Changing APIServer endpoint

[jaskeerat789]

Description

I have a k8s cluster bootstrapped with kubeone. I used a loadbalancer for the control plane node and passed the endpoint of this LB to the kubeone config (the endpoint is replaced with a random url below)

apiEndpoint:
  host: 'subdomain1.domain.xyz'
  port: 6443

Now i decide to shift my lb to a new sub-domain and re run the kubeone apply command with updated apiEndpoint

apiEndpoint:
  host: 'subdomain2.domain.xyz'
  port: 6443

But the kubeone still tries to access the older endpoint and fails

INFO[16:16:30 IST] Building Kubernetes clientset...             
WARN[16:16:31 IST] Task failed, error was: unable to build dynamic client: Get "https://subdomain1.domain.xyz:6443/api?timeout=32s": ssh: rejected: connect failed (Name or service not known) 

[kron4eg]

@jaskeerat789 unfortunately changing apiEndpoint is not supported

[jaskeerat789]

@jaskeerat789 unfortunately changing apiEndpoint is not supported

Is there a workaround that may or may not involve kubeone?

Also what is recommended in such scenarios?

[jaskeerat789]

Me and my team managed to achieve this with a simple ansible playbook. I think this can be made part of kubeone. I am listing all the steps we do in order to achieve this.

On master node

• We start by stopping kubelet.
• Next we delete existing apiserver certs and key
  • /etc/kubernetes/pki/apiserver.crt
  • /etc/kubernetes/pki/apiserver.key
• Then we update the endpoint in the config file generated by kubeone, located at ~/kubeone/cfg. we use find and replace strategy in anisble-playbook.
• We generate new certs for the updated endpoint using the following command

kubeadm init phase certs apiserver --config <config file from previous step>

• Next we delete all existing .conf files found in /etc/kubernetes/ so that our kubecofig can be updated with the new apiserver endpoint.
• To generate new updated conf file, we run the following command

kubeadm init phase kubeconfig all --config <config file from 3rd step>

• Next we restart kubelet and upload these conf files to configmap using the following command

kubeadm init phase upload-config all --config <config file from 3rd step>

• At last we restart the kubelet and container runtime to make sure everyone is using the updated apiserver endpoint

On worker nodes

• We start with stopping the kubelet.
• Then we update the apiserver endpoint in /etc/kubernetes/kubelet.conf using find and replace strategy.
• At last we restart kubelet.