Prerequisites

1. Access to all nodes of the cluster through one of the following methods
   - Rancher
   - SSH protocol
   - AWS Session Manager

2. The K3s version tag you wish to upgrade to: https://github.com/k3s-io/k3s/releases

3. The system-upgrade-controller file that will be used to upgrade the K3s cluster:
   https://assets.master.k3s.getvisibility.com/system-upgrade-controller/v0.10.0/system-upgrade-controller.yaml

Focus/Synergy services

Updates and custom settings are automatically applied to all backend services using Fleet as long as the cluster has access to the public internet and can connect to the management server.

In case there’s no internet connection or the management server is down, the cluster agent will keep trying to reach the management server until a connection can be established.

Upgrading K3s

1. Log in to Rancher or one of the master nodes of the cluster to use kubectl CLI

2. List the node name and the K3s version:

   kubectl get nodes

3. Add the label k3s-upgrade=true to the nodes:
   Note: In the case of a multi-node cluster, each node will be updated with the label mentioned above

   kubectl label node --all k3s-upgrade=true

4. Deploy the system-upgrade-controller :

   kubectl apply -f https://assets.master.k3s.getvisibility.com/system-upgrade-controller/v0.10.0/system-upgrade-controller.yaml

5. Create upgrade-plan.yaml file.
   Note: the key version has the version of the K3s that the cluster will be upgraded to.

   cat > upgrade-plan.yaml << EOF
   ---
   apiVersion: upgrade.cattle.io/v1
   kind: Plan
   metadata:
     name: k3s-latest
     namespace: system-upgrade
   spec:
     concurrency: 1
     version: v1.24.9+k3s2
     nodeSelector:
       matchExpressions:
         - {key: k3s-upgrade, operator: Exists}
     serviceAccountName: system-upgrade
     upgrade:
       image: docker.io/rancher/k3s-upgrade
   EOF

6. Run the upgrade plan.
   The upgrade controller should watch for this plan and execute the upgrade on the labeled nodes

   kubectl apply -f upgrade-plan.yaml

7. Once the plan is executed, all pods will restart and will take a few minutes to recover.
   Check the status of all the pods:

   watch kubectl get pods -A

8. Check if the K3s version has been upgraded:

   kubectl get nodes

9. Delete the system-upgrade-controller :

   kubectl delete -f https://assets.master.k3s.getvisibility.com/system-upgrade-controller/v0.10.0/system-upgrade-controller.yaml

Certificates

By default, certificates in K3s expire in 12 months. If the certificates are expired or have fewer than 90 days remaining before they expire, the certificates are rotated when K3s is restarted.

Demo Video

Here is the demo video that showcases the steps that need to be performed to upgrade K3s: