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k3s - 5 less than k8s

Lightweight Kubernetes. Easy to install, half the memory, all in a binary less than 40mb.

Great for:

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

What is this?

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

  1. Legacy, alpha, non-default features are removed. Hopefully, you shouldn't notice the stuff that has been removed.
  2. Removed most in-tree plugins (cloud providers and storage plugins) which can be replaced with out of tree addons.
  3. Add sqlite3 as the default storage mechanism. etcd3 is still available, but not the default.
  4. Wrapped in simple launcher that handles a lot of the complexity of TLS and options.
  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)

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}