Setting Up a K3s Kubernetes Cluster

Setting Up a K3s Kubernetes Cluster

K3s is a lightweight, certified Kubernetes distribution designed for resource-constrained environments like edge devices, IoT, and home labs. This guide will walk you through setting up a production-ready K3s cluster.

Prerequisites

  • At least two machines (physical or virtual) for high availability
  • Ubuntu 20.04 LTS or newer
  • At least 2GB RAM per node
  • 20GB+ storage per node
  • Network connectivity between all nodes

Installing the Server Node

First, let’s install the primary server node:

curl -sfL https://get.k3s.io | sh -s - server \
    --cluster-init \
    --tls-san=server-ip-or-hostname \
    --disable traefik \
    --disable servicelb

This initializes the cluster with:

  • HA enabled with --cluster-init
  • Custom TLS SAN for API server
  • Disabled default traefik ingress (we’ll use Nginx)
  • Disabled default ServiceLB (we’ll use MetalLB)

Installing Agent Nodes

On each worker node, run:

curl -sfL https://get.k3s.io | K3S_URL=https://server-ip:6443 K3S_TOKEN=node-token sh -

Replace server-ip with your server’s IP and get the token from /var/lib/rancher/k3s/server/node-token on the server.

Adding High Availability

For HA, add additional server nodes:

curl -sfL https://get.k3s.io | sh -s - server \
    --server https://first-server-ip:6443 \
    --token node-token \
    --tls-san=this-server-ip \
    --disable traefik \
    --disable servicelb

Setting Up Persistent Storage

We’ll use Longhorn for distributed storage:

kubectl apply -f https://raw.githubusercontent.com/longhorn/longhorn/master/deploy/longhorn.yaml

Longhorn provides replicated block storage across your nodes for high availability.

Next Steps

After setting up your cluster, you might want to:

  1. Install a proper ingress controller (Nginx, Traefik)
  2. Set up a load balancer (MetalLB)
  3. Configure monitoring with Prometheus and Grafana
  4. Implement GitOps with Flux or ArgoCD

Stay tuned for detailed guides on each of these topics!

This guide provides a starting point for your journey with K3s Kubernetes. In future posts, we’ll dive deeper into advanced configurations.