External credential provider for authentication

[weibeld]

Does this client support external credential providers as described here? This feature was introduced in Kubernetes v1.10 and implemented in the Go client, and the Python client seems to implement it now too.

The feature allows the client to execute an external command to get a credential token that is then used for authenticating to the API server.

The thing is that this is required for Amazon EKS clusters. The external command here is aws-iam-authenticator. The authentication has to be configured in the kubeconfig file as follows:

users:
- name: ...test-cluster
  user:
    exec:
      apiVersion: client.authentication.k8s.io/v1alpha1
      command: aws-iam-authenticator
      args:
        - token
        - -i
        - test-cluster

It seems that if this feature is not implemented, then this client cannot be used for Amazon EKS clusters.

[brendandburns]

@weibeld it does not currently support 'exec' style authenticators. I'd welcome a PR if you want to add it.

You can see the authenticator specialization here:

https://github.com/kubernetes-client/javascript/blob/master/src/config.ts#L305

It probably needs some re-factoring to support multiple different providers anyway...

[brendandburns]

Just noticed, this is a duplicate of #34, closing in favor of that issue