed again envsubst is a solid solution i missed it. – oguz Sep 12 '19 at 11:22

rendering env-var inside kubernetes kubeconfig yaml file

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