Deploy Highly-Available Kubernetes with k3s + k3sup

k3s is a CNCF Cloud Native Landscape project that facilitates the quick-and-easy deployment of Kubernetes ("k8s"), which has allowed "k8s" to run on smaller devices, and more resource-constrained environments.

TL;DR?: k3s is a great little all-in-one package of software(s) that allow you to be able to run Kubernetes without needing a large number of processor cores, or a large amount of RAM. You can run this on Raspberry Pis, Mini PCs, and more.

Deploy your Virtual Machines

First, you'll need virtual machines for your k3s cluster to run on.

1. Deploy VMs Must deploy a minimum of 3 for Quorum (n/2)+1
2. Copy SSH Keys to Machines

#!/bin/bash

# Define the array of IP addresses
ips=("192.168.1.151" "192.168.1.152" "192.168.1.153") # Don't worry, these aren't my real nodes... ;)
first_ip="${ips[0]}"
ssh_key="~/.ssh/devbox"

# Loop over the array of IPs
for i in "${!ips[@]}"; do
ip="${ips[$i]}"

# Copy the SSH Key to the Server
ssh-copy-id -i ~/.ssh/devbox johndoe@"$ip"

# Add 'johndoe ALL=(ALL) NOPASSWD: ALL' to the sudoers file
ssh -i devbox johndoe@"$ip" "echo 'johndoe ALL=(ALL) NOPASSWD: ALL' | sudo tee -a /etc/sudoers.d/johndoe"

done

3. Enable password-less sudo sudo visudo add johndoe ALL=(ALL) NOPASSWD: ALL` to the end of the file
4. Install k3s using this guide https://ma.ttias.be/deploying-highly-available-k3s-k3sup/#create-a-multi-master-ha-setup
5. Install prerequisites for longhorn using this script:

#!/bin/bash

Update and install dependencies

echo "Updating system and installing prerequisites..." sudo apt update -y && sudo apt upgrade -y sudo apt install -y curl gnupg2 software-properties-common apt-transport-https ca-certificates

Configure sysctl for Kubernetes networking

echo "Configuring sysctl for Kubernetes networking..." cat <<EOF | sudo tee /etc/sysctl.d/kubernetes.conf net.bridge.bridge-nf-call-ip6tables = 1 net.bridge.bridge-nf-call-iptables = 1 EOF sudo sysctl --system

Install Longhorn prerequisites

echo "Installing Longhorn prerequisites..." sudo apt install -y open-iscsi sudo systemctl enable iscsid sudo systemctl start iscsid sudo apt-get install cifs-utils sudo apt-get install nfs-common

Verify installation

echo "Verifying installation..." kubectl version --client kubeadm version containerd --version systemctl is-active iscsid

echo "Prerequisites installed successfully. Please ensure Kubernetes cluster is initialized before deploying Longhorn."

6. Install Longhorn:
   `helm install longhorn longhorn/longhorn --namespace longhorn-system --create-namespace --version 1.7.2`

Inspiration Articles

• Geniar, M. (2020, April 27). Deploying a highly-available K3s with K3sup. https://ma.ttias.be/deploying-highly-available-k3s-k3sup/#create-a-multi-master-ha-setup