Uchechukwu Onyekwuluje's Knowledge & Brain Dumps

Kubernetes Multi Cluster Management with kubectl

Installing a kubernetes cluster involves a lot of steps and can be very complex. When you have a running cluster, it’s easy to manage that cluster from the master node or a node with kubectl configured. This becomes cumbersome and difficult to manage as the cluster increases in size and also when there is a need to integrate kubernetes with CI/CD tools. This post is geared at simplifying the kubectl configuration for managing multiple clusters

Setup Requirements

This post assumes the following:

Config Components

Create the .kube forlder on the node with kubectl installed

mkdir /home/$USER/.kube

Copy the kubernetes admin config to the admin node.

export SERVER1="server-ip-address" #192.168.1.2
export SERVER2="server-ip-address" #192.168.1.3
export KUSER="admin-user"

# download the Kubernetes admin config for work dev
scp $KUSER@$SERVER1:/etc/rancher/rke2/rke2.yaml ~/.kube/dev-kube-context`
scp $KUSER@$SERVER2:/etc/rancher/rke2/rke2.yaml ~/.kube/prod-kube-context`

NOTE: The config location may be different based on the version of kubernetes installed

Context Configuration

After copying the config files over, the following sections need to be updated:
Cluster Section.

- cluster:
    server: https://192.168.1.x:6443
  name: dev-cluster

Users Section.

users:
- name: dev-admin

Contexts Section.

contexts:
- context:
    cluster: dev-cluster
    user: dev-admin
  name: dev-cluster-context
current-context: dev-cluster-context

Export KUBECONFIG

export KUBECONFIG="$HOME/.kube/dev-kube-context:$HOME/.kube/prod-kube-context"

Get Contexts: Run the command kubectl config get-contexts to get the contests

CURRENT   NAME                   CLUSTER        AUTHINFO     NAMESPACE
*         dev-cluster-context    dev-cluster    dev-admin    
          prod-cluster-context   prod-cluster   prod-admin

List Nodes in default dev-cluster-context

kubectl get nodes

NAME              STATUS   ROLES                       AGE     VERSION
dev-kube-master   Ready    control-plane,etcd,master   4d16h   v1.20.6+rke2r1
dev-kube-node1    Ready    <none>                      4d16h   v1.20.6+rke2r1
dev-kube-node2    Ready    <none>                      4d16h   v1.20.6+rke2r1

List Nodes in prod-cluster-context

kubectl config use-context prod-cluster-context
# Switched to context "prod-cluster-context".

kubectl config get-contexts
# CURRENT   NAME                   CLUSTER        AUTHINFO     NAMESPACE
#          dev-cluster-context    dev-cluster    dev-admin    
#*         prod-cluster-context   prod-cluster   prod-admin   

kubectl get nodes
#NAME               STATUS     ROLES                       AGE   VERSION
#prod-kube-master   Ready      control-plane,etcd,master   50m   v1.20.6+rke2r1
#prod-kube-node1    Ready      <none>                      47m   v1.20.6+rke2r1