k3s - Lightweight Kubernetes

Lightweight Kubernetes. Easy to install, half the memory, all in a binary less than 100 MB.

Great for:

• Edge
• IoT
• CI
• Development
• ARM
• Embedding k8s
• Situations where a PhD in k8s clusterology is infeasible

What is this?

k3s is a fully compliant Kubernetes distribution with the following changes:

1. Packaged as a single binary.
2. Lightweight storage backend based on sqlite3 as the default storage mechanism. etcd3, MySQL, Postgres also still available.
3. Wrapped in simple launcher that handles a lot of the complexity of TLS and options.
4. Secure by default with reasonable defaults for lightweight environments.
5. Minimal to no OS dependencies (just a sane kernel and cgroup mounts needed). k3s packages required dependencies
   • containerd
   • Flannel
   • CoreDNS
   • CNI
   • Host utilities (iptables, socat, etc)
   • Ingress controller (traefik)
   • Embedded service loadbalancer
   • Embedded network policy controller

What's with the name?

We wanted an installation of Kubernetes that was half the size in terms of memory footprint. Kubernetes is a 10 letter word stylized as k8s. So something half as big as Kubernetes would be a 5 letter word stylized as k3s. There is no long form of k3s and no official pronunciation.

Documentation

Please see the official docs site for complete documentation on k3s.

Quick-Start - Install Script

The k3s install.sh script provides a convenient way for installing to systemd or openrc, to install k3s as a service just run:

curl -sfL https://get.k3s.io | sh -

A kubeconfig file is written to /etc/rancher/k3s/k3s.yaml and the service is automatically started or restarted. The install script will install k3s and additional utilities, such as kubectl, crictl, k3s-killall.sh, and k3s-uninstall.sh, for example:

sudo kubectl get nodes

K3S_TOKEN is created at /var/lib/rancher/k3s/server/node-token on your server. To install on worker nodes we should pass K3S_URL along with K3S_TOKEN or K3S_CLUSTER_SECRET environment variables, for example:

curl -sfL https://get.k3s.io | K3S_URL=https://myserver:6443 K3S_TOKEN=XXX sh -

Manual Download

1. Download k3s from latest release, x86_64, armhf, and arm64 are supported.
2. Run server.

sudo k3s server &
# Kubeconfig is written to /etc/rancher/k3s/k3s.yaml
sudo k3s kubectl get nodes

# On a different node run the below. NODE_TOKEN comes from
# /var/lib/rancher/k3s/server/node-token on your server
sudo k3s agent --server https://myserver:6443 --token ${NODE_TOKEN}