K3S Lightweight Kubernetes

Why k3s

Is a single binary lightweight kubernetes service. It can run on any pc, raspberry or in a edge iot device: it use less memory as possibile to leave more resources for your services.

Rancher K3S can be configured as single node cluster or high availability production cluster.

Install cluster in HA

Instal master nodes

To have a HA cluster you need almost 3 master as control panel.

K3S, after the release v1.19.5+k3s1, came with a embeded etcd cluster service. But if you want you can configure an external DB such as: mysql, postress or etcd.

For this example we use embeded etcd service.

# First master node
curl -sfL https://get.k3s.io | sh -s - server \
--write-kubeconfig-mode 644 \
--token <my super secret token> \
--cluster-init 

After launching the first server, join the second and third servers to the cluster using the shared secret:

curl -sfL https://get.k3s.io | sh -s - server \
--write-kubeconfig-mode 644 \
--token <my super secret token> \
--server https://<ip or hostname of server1>:6443

Instal aget nodes

curl -sfL https://get.k3s.io | K3S_TOKEN=<my super secret token> \
K3S_KUBECONFIG_MODE="644" \
K3S_URL=https://<ip or hostname of server1>:6443 sh -

Check nodes status

Run into a node the following command to check nodes

kubectl get nodes

NAME     STATUS   ROLES                       AGE   VERSION
k3s-01   Ready    control-plane,etcd,master   33m   v1.23.8+k3s2
k3s-02   Ready    control-plane,etcd,master   30m   v1.23.8+k3s2
k3s-03   Ready    control-plane,etcd,master   26m   v1.23.8+k3s2
k3s-04   Ready    <none>                      19s   v1.23.8+k3s2

Export kubectl configuration

In order to connecto to cluster from your computer you need to export the configuration.

K3S save the kubeconfig into /etc/rancher/k3s/k3s.yaml. You need to copy the file content and change the server ip with the real IP or name of server.

Then you can connect

kubectl --kubeconfig ~/kubeconfig.yaml get nodes

Your HA cluster is now up and running.

🎉 Happy deploy