Posts tagged: k3s

The k3s system-upgrade controller is a fantastic tool for upgrading k3s automatically. It has done a fantastic job for me every time I’ve used it. Today I ran it on a cluster that needed to upgrade several minors and I learned that the controller does not pick up on changes to the channel url if you change from minor to minor.

The solution I came up with was to name the plan with the version it supports. Then on each patch upgrade, change both the plan name and the channel. I use gitops with argocd, it automcatically cleaned up old plans, created new plans, and the system-upgrade-controller picked up the plan and started applying immediately.

# Server plan
apiVersion: upgrade.cattle.io/v1
kind: Plan
metadata:
  name: server-plan-v1.33 # <- This is important if you want to change the channel name
  namespace: system-upgrade
spec:
  concurrency: 1
  cordon: true
  nodeSelector:
    matchExpressions:
    - key: node-role.kubernetes.io/control-plane
      operator: In
      values:
      - "true"
  serviceAccountName: system-upgrade
  upgrade:
    image: rancher/k3s-upgrade
  channel: https://update.k3s.io/v1-release/channels/v1.33
---
# Agent plan
apiVersion: upgrade.cattle.io/v1
kind: Plan
metadata:
  name: agent-plan-v1.33 # <- This is important if you want to change the channel name
  namespace: system-upgrade
spec:
  concurrency: 1
  cordon: true
  nodeSelector:
    matchExpressions:
    - key: node-role.kubernetes.io/control-plane
      operator: DoesNotExist
  prepare:
    args:
    - prepare
    - server-plan
    image: rancher/k3s-upgrade
  serviceAccountName: system-upgrade
  upgrade:
    image: rancher/k3s-upgrade
  channel: https://update.k3s.io/v1-release/channels/v1.33

I’d love to see a better way if you have a way to upgrade through minors, or manually control the minor of your cluster let me know.

After first setting up a new k3s instance your kubeconfig file will be located in /etc/rancher/k3s/k3s.yaml.

You cans use it from here by setting $KUBECONFIG to that file.

export KUBECONFIG=/etc/rancher/k3s/k3s.yaml

Or you can copy it to ~/.kube/config

cp /etc/rancher/k3s/k3s.yaml ~/.kube/config

If you have installed k3s on a remote server and need the config on your local machine then you will need to modify the server address to reflect the remote server.

scp user@<server-ip>:/etc/rancher/k3s/k3s.yaml ~/.kube/config

only do this if you don’t already have a ~/.kube/config file, otherwise copy it to a new file and set your $KUBECONFIG env variable to use it.

Now you will need to open that file and change the server address, making sure to keep the port number.

apiVersion: v1
clusters:
  - cluster:
      certificate-authority-data: ****
      server: https://<server-ip>:6443
    name: default