K3s is a lightweight, easy-to-install distribution of Kubernetes designed for resource-constrained environments, such as edge computing, IoT devices, and development/testing environments. It is developed by Rancher Labs, an organization known for its Kubernetes management platform.
In this tutorial, we will show you how to install Kubernetes using K3s on Ubuntu 22.04.
Step 1 – Install K3s
First, install the curl package for a smooth K3s installation.
apt install curl -y
Next, use the curl command to download and run the K3s installation script.
curl -sfL https://get.k3s.io | sh -
Once K3s has been installed, you can verify the K3s service using the following command.
systemctl status k3s
Output:
● k3s.service - Lightweight Kubernetes
Loaded: loaded (/etc/systemd/system/k3s.service; enabled; vendor preset: enabled)
Active: active (running) since Sat 2024-03-23 03:46:43 UTC; 7s ago
Docs: https://k3s.io
Process: 1860 ExecStartPre=/bin/sh -xc ! /usr/bin/systemctl is-enabled --quiet nm-cloud-setup.service 2>/dev/null (code=exited, status=0/SUCCESS)
Process: 1862 ExecStartPre=/sbin/modprobe br_netfilter (code=exited, status=0/SUCCESS)
Process: 1863 ExecStartPre=/sbin/modprobe overlay (code=exited, status=0/SUCCESS)
Main PID: 1864 (k3s-server)
Tasks: 29
Memory: 522.4M
CPU: 47.856s
CGroup: /system.slice/k3s.service
├─1864 "/usr/local/bin/k3s server"
└─1894 "containerd " "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" "" ">
Mar 23 03:46:49 ubuntu22 k3s[1864]: time="2024-03-23T03:46:49Z" level=error msg="error syncing 'kube-system/traefik-crd': handler helm-controller-chart-registration: h>
Mar 23 03:46:49 ubuntu22 k3s[1864]: I0323 03:46:49.689460 1864 event.go:307] "Event occurred" object="kube-system/traefik-crd" fieldPath="" kind="HelmChart" apiVers>
Mar 23 03:46:49 ubuntu22 k3s[1864]: I0323 03:46:49.694891 1864 event.go:307] "Event occurred" object="kube-system/traefik" fieldPath="" kind="HelmChart" apiVersion=>
Mar 23 03:46:49 ubuntu22 k3s[1864]: I0323 03:46:49.698154 1864 event.go:307] "Event occurred" object="kube-system/traefik" fieldPath="" kind="HelmChart" apiVersion=>
Mar 23 03:46:49 ubuntu22 k3s[1864]: I0323 03:46:49.699433 1864 event.go:307] "Event occurred" object="kube-system/traefik-crd" fieldPath="" kind="HelmChart" apiVers>
Mar 23 03:46:50 ubuntu22 k3s[1864]: time="2024-03-23T03:46:50Z" level=info msg="Stopped tunnel to 127.0.0.1:6443"
Mar 23 03:46:50 ubuntu22 k3s[1864]: time="2024-03-23T03:46:50Z" level=info msg="Connecting to proxy" url="wss://209.23.13.14:6443/v1-k3s/connect"
Mar 23 03:46:50 ubuntu22 k3s[1864]: time="2024-03-23T03:46:50Z" level=info msg="Proxy done" err="context canceled" url="wss://127.0.0.1:6443/v1-k3s/connect"
Mar 23 03:46:50 ubuntu22 k3s[1864]: time="2024-03-23T03:46:50Z" level=info msg="error in remotedialer server [400]: websocket: close 1006 (abnormal closure): unexpecte>
Mar 23 03:46:50 ubuntu22 k3s[1864]: time="2024-03-23T03:46:50Z" level=info msg="Handling backend connection request [ubuntu22]"
Step 2 – Access Kubernetes Cluster
You will need to configure kubectl to access and interact with the Kubernetes cluster via the command line.
First, create a directory to store kubectl configuration.
mkdir ~/.kube
Next, copy the Kubernetes configuration file inside the .kube directory.
cp /etc/rancher/k3s/k3s.yaml ~/.kube/config chmod 600 ~/.kube/config
Next, expose the path of the kubectl configuration file.
export KUBECONFIG=~/.kube/config
Next, verify the Kubernetes cluster nodes using the kubectl command.
kubectl get nodes
Output.
NAME STATUS ROLES AGE VERSION ubuntu22 Ready control-plane,master 51s v1.28.7+k3s1
You can also see the Kubernetes cluster information using the following command.
kubectl cluster-info
Output:
Kubernetes control plane is running at https://127.0.0.1:6443 CoreDNS is running at https://127.0.0.1:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy Metrics-server is running at https://127.0.0.1:6443/api/v1/namespaces/kube-system/services/https:metrics-server:https/proxy
Step 3 – Create an Nginx Deployment
To validate the Kubernetes installation, we will deploy a Nginx-based application and expose it via NodePort.
First, create an Nginx deployment using the following command.
kubectl create deployment nginx-app --image nginx --replicas 2
Next, verify the Nginx deployment using the following command.
kubectl get deployment nginx-app
Output.
NAME READY UP-TO-DATE AVAILABLE AGE nginx-app 2/2 2 2 10s
Next, verify the Nginx pods using the following command.
kubectl get pods
Output:
NAME READY STATUS RESTARTS AGE nginx-app-5777b5f95-lhcpp 1/1 Running 0 22s nginx-app-5777b5f95-2j6ld 1/1 Running 0 22s
Next, expose the nginx-app deployment using NodePort.
kubectl expose deployment nginx-app --type NodePort --port 80
Next, get the IP address of nginx-app using the following command:
kubectl get svc nginx-app
Output:
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE nginx-app NodePort 10.43.162.54 80:31588/TCP 5s
Now, use the IP address from the above output and run the curl command to access the nginx-app.
curl http://10.43.162.54
If everything is fine, you will see the following output:
<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
html { color-scheme: light dark; }
body { width: 35em; margin: 0 auto;
font-family: Tahoma, Verdana, Arial, sans-serif; }
</style>
</head>
<body>
<h1>Welcome to nginx!</h1>
<p>If you see this page, the nginx web server is successfully installed and
working. Further configuration is required.</p>
<p>For online documentation and support please refer to
<a href="http://nginx.org/">nginx.org</a>.<br/>
Commercial support is available at
<a href="http://nginx.com/">nginx.com</a>.</p>
<p><em>Thank you for using nginx.</em></p>
</body>
</html>
Conclusion
Overall, K3s offers a compelling solution for scenarios where a full-fledged Kubernetes deployment may be impractical or overly resource-intensive. Its lightweight design, ease of installation, and focus on security make it an attractive choice for edge computing, IoT deployments, and development/testing environments. You can now easily deploy Kubernetes cluster using K3s on dedicated server hosting from Atlantic.Net!
