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

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

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.

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

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 -

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}