What

K3s is a fully compliant, lightweight version of Kubernetes created by Rancher K3s is a lightweight Kubernetes.

When to choose k3s over kubernets
Resource constraints: You are running on low-memory or low-CPU hardware.
Edge computing: You are deploying on IoT devices, Raspberry Pis, or remote cell towers.
Single-node clusters: You only need a simple, one-server setup.
Local development: You want a fast-booting cluster on your laptop.CI/CD pipelines: You need to spin up and tear down temporary clusters quickly for testing.

K3s Architecture

K3s retains the concept of master (also called server nodes) and worker (also called agent nodes), similar to Kubernetes.
However, it simplifies the architecture by removing some components and using lightweight alternatives.

Read differences below and Check kubernets Architecture

Difference in k3s and Kubernets Architecture

kubernets k3s
Server / Master Node Deamons in server node:
  API server
  Controller manager
  Scheduler
  etcd
Deamons in server node:
  API server(same)
  Controller manager(same)
  Scheduler(same)
  SQLite or etcd(K3s replaces etcd with SQLite by default for single-node clusters to reduce resource usage)
Agent Nodes / Worker Nodes Deamons in worker node:
  Kubelet
  Kube-proxy
  Container runtime (Docker)
Deamons in worker node:
  Kubelet
  Kube-proxy
  Container runtime (containerd or CRI-O)
Single-Node Clusters No
Requires separate master and worker nodes installation for high availability.
Yes
K3s is often deployed as a single-node cluster, where 1 node acts as both a server (control plane) and agent (worker)
High Availability (HA) multiple master and worker nodes same