Upgrading kubeadm clusters
This blog will help you to upgrade the Kubernetes cluster from v1.24.3 to v1.25.0
Prerequisites
Upgradation workflow
- Upgrade a primary control plane node.
- Upgrade an additional control plane node
- Upgrade worker nodes
Upgrade master node
- Upgrade kubeadm on the Control Plane node
- Drain the Control Plane node
- Plan the upgrade (kubeadm upgrade plan)
- Apply the upgrade (kubeadm upgrade apply)
- Upgrade kubelet & kubectl on the control Plane node
- Uncordon the Control Plane node
Update the package manager
apt update
apt-cache madison kubeadm
Find the Latest version
root@Kubernet-Master:~# apt-cache madison kubeadm
kubeadm | 1.25.0-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
kubeadm | 1.24.4-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
kubeadm | 1.24.3-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
kubeadm | 1.24.2-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
kubeadm | 1.24.1-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
kubeadm | 1.24.0-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
kubeadm | 1.23.10-00 | http://apt.kubernetes.io kubernetes-xenial/main amd64 Packages
Check the Kubeadm current version
root@Kubernet-Master:~# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"24", GitVersion:"v1.24.3", GitCommit:"aef86a93758dc3cb2c658dd9657ab4ad4afc21cb", GitTreeState:"clean", BuildDate:"2022-07-13T14:29:09Z", GoVersion:"go1.18.3", Compiler:"gc", Platform:"linux/amd64"}
Kubernetes node status and version
root@Kubernet-Master:~# kubectl get node
NAME STATUS ROLES AGE VERSION
kubernet-master Ready control-plane 36d v1.24.3
kubernet-worker Ready worker 36d v1.24.3
kubernet-worker02 Ready worker02 20d v1.24.3
Upgrade the kubeadm
apt-mark unhold kubeadm && apt-get update && apt-get install -y kubeadm=1.25.0-00 && apt-mark hold kubeadm
Verify the latest version
root@Kubernet-Master:~# kubeadm version
kubeadm version: &version.Info{Major:"1", Minor:"25", GitVersion:"v1.25.0", GitCommit:"a866cbe2e5bbaa01cfd5e969aa3e033f3282a8a2", GitTreeState:"clean", BuildDate:"2022-08-23T17:43:25Z", GoVersion:"go1.19", Compiler:"gc", Platform:"linux/amd64"}
Verify the upgrade plan
root@Kubernet-Master:~# kubeadm upgrade plan
[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 -o yaml'
[preflight] Running pre-flight checks.
[upgrade] Running cluster health checks
Components that must be upgraded manually after you have upgraded the control plane with 'kubeadm upgrade apply':
COMPONENT CURRENT TARGET
kubelet 3 x v1.24.3 v1.25.0
Upgrade to the latest stable version:
COMPONENT CURRENT TARGET
kube-apiserver v1.24.3 v1.25.0
kube-controller-manager v1.24.3 v1.25.0
kube-scheduler v1.24.3 v1.25.0
kube-proxy v1.24.3 v1.25.0
CoreDNS v1.8.6 v1.9.3
etcd 3.5.3-0 3.5.4-0
You can now apply the upgrade by executing the following command:
kubeadm upgrade apply v1.25.0
_____________________________________________________________________
The table below shows the current state of component configs as understood by this version of kubeadm.
Configs that have a "yes" mark in the "MANUAL UPGRADE REQUIRED" column require manual config upgrade or
resetting to kubeadm defaults before a successful upgrade can be performed. The version to manually
upgrade to is denoted in the "PREFERRED VERSION" column.
API GROUP CURRENT VERSION PREFERRED VERSION MANUAL UPGRADE REQUIRED
kubeproxy.config.k8s.io v1alpha1 v1alpha1 no
kubelet.config.k8s.io v1beta1 v1beta1 no
_____________________________________________________________________
Choose the Version and run the upgrade command
root@Kubernet-Master:~
[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 -o yaml'
[preflight] Running pre-flight checks.
[upgrade] Running cluster health checks
[upgrade/version] You have chosen to change the cluster version to "v1.25.0"
[upgrade/versions] Cluster version: v1.24.3
[upgrade/versions] kubeadm version: v1.25.0
[upgrade] Are you sure you want to proceed? [y/N]: y
[upgrade/prepull] Pulling images required for setting up a Kubernetes cluster
[upgrade/prepull] This might take a minute or two, depending on the speed of your internet connection
[upgrade/prepull] You can also perform this action in beforehand using 'kubeadm config images pull'
[upgrade/successful] SUCCESS! Your cluster was upgraded to "v1.25.0". Enjoy!
[upgrade/kubelet] Now that your control plane is upgraded, please proceed with upgrading your kubelets if you haven't already done so.
Drain the master node
root@Kubernet-Master:~# kubectl drain kubernet-master
node/kubernet-master cordoned
WARNING: ignoring DaemonSet-managed Pods: kube-system/calico-node-5cptw, kube-system/kube-proxy-gfhms
node/kubernet-master drained
Verifying the drain status
root@Kubernet-Master:~# kubectl get node
NAME STATUS ROLES AGE VERSION
kubernet-master Ready,SchedulingDisabled control-plane 37d v1.24.3
kubernet-worker Ready worker 37d v1.24.3
kubernet-worker02 Ready worker02 20d v1.24.3
Upgrade kubelet and kubectl
root@Kubernet-Master:~# apt-mark unhold kubelet kubectl && \
> apt-get update && apt-get install -y kubelet=1.25.0-00 kubectl=1.25.0-00 && \
> apt-mark hold kubelet kubectl
kubelet was already not hold.
kubectl was already not hold.
Get:1 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB]
Hit:3 http://ci.archive.ubuntu.com/ubuntu focal InRelease
Get:4 http://ci.archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB]
Get:5 http://security.ubuntu.com/ubuntu focal-security/main amd64 DEP-11 Metadata [40.8 kB]
Get:1 https://packages.cloud.google.com/apt kubernetes-xenial/main amd64 kubectl amd64 1.25.0-00 [9,500 kB]
Get:2 https://packages.cloud.google.com/apt kubernetes-xenial/main amd64 kubelet amd64 1.25.0-00 [19.5 MB]
Fetched 29.0 MB in 9s (3,311 kB/s)
(Reading database ... 184662 files and directories currently installed.)
Preparing to unpack .../kubectl_1.25.0-00_amd64.deb ...
Unpacking kubectl (1.25.0-00) over (1.24.3-00) ...
Preparing to unpack .../kubelet_1.25.0-00_amd64.deb ...
Unpacking kubelet (1.25.0-00) over (1.24.3-00) ...
Setting up kubectl (1.25.0-00) ...
Setting up kubelet (1.25.0-00) ...
kubelet set on hold.
kubectl set on hold.
Restart the kubelet:
sudo systemctl daemon-reload
sudo systemctl restart kubelet
Uncordon the node
root@Kubernet-Master:~
node/kubernet-master uncordoned
Verifying the master node status and check the version
root@Kubernet-Master:~# kubectl get node
NAME STATUS ROLES AGE VERSION
kubernet-master Ready control-plane 37d v1.25.0
kubernet-worker Ready worker 37d v1.24.3
kubernet-worker02 Ready worker02 20d v1.24.3
root@Kubernet-Master:~#
Upgrading the worker nodes
The upgrade procedure on worker nodes should be run one node at a time or a few nodes at a time, without compromising the minimum required capacity for running your workloads.
Upgrading the worker nodes consist of the following steps:
- Drain the node
- Upgrade kubeadm on the node
- Upgrade kubelet & kubectl
- Uncordon the node
ssh into the worker node
Upgrade kubeadm
apt-mark unhold kubeadm && \
apt-get update && apt-get install -y kubeadm=1.25.0-00 && \
apt-mark hold kubeadm
Kubeadm upgrade
root@Kubernet-Worker:~
[upgrade] Reading configuration from the cluster...
[upgrade] FYI: You can look at this config file with 'kubectl -n kube-system get cm kubeadm-config -o yaml'
[preflight] Running pre-flight checks
[preflight] Skipping prepull. Not a control plane node.
[upgrade] Skipping phase. Not a control plane node.
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[upgrade] The configuration for this node was successfully updated!
[upgrade] Now you should go ahead and upgrade the kubelet package using your package manager.
Drain the worker node
kubectl drain kuernet-worker --ignore-daemonsets
Upgrade kubelet and kubectl
apt-mark unhold kubelet kubectl && \
apt-get update && apt-get install -y kubelet=1.25.0-00 kubectl=1.25.0-00 && \
apt-mark hold kubelet kubectl
Restart the kubelet
sudo systemctl daemon-reload
sudo systemctl restart kubelet
Uncordon the node
root@Kubernet-Master:~
node/kubernet-worker uncordoned
Verify the status of the cluster
root@Kubernet-Master:~# kubectl get node
NAME STATUS ROLES AGE VERSION
kubernet-master Ready control-plane 37d v1.25.0
kubernet-worker Ready worker 37d v1.25.0
kubernet-worker02 Ready worker02 20d v1.24.3
For the other worker node upgrade follow the same steps:
root@Kubernet-Master:~# kubectl get node
NAME STATUS ROLES AGE VERSION
kubernet-master Ready control-plane 37d v1.25.0
kubernet-worker Ready worker 37d v1.25.0
kubernet-worker02 Ready worker02 20d v1.25.0
Hope you got an idea of how to upgrade the kubernetes cluster
Thank you!
Related/References
https://blog.cloudnloud.com/series/kubernetes-deep-dive
https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/
