Docs for K3s

docs/software/system_stats.md

@@ -8,6 +8,7 @@
 - [**RPi-Monitor - Web interface system stats**](#rpi-monitor)
 - [**Netdata - Web interface system stats**](#netdata)
 - [**Webmin - Remote system management with web interface**](#webmin)
+- [**K3s - Lightweight Kubernetes**](#k3s)
 
 ??? info "How do I run **DietPi-Software** and install **optimised software** items?"
     To install any of the **DietPi optimised software items** listed below run from the command line:
@@ -251,4 +252,52 @@ Official website: <https://webmin.com/>
 Official documentation: <https://doxfer.webmin.com/Webmin/Main_Page>  
 Wikipedia: <https://wikipedia.org/wiki/Webmin>
 
+
+## K3s
+
+Lightweight Kubernetes - The certified Kubernetes distribution built for IoT & Edge computing
+
+![K3s Logo](https://k3s.io/images/logo-k3s.svg){: width="300" height="116" loading="lazy"}
+
+=== "Before installation"
+
+    The default installation of K3s creates a single-node cluster.
+    If you want to have a multi-node setup, you need to configure the nodes to speak to the others.
+
+    In `/boot/dietpi.txt`, edit the `SOFTWARE_K3S_EXEC` parameter to set command (`server` or `agent`).
+    After the command, you can add other command-line parameters here.
+
+    Example:
+
+    ```
+    SOFTWARE_K3S_EXEC=server --disable=local-storage
+    ```
+
+    If you need to add many command-line parameters, it is recommended to put them in a file instead, 
+    keeping only the command (`server` or `agent`) in `/boot/dietpi.txt`.
+    During installation, if `/boot/dietpi-k3s.yaml` exists, it is copied to `/etc/rancher/k3s/config.yaml`, and used by K3s.
+    The format of this file is documented in the [K3s docs](https://rancher.com/docs/k3s/latest/en/installation/install-options/#configuration-file).
+
+=== "Connecting to your cluster"
+
+    When running in `server` mode, K3s generates a kubeconfig file at `/etc/rancher/k3s/k3s.yaml`.
+    Copy this to your client machine, and edit the `server` setting to point to the hostname of the server.
+
+    Place the file in the default location (`~/.kube/config`), or point to it using the `KUBECONFIG` environment-variable.
+
+    You should now be able to interact with your Kubernetes cluster using `kubectl`:
+
+    ```
+    kubectl get nodes
+    kubectl get pods -A
+    ```
+
+=== "View logs"
+
+    - Service: `journalctl -u k3s`
+
+
+Website: <https://k3s.io>
+
+
 [Return to the **Optimised Software list**](../../software/)