Upgrading cluster version
I voluntarily made you install Kubernetes 1.32.0. This is because I wanted to show you how to upgrade a cluster. In this section, we will upgrade our cluster to Kubernetes 1.33.0.
Upgrade control plane
To upgrade the control plane, we will use the kubeadm upgrade command. This command will upgrade the control plane components and the kubelet.
We will first upgrade kubeadm itself.
We need to switch the Kubernetes package repository to the next minor version. To do this, we will edit the Kubernetes APT repository file.
sudo nano /etc/apt/sources.list.d/kubernetes.list
You should see a single line with the URL that contains your current Kubernetes minor version. For example, if you're using v1.32, you should see this:
deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.32/deb/ /
Change the version in the URL to the next available minor release, for example:
deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.33/deb/ /
Save the file and exit your text editor.
sudo apt-mark unhold kubeadm && \
sudo apt update && sudo apt remove -y kubeadm && sudo apt install -y kubeadm=1.33.2-1.1 && \
sudo apt-mark hold kubeadm
Now we can check if the upgrade is available.
sudo kubeadm upgrade plan
If you see the following output then you can upgrade your cluster.
[upgrade/config] Making sure the configuration is correct:
[upgrade/config] Reading configuration from the cluster...
[upgrade/config] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -oyaml'
[preflight] Running pre-flight checks.
[upgrade] Making sure the cluster is healthy:
[upgrade/health] Checking API Server health: Healthy
[upgrade/health] Checking Node health: All Nodes are healthy
[upgrade/health] Checking Static Pod manifests exists on disk: All manifests exist on disk
[upgrade/health] Checking if control plane is Static Pod-hosted or Self-Hosted: Static Pod-hosted
[upgrade/health] Checking Static Pod manifests directory is empty: The directory is not empty
[upgrade/config] The configuration was checked to be correct:
[upgrade/config] COMPONENT CURRENT AVAILABLE
[upgrade/config] API Server v1.32.6 v1.33.2
[upgrade/config] Controller Manager v1.32.6 v1.33.2
[upgrade/config] Scheduler v1.32.6 v1.33.2
[upgrade/config] Kube Proxy v1.32.6 v1.33.2
[upgrade/config] CoreDNS 1.8.0 1.8.0
[upgrade/config] Etcd 3.4.13-0 3.4.13-0
[upgrade/versions] Cluster version: v1.32.6
[upgrade/versions] kubeadm version: v1.33.2
[upgrade/versions] Latest stable version: v1.33.2
[upgrade/versions] Latest version in the v1.32 series: v1.32.6
[upgrade/versions] Latest experimental version: v1.34.0-alpha.0
Components that must be upgraded manually after you have upgraded the control plane with 'kubeadm upgrade apply':
COMPONENT CURRENT AVAILABLE
Kubelet 1 x v1.32.6 v1.33.2
Now we can upgrade the cluster.
kubeadm upgrade apply v1.33.2
If the upgrade is successful, you should see the following output.
[upgrade/successful] SUCCESS! Your cluster was upgraded to "v1.33.x". Enjoy!
[upgrade/kubelet] Now that your control plane is upgraded, please proceed with upgrading your kubelets if you haven't already done so.
Before upgrading kubelet, we need to drain the control plane node.
kubectl drain <controlplane-node-name> --ignore-daemonsets
You can now upgrade kubelet
sudo apt-mark unhold kubelet && \
sudo apt update && sudo apt remove -y kubelet && sudo apt install -y kubelet=1.33.2-1.1 && \
sudo apt-mark hold kubelet
Restart kubelet
sudo systemctl daemon-reload
sudo systemctl restart kubelet
Uncordon the control plane node
kubectl uncordon controlplane
Upgrade worker nodes
To upgrade the worker nodes the steps are similar to the control plane.
First upgrade kubeadm
Again first, we need to switch the Kubernetes package repository to the next minor version. To do this, we will edit the Kubernetes APT repository file.
sudo nano /etc/apt/sources.list.d/kubernetes.list
You should see a single line with the URL that contains your current Kubernetes minor version. For example, if you're using v1.32, you should see this:
deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.32/deb/ /
Change the version in the URL to the next available minor release, for example:
deb [signed-by=/etc/apt/keyrings/kubernetes-apt-keyring.gpg] https://pkgs.k8s.io/core:/stable:/v1.33/deb/ /
Save the file and exit your text editor.
sudo apt-mark unhold kubeadm && \
sudo apt update && sudo apt remove -y kubeadm && sudo apt install -y kubeadm=1.33.2-1.1 && \
sudo apt-mark hold kubeadm
Then upgrade the node
sudo kubeadm upgrade node
If the upgrade is successful, you should see the following output.
[upgrade/successful] SUCCESS! Your node was upgraded to "v1.33.x". Enjoy!
Before upgrading kubelet, we need to drain the worker node, so go on the controlplane and run:
kubectl drain <worker-node-name> --ignore-daemonsets
You can now upgrade kubelet
sudo apt-mark unhold kubelet && \
sudo apt update && sudo apt remove -y kubelet && sudo apt install -y kubelet=1.33.2-1.1 && \
sudo apt-mark hold kubelet
Restart kubelet
sudo systemctl daemon-reload
sudo systemctl restart kubelet
Uncordon the worker node
kubectl uncordon <worker-node-name>
Check that cluster is up
To check that the cluster is up and running you can run the following command on the control plane node:
kubectl get nodes
You should see something like this:
NAME STATUS ROLES AGE VERSION
controlplane Ready control-plane,master 10m v1.33.2
workernode Ready worker 10m v1.33.2
workernode2 Ready worker 10m v1.33.2