Overview

This series teaches K3s — the lightweight Kubernetes distribution by Rancher — through heavily annotated, self-contained examples. Each example focuses on a single K3s or Kubernetes concept and includes inline annotations explaining what each command or manifest directive does, why it matters, and what cluster state results from it.

K3s packages a full Kubernetes control plane into a single ~70 MB binary. It uses containerd instead of Docker, embeds Traefik as an ingress controller, ships local-path-provisioner for storage, and bundles CoreDNS, Flannel CNI, and Klipper load balancer — all with zero external dependencies for a single-node install. This series covers K3s v1.35.4+k3s1 running Kubernetes v1.35.4.

Series Structure

The examples are organized into three levels based on complexity:

• Beginner — Installation, core workload types, networking basics, storage, health checks, and K3s-specific features like the auto-manifest directory and config file (Examples 1-28)
• Intermediate — High availability setup, CNI replacement, HelmChart CRD, cert-manager TLS, MetalLB, RBAC, NetworkPolicy, autoscaling, Longhorn storage, and workload placement (Examples 29-57)
• Advanced — GitOps with Flux CD, multi-cluster with Rancher, policy enforcement with OPA Gatekeeper, observability stacks, cluster backup/restore, custom operators, and production hardening (Examples 58-85)

Structure of Each Example

Every example follows a consistent five-part format:

1. Brief Explanation — what the K3s concept addresses and why it matters (2-3 sentences)
2. Mermaid Diagram — visual representation of cluster topology, traffic flow, or component relationships (when appropriate)
3. Heavily Annotated Code — shell commands or YAML manifests with # => comments documenting each step and its cluster-state effect
4. Key Takeaway — the core insight to retain from the example (1-2 sentences)
5. Why It Matters — production relevance and real-world impact (50-100 words)

Prerequisites

These examples assume you have:

• A Linux host (Ubuntu 22.04 or Debian 12 recommended) with at least 1 CPU and 512 MB RAM
• sudo access for installation commands
• Familiarity with basic shell commands and YAML syntax
• Understanding of core Kubernetes concepts (Pod, Deployment, Service) at a conceptual level

How to Use This Series

Each page presents annotated shell sessions and YAML manifests. Read the # => annotations alongside the commands to understand both the mechanics and the intent. The examples within each level build progressively, so reading sequentially within a level gives the fullest understanding.