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Cluster Administration

How to Merge Kubeconfig Files

Let's say you have a configuration file from kubeadm or another Kubernetes cluster, and you already have an existing kubeconfig file on your local system configured with other clusters.

Now, you want to merge the new configuration into the existing kubeconfig while preserving the configurations of other clusters.

Solution: You can merge a new kubeconfig file into your existing ~/.kube/config file using the KUBECONFIG environment variable and kubectl config view.

Follow the steps given below to merge and validate the Kubeconfig.

Step 1: Set the KUBECONFIG Environment Variable

Run the following command to temporarily merge both kubeconfig files

export KUBECONFIG=~/.kube/config:/path/to/new/kubeconfig

For example,

export KUBECONFIG=~/.kube/config:/Users/jacbo/Documents/GitHub/kubeadm-scripts/config

Step 2: Merge and Save the Configurations

Run this command to combine them into one

kubectl config view --flatten > ~/.kube/config-merged

Step 3: Replace the Original Config

Move the merged file back to ~/.kube/config

mv ~/.kube/config-merged ~/.kube/config

Step 4: Verify the Merged Config

Check if all contexts are available

kubectl config get-contexts

For example, in my case it lists many clusters.

$ kubectl config get-contexts
CURRENT   NAME                                                               CLUSTER                                                            AUTHINFO                                                           NAMESPACE
          do-blr1-jenkins-k8s-cluster                                        do-blr1-jenkins-k8s-cluster                                        do-blr1-jenkins-k8s-cluster-admin                                  
          kind-dev-cluster                                                   kind-dev-cluster                                                   kind-dev-cluster                                                   
*         kubernetes-admin@kubernetes                                        kubernetes                                                         kubernetes-admin

Step 5: Switch to required cluster context.

For example, for if you have merged kubeadm cluser config, you can set the context using:

kubectl config use-context kubernetes-admin@kubernetes

Step 6: Verify the config

Execute the following comands to verify the cluster connectivity using the following commands.

$ kubectl cluster-info

Kubernetes control plane is running at https://54.202.189.85:6443
CoreDNS is running at https://54.202.189.85:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

List nodes.

$ k get nodes

NAME           STATUS   ROLES           AGE     VERSION
controlplane   Ready    control-plane   2d19h   v1.31.6
node01         Ready    <none>          2d19h   v1.31.6
node02         Ready    <none>          2d19h   v1.31.6