Upgrade Kubernetes Version

This guide outlines the steps to upgrade the Kubernetes version of a cluster, specifically demonstrating how to change the version using a configuration file.

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Upgrading a Kubernetes cluster

Upgrading a Kubernetes cluster is essential to maintain security, stability, and compatibility.Like Kubernetes itself, we adhere to the version skew policy and only allow upgrades between releases that differ by a single minor version. This ensures compatibility between components, reduces the risk of instability, and keeps the cluster in a supported and secure state.

For more information about the Version Skew Policy, see the official Kubernetes documentation:
Click here

Use the following steps to upgrade the Kubernetes version of a cluster.

Kubernetes Version Upgrade Process:

Prerequisites

KOSI Login Recommendation

Before performing any action with kubeopsctl, it is recommended to do a login with kosi. Refer to the official KOSI documentation for details here.

1. Pull required KOSI packages on your ADMIN

If you do not specify a parameter, the Kubernetes version 1.32.2 will be pulled.
With parameter --kubernetesVersion 1.34.1 you can pull an older Kubernetes version.
Available Kubernetes versions are 1.32.2 , 1.32.3 , 1.32.9 . 1.32.10 . 1.33.3 . 1.33.5 . 1.34.1 . 

kubeopsctl pull --kubernetesVersion <x.xx.x>

2. Change your target version inside the cluster-values

3. Start the upgrade

kubeopsctl apply -f cluster-values.yaml

Example 1 - Upgrade all nodes in the cluster to a specific version

In this example, a cluster is upgraded from Kubernetes version v1.33.5 to v1.34.1.

1. Pull required KOSI packages on your ADMIN

Pull the kubernetes v1.34.1 packages on your ADMIN machine.

kubeopsctl pull --kubernetesVersion 1.34.1

2. Update the target version in cluster-values.yaml

Adjust your cluster-values.yaml according to the example below. Make sure you set:

  • The current Kubernetes version in kubernetesVersion.
  • The target Kubernetes version in the kubeVersion field of each node.
# file cluster-values.yaml
apiVersion: kubeops/kubeopsctl/cluster/beta/v1
imagePullRegistry: registry.kubeops.net/kubeops/kubeops
airgap: true
clusterName: myCluster
clusterUser: root
kubernetesVersion: 1.33.5     # -> actual version
kubeVipEnabled: false
virtualIP: 10.2.10.110
firewall: nftables
pluginNetwork: calico
containerRuntime: containerd
kubeOpsRoot: /home/myuser/kubeops
serviceSubnet: 192.168.128.0/17
podSubnet: 192.168.0.0/17
debug: true
systemCpu: 250m
systemMemory: 256Mi
packageRepository: local
changeCluster: true           # -> important! Needs to be set for an upgrade
zones:
- name: zone1
  nodes:
  - name: demo-controlplane01
    iPAddress: 10.2.10.110
    type: controlplane
    kubeVersion: 1.34.1       # -> target version
  - name: demo-worker01
    iPAddress: 10.2.10.210
    type: worker
    kubeVersion: 1.34.1       # -> target version
- name: zone2
  nodes:
  - name: demo-controlplane02
    iPAddress: 10.2.10.120
    type: controlplane
    kubeVersion: 1.34.1       # ->target version
  - name: demo-worker02
    iPAddress: 10.2.10.220
    type: worker
    kubeVersion: 1.34.1       # -> target version
- name: zone3
  nodes:
  - name: demo-controlplane03
    iPAddress: 10.2.10.130
    type: controlplane
    kubeVersion: 1.34.1       # -> target version
  - name: demo-worker03
    iPAddress: 10.2.10.230
    type: worker
    kubeVersion: 1.34.1       # -> target version

2. Validate your values and upgrade the cluster

After cluster-values.yaml is updated, review all values carefully.
When you are ready, start the upgrade process:

kubeopsctl apply -f cluster-values.yaml

Example 2 - Tranche upgrade of zones to a specific version

In this example, the cluster is upgraded in tranches. The order is:

  • zone1 (because it contains the initial control plane node),
  • then zone3,
  • and finally zone2.

1. Pull required KOSI packages on your ADMIN

Pull the kubernetes v1.33.5 packages on your ADMIN machine.

kubeopsctl pull --kubernetesVersion 1.33.5

2. Adjust your cluster-values in zone1

Adjust your cluster-values.yaml according to the example below. Make sure you set:

  • The current Kubernetes version in kubernetesVersion.
  • The target Kubernetes version only for the nodes in zone1. In the snippet below, only zone1 is configured with the target version.
# file cluster-values.yaml
apiVersion: kubeops/kubeopsctl/cluster/beta/v1
imagePullRegistry: registry.kubeops.net/kubeops/kubeops
airgap: true
clusterName: myCluster
clusterUser: root
kubernetesVersion: 1.32.2     # -> actual version
kubeVipEnabled: false           
virtualIP: 10.2.10.110
firewall: nftables
pluginNetwork: calico
containerRuntime: containerd
kubeOpsRoot: /home/myuser/kubeops
serviceSubnet: 192.168.128.0/17
podSubnet: 192.168.0.0/17
debug: true
systemCpu: 250m
systemMemory: 256Mi
packageRepository: local
changeCluster: true
zones:
- name: zone1
  nodes:
  - name: demo-controlplane01
    iPAddress: 10.2.10.110
    type: controlplane
    kubeVersion: 1.33.5       # -> target version
  - name: demo-worker01
    iPAddress: 10.2.10.210
    type: worker
    kubeVersion: 1.33.5       # -> target version
- name: zone2
  nodes:
  - name: demo-controlplane02
    iPAddress: 10.2.10.120
    type: controlplane
    kubeVersion: 1.32.2       
  - name: demo-worker02
    iPAddress: 10.2.10.220
    type: worker
    kubeVersion: 1.32.2       
- name: zone3
  nodes:
  - name: demo-controlplane03
    iPAddress: 10.2.10.130
    type: controlplane
    kubeVersion: 1.32.2       
  - name: demo-worker03
    iPAddress: 10.2.10.230
    type: worker
    kubeVersion: 1.32.2

3. Validate your values and upgrade the cluster

After cluster-values.yaml is updated, review all values carefully. When you are ready, start the upgrade process:

kubeopsctl apply -f cluster-values.yaml

4. Adjust your cluster-values.yaml in zone2

Next, change the target version of zone2:

# file cluster-values.yaml
apiVersion: kubeops/kubeopsctl/cluster/beta/v1
imagePullRegistry: registry.kubeops.net/kubeops/kubeops
airgap: true
clusterName: myCluster
clusterUser: root
kubernetesVersion: 1.32.2     # -> actual version
kubeVipEnabled: false
virtualIP: 10.2.10.110
firewall: nftables
pluginNetwork: calico
containerRuntime: containerd
kubeOpsRoot: /home/myuser/kubeops
serviceSubnet: 192.168.128.0/17
podSubnet: 192.168.0.0/17
debug: true
systemCpu: 250m
systemMemory: 256Mi
packageRepository: local
changeCluster: true
zones:
- name: zone1
  nodes:
  - name: demo-controlplane01
    iPAddress: 10.2.10.110
    type: controlplane
    kubeVersion: 1.33.5       # -> target version
  - name: demo-worker01
    iPAddress: 10.2.10.210
    type: worker
    kubeVersion: 1.33.5       # -> target version
- name: zone2
  nodes:
  - name: demo-controlplane02
    iPAddress: 10.2.10.120
    type: controlplane
    kubeVersion: 1.33.5       # ->target version
  - name: demo-worker02
    iPAddress: 10.2.10.220
    type: worker
    kubeVersion: 1.33.5       # -> target version
- name: zone3
  nodes:
  - name: demo-controlplane03
    iPAddress: 10.2.10.130
    type: controlplane
    kubeVersion: 1.32.2       
  - name: demo-worker03
    iPAddress: 10.2.10.230
    type: worker
    kubeVersion: 1.32.2

5. Validate your values and upgrade the cluster

After cluster-values.yaml is updated, review all values carefully. When you are ready, start the upgrade process:

kubeopsctl apply -f cluster-values.yaml

6. Adjust your cluster-values.yaml in zone3

Finally, change the target version of zone 3.

# file cluster-values.yaml
apiVersion: kubeops/kubeopsctl/cluster/beta/v1
imagePullRegistry: registry.kubeops.net/kubeops/kubeops
airgap: true
clusterName: myCluster
clusterUser: root
kubernetesVersion: 1.32.2     # -> actual version
kubeVipEnabled: false
virtualIP: 10.2.10.110
firewall: nftables
pluginNetwork: calico
containerRuntime: containerd
kubeOpsRoot: /home/myuser/kubeops
serviceSubnet: 192.168.128.0/17
podSubnet: 192.168.0.0/17
debug: true
systemCpu: 250m
systemMemory: 256Mi
packageRepository: local
changeCluster: true
zones:
- name: zone1
  nodes:
  - name: demo-controlplane01
    iPAddress: 10.2.10.110
    type: controlplane
    kubeVersion: 1.33.5       # -> target version
  - name: demo-worker01
    iPAddress: 10.2.10.210
    type: worker
    kubeVersion: 1.33.5       # -> target version
- name: zone2
  nodes:
  - name: demo-controlplane02
    iPAddress: 10.2.10.120
    type: controlplane
    kubeVersion: 1.33.5       # ->target version
  - name: demo-worker02
    iPAddress: 10.2.10.220
    type: worker
    kubeVersion: 1.33.5       # -> target version
- name: zone3
  nodes:
  - name: demo-controlplane03
    iPAddress: 10.2.10.130
    type: controlplane
    kubeVersion: 1.33.5       # -> target version
  - name: demo-worker03
    iPAddress: 10.2.10.230
    type: worker
    kubeVersion: 1.33.5       # -> target version

7. Validate your values and upgrade the cluster

After cluster-values.yaml is updated, review all values carefully. When you are ready, start the upgrade process:

kubeopsctl apply -f cluster-values.yaml