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

   # 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"

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:

   # 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