single-node

Single Node K3s Installation on Ubuntu 22.04 LTS

This guide provides simple steps to set up a single-node K3s cluster on Ubuntu 22.04 LTS.

Prerequisites

• Ubuntu 22.04 LTS server
• User with sudo privileges
• Internet connectivity

Installation Steps

1. Update the System

Update your system packages to the latest versions.

sudo apt update && sudo apt upgrade -y

2. Install K3s

Use the official installation script to install K3s.

curl -sfL https://get.k3s.io | sh -

This will install K3s and start the service automatically.

3. Verify the Installation

Check the status of the K3s service.

sudo systemctl status k3s

You should see that the service is active and running.

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Testing the Cluster

To ensure that your K3s cluster is up and running, perform the following tests.

1. Check Node Status

List all the nodes in the cluster.

kubectl get nodes

You should see output similar to:

NAME        STATUS   ROLES                  AGE     VERSION
your-node   Ready    control-plane,master   5m      v1.XX

2. Deploy a Test Application

Deploy a simple Nginx deployment to test cluster functionality.

kubectl create deployment nginx --image=nginx

3. Expose the Deployment

Expose the Nginx deployment via a LoadBalancer service.

kubectl expose deployment nginx --type=LoadBalancer --port=80 --target-port=80

Note: K3s includes a built-in service load balancer (klipper-lb), which allows the LoadBalancer service type to work on a single-node cluster.

4. Verify the Service

List the services to get the external IP address.

kubectl get services

You should see output like:

NAME         TYPE           CLUSTER-IP     EXTERNAL-IP    PORT(S)        AGE
kubernetes   ClusterIP      10.43.0.1      <none>         443/TCP        10m
nginx        LoadBalancer   10.43.0.123    <node-ip>      80:31234/TCP   1m

Note: The <node-ip> should be the IP address of your K3s server. If EXTERNAL-IP shows <pending>, wait a few moments and run the command again.

5. Test Access to Nginx

Use curl to access the Nginx service using the external IP.

curl http://<node-ip>:80

Replace <node-ip> with the external IP address of your node (e.g., 192.168.1.10).

You should see the default Nginx welcome page HTML.

6. Clean Up

Delete the test deployment and service.

kubectl delete service nginx
kubectl delete deployment nginx

Access K3s from Another Machine (Optional)

If you want to access the cluster from another machine, copy the kubeconfig file.

First, display the kubeconfig file.

sudo cat /etc/rancher/k3s/k3s.yaml

Copy the content and save it to ~/.kube/config on your local machine.

Replace 127.0.0.1 with the IP address of your K3s server.

Uninstall K3s (Optional)

If you need to remove K3s, run the uninstall script.

/usr/local/bin/k3s-uninstall.sh

Conclusion

You have successfully set up and tested a single-node K3s cluster on Ubuntu 22.04 LTS. You can now deploy your Kubernetes workloads on this cluster.