K3s

Introduction

K3s is a lightweight, fully compliant Kubernetes distribution that is easy to install and manage. This guide provides step-by-step instructions for installing a K3s cluster, managing nodes, and uninstalling K3s.

Prerequisites

• A Linux-based system with internet access.
• Root or sudo privileges.
• hardware resource requirement can be found here

configure hostname and hosts

• assuming we have 4 nodes and configured with hostnames: k3s1, k3s2, k3s3 and k3s4

  • hostnamectl set-hostname <hostname>
    

• add following lines to /etc/hosts on each node
  • change ip according to your own environment

  • 192.168.1.104 k3s1
    192.168.1.105 k3s2
    192.168.1.106 k3s3
    192.168.1.107 k3s4
    

Installing K3s Cluster

0. configure /etc/rancher/k3s/registries.yaml on each node

   • mirrors:
       docker.io:
         endpoint:
           - "https://dockerproxy.net"
     

1. initialize first control panel

   • curl -sfL https://rancher-mirror.rancher.cn/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn sh -s - server --cluster-init --flannel-backend=vxlan --node-taint "node-role.kubernetes.io/control-plane=true:NoSchedule"
     

2. get join-token from control panel

   • cat /var/lib/rancher/k3s/server/node-token
     

3. initialize workers(agent in k3s) and join to control panel with the token

   • curl -sfL https://rancher-mirror.rancher.cn/k3s/k3s-install.sh | INSTALL_K3S_MIRROR=cn K3S_URL=https://k3s1:6443 K3S_TOKEN=<join-token> sh -
     

Copy configuration

• mkdir -p $HOME/.kube
  cp /etc/rancher/k3s/k3s.yaml $HOME/.kube/config
  

Uninstalling K3s Cluster

1. remove worker(k3s-agent) from cluster
   • cordon a node: prevent new pods from being scheduled to the node

     • kubectl cordon <node-name>
       

   • drain a node: move all pods to other nodes

     • kubectl drain <node-name> --ignore-daemonsets --delete-emptydir-data
       # check if all pods are moved to other nodes
       #kubectl get pods -o wide --all-namespaces | grep <node-name>
       

   • delete the node

     • kubectl delete node <node-name>
       

2. uninstall k3s from worker(k3s-agent node)

   • systemctl stop k3s-agent
     /usr/local/bin/k3s-agent-uninstall.sh
     /usr/local/bin/k3s-uninstall.sh
     

3. uninstall k3s from control panel(k3s-server node)

   • systemctl stop k3s
     /usr/local/bin/k3s-uninstall.sh