Installing and configuring a K3s edge cluster

Introduction

This content provides a summary of how to install k3s (rancher), a lightweight and small Kubernetes cluster, on a recent Ubuntu LTS distribution. For more information, see the k3s documentation .

Pre-requisites

Architecture must be either x86_64 (amd64) or arm64
Operating system must be modern Linux variant with 64-bit and systemd support

Note: If installed, uninstall kubectl before completing the following steps.

Installing

Either login as root or elevate to root with sudo -i
Confirm that the full hostname of your machine contains at least two dots:
```
hostname
```
If the full hostname of your machine contains fewer than two dots, change the hostname:
```
hostnamectl set-hostname <your-new-hostname-with-2-dots>
```
For more information, see github issue .
Install k3s:
```
curl -sfL https://get.k3s.io | sh -
```

Create the image registry service:

Create the persistent volume claim:

kubectl apply -f https://raw.githubusercontent.com/open-horizon/open-horizon.github.io/master/docs/installing/k3s-persistent-claim.yaml

Verify that the persistent volume claim was created and is in “Pending” status
```
kubectl get pvc
```

Create the registry deployment and service:

kubectl apply -f https://raw.githubusercontent.com/open-horizon/open-horizon.github.io/master/docs/installing/k3s-registry-deployment.yaml

Verify that the service was created:

kubectl get deployment
kubectl get service

Which will issue a response similar to:

NAME              READY   UP-TO-DATE   AVAILABLE   AGE
docker-registry   1/1     1            1           21s
NAME                      TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes                ClusterIP   10.43.0.1      <none>        443/TCP          3h46m
docker-registry-service   NodePort    10.43.46.175   <none>        5000:31466/TCP   67s

Define the registry endpoint:

export REGISTRY_ENDPOINT=$(kubectl get service docker-registry-service | grep docker-registry-service | awk '{print $3;}'):5000

To verify that it was set properly:

echo $REGISTRY_ENDPOINT

Which will respond with something similar to:

10.43.46.175:5000

Add it to K3s configuration:

cat << EOF >> /etc/rancher/k3s/registries.yaml
mirrors:
  "$REGISTRY_ENDPOINT":
    endpoint:
      - "http://$REGISTRY_ENDPOINT"
EOF

To verify that it wrote the file properly:

cat /etc/rancher/k3s/registries.yaml

Which will respond with something similar to:

mirrors:
  "10.43.46.175:5000":
    endpoint:
      - "http://10.43.46.175:5000"

Restart k3s to pick up the change to the K3s configuration:
```
systemctl restart k3s
```

Define this registry in Docker as an insecure registry:
1. Install Docker (if not already installed):
  
  NOTE: If docker --version responds with a version number, then it is installed.
```
curl -fsSL get.docker.com | sh
```
2. Create or add to /etc/docker/daemon.json (replacing <registry-endpoint> with the value of the $REGISTRY_ENDPOINT environment variable you obtained in a previous step).
```
{
  "insecure-registries": [ "<registry-endpoint>" ]
}
```
3. Restart Docker to pick up the change:
```
systemctl restart docker
```

What’s next

Installing the Cluster Agent