K3s is a lightweight, easy to install Kubernetes distribution geared towards resource-constrained environments and low touch operations. Some use cases in which k3s really shines are edge, ARM, IoT, and CI.
K3s from Rancher Labs is packaged as a single binary which is about 40 megabytes in size. Bundled in that single binary is everything needed to run Kubernetes, including the container runtime and any important host utilities like iptables, socat, and du. The only OS dependencies are the Linux kernel itself and a proper dev, proc, and sysfs mounts (this is done automatically on all modern distros). Cloud Native Computing Foundation (CNCF) has accepted the K3s as its Sandbox project in Aug'2020.
What is K3s?:
K3s is a fully compliant Kubernetes distribution with the following enhancements:
- Packaged as a single binary.
- Lightweight storage backend based on sqlite3 as the default storage mechanism. etcd3, MySQL, Postgres also still available.
- Wrapped in simple launcher that handles a lot of the complexity of TLS and options.
- Secure by default with reasonable defaults for lightweight environments.
- Simple but powerful “batteries-included” features have been added, such as: a local storage provider, a service load balancer, a Helm controller, and the Traefik ingress controller.
- Operation of all Kubernetes control plane components is encapsulated in a single binary and process. This allows K3s to automate and manage complex cluster operations like distributing certificates.
- External dependencies have been minimized (just a modern kernel and cgroup mounts needed). K3s packages required dependencies, including:
- Containerd
- Flannel
- CoreDNS
- CNI
- Host utilities (iptables, socat, etc)
- Ingress controller (traefik)
- Embedded service loadbalancer
- Embedded network policy controller
ref:
K3s, Lightweight Kubernetes - https://rancher.com/docs/k3s/latest/en/, https://www.infoworld.com/article/3342125/rancher-k3s-brings-kubernetes-to-iot-devices.html
K3s Architecture - https://rancher.com/docs/k3s/latest/en/architecture/
K3s github source code - https://github.com/rancher/k3s
K3s overview - https://rancher.com/blog/2019/2019-02-26-introducing-k3s-the-lightweight-kubernetes-distribution-built-for-the-edge/
Build a Kubernetes cluster using k3s via Ansible - https://github.com/rancher/k3s-ansible
Develop your cloud native use cases at the edge with K3s - https://www.cncf.io/webinars/develop-your-cloud-native-use-cases-at-the-edge-with-k3s/
Rancher Labs’ K3s Joins Cloud Native Computing Foundation as Sandbox Project - https://www.businesswire.com/news/home/20200826005093/en/Rancher-Labs%E2%80%99-K3s-Joins-Cloud-Native-Computing
