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k3s - Lightweight Kubernetes
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===============================================
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Lightweight Kubernetes. Easy to install, half the memory, all in a binary less than 100 MB.
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Great for:
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* Edge
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* IoT
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* CI
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* Development
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* ARM
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* Embedding k8s
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* Situations where a PhD in k8s clusterology is infeasible
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What is this?
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---
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k3s is a fully compliant Kubernetes distribution with the following changes:
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1. Packaged as a single binary.
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1. Lightweight storage backend based on sqlite3 as the default storage mechanism. etcd3, MySQL, Postgres also still available.
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1. Wrapped in simple launcher that handles a lot of the complexity of TLS and options.
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1. Secure by default with reasonable defaults for lightweight environments.
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1. Minimal to no OS dependencies (just a sane kernel and cgroup mounts needed). k3s packages required
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dependencies
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* containerd
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* Flannel
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* CoreDNS
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* CNI
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* Host utilities (iptables, socat, etc)
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* Ingress controller (traefik)
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* Embedded service loadbalancer
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* Embedded network policy controller
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What's with the name?
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--------------------
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We wanted an installation of Kubernetes that was half the size in terms of memory footprint. Kubernetes is a
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10 letter word stylized as k8s. So something half as big as Kubernetes would be a 5 letter word stylized as
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k3s. There is no long form of k3s and no official pronunciation.
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Documentation
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-------------
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Please see [the official docs site](https://rancher.com/docs/k3s/latest/en/) for complete documentation on k3s.
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Quick-Start - Install Script
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--------------
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The k3s `install.sh` script provides a convenient way for installing to systemd or openrc,
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to install k3s as a service just run:
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```bash
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curl -sfL https://get.k3s.io | sh -
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```
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A kubeconfig file is written to `/etc/rancher/k3s/k3s.yaml` and the service is automatically started or restarted.
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The install script will install k3s and additional utilities, such as `kubectl`, `crictl`, `k3s-killall.sh`, and `k3s-uninstall.sh`, for example:
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```bash
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sudo kubectl get nodes
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```
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`K3S_TOKEN` is created at `/var/lib/rancher/k3s/server/node-token` on your server.
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To install on worker nodes we should pass `K3S_URL` along with
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`K3S_TOKEN` or `K3S_CLUSTER_SECRET` environment variables, for example:
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```bash
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curl -sfL https://get.k3s.io | K3S_URL=https://myserver:6443 K3S_TOKEN=XXX sh -
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```
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Manual Download
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---------------
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1. Download `k3s` from latest [release](https://github.com/rancher/k3s/releases/latest), x86_64, armhf, and arm64 are supported.
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2. Run server.
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```bash
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sudo k3s server &
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# Kubeconfig is written to /etc/rancher/k3s/k3s.yaml
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sudo k3s kubectl get nodes
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# On a different node run the below. NODE_TOKEN comes from
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# /var/lib/rancher/k3s/server/node-token on your server
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sudo k3s agent --server https://myserver:6443 --token ${NODE_TOKEN}
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```
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