Update k0smotron in Cluster API integrated cluster#

To update k0smotron cluster deployed with Cluster API, you need to update the k0s version and machine names in the YAML configuration file:

Localize the configuration of deployed k0smotron cluster in your repository. For example:

apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  name: docker-test
  namespace: default
spec:
  clusterNetwork:
    pods:
      cidrBlocks:
      - 192.168.0.0/16
    serviceDomain: cluster.local
    services:
      cidrBlocks:
      - 10.128.0.0/12
  controlPlaneRef:
    apiVersion: controlplane.cluster.x-k8s.io/v1beta1
    kind: K0smotronControlPlane
    name: docker-test-cp
  infrastructureRef:
    apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
    kind: DockerCluster
    name: docker-test
---
apiVersion: controlplane.cluster.x-k8s.io/v1beta1
kind: K0smotronControlPlane
metadata:
  name: docker-test-cp
spec:
  version: v1.27.2-k0s.0

2. Configure persistence to prevent data loss. For example:

 ---
 apiVersion: controlplane.cluster.x-k8s.io/v1beta1
 kind: K0smotronControlPlane
 metadata:
   name: docker-test-cp
 spec:
   version: v1.27.2-k0s.0
   persistence:
     type: hostPath
     hostPath: "/tmp/kmc-test" # k0smotron will mount a basic hostPath volume to avoid data loss.

Using the hostPath volume type introduces many security risks. Avoid configuring persistence for volumes of the hostPath type. Learn more from official Kubernetes documentation: hostPath.

Change all the k0s versions to the target one. For example:

apiVersion: controlplane.cluster.x-k8s.io/v1beta1
kind: K0smotronControlPlane
metadata:
  name: cp-test
spec:
  version: v1.28.7-k0s.0 # new k0s version

In the same configuration, replace the names of machines running the old k0smotron version with the new names to create machines for the target k0smotron version. For example:

---
apiVersion: cluster.x-k8s.io/v1beta1
kind: Machine
metadata:
  name:  docker-test-1 # new machine
  namespace: default
spec:
  version: v1.28.7 # new version
  clusterName: docker-test
  bootstrap:
    configRef:
      apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
      kind: K0sWorkerConfig
      name: docker-test-1 # new machine
  infrastructureRef:
    apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
    kind: DockerMachine
    name: docker-test-1 # new machine
---
apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
kind: K0sWorkerConfig
metadata:
  name: docker-test-1 # new machine
  namespace: default
spec:
  version: v1.28.7+k0s.0 # new version

Update the resources:
```
kubectl apply -f ./path-to-file.yaml
```
Remove the machines running the old k0smotron version:
```
kubectl delete machine docker-test-0
```

The update procedure is completed, you now have the target version of k0smotron.