k3s-io/k3s

K3s is a lightweight distribution of Kubernetes, a system for running and managing containerized applications across a cluster of servers. Standard Kubernetes is powerful but complex to install and resource-hungry, which makes it impractical on small machines, edge devices (computers deployed in remote locations), Raspberry Pi-style ARM hardware, or CI (automated testing) environments where you want a real cluster without the overhead. K3s solves this by packaging everything needed for a working Kubernetes cluster into a single binary under 100 MB that uses roughly half the memory of full Kubernetes. It is not a fork, it implements the same Kubernetes API fully and passes official conformance tests, meaning anything that runs on regular Kubernetes runs on K3s unchanged. The main differences are that K3s bundles its own container runtime (containerd), networking (Flannel), DNS (CoreDNS), load balancer, ingress (Traefik), and storage provisioner into one distribution, and it defaults to SQLite instead of etcd for storing cluster state (though etcd, MySQL, MariaDB, and Postgres are also supported). It also packs all components into a single process, which dramatically reduces memory overhead compared to running each piece separately. Installation is a single curl command that downloads the binary, sets up the system service, and starts the cluster in seconds. Worker nodes join by pointing at the server node's address with a token. You would choose K3s when you need genuine Kubernetes behavior, not a simplified emulator, on hardware or environments where full Kubernetes is too heavy: IoT devices, home lab servers, edge computing locations, development laptops, or automated test pipelines where you want a fresh cluster spun up quickly. It is written in Go and is an official CNCF (Cloud Native Computing Foundation) project.