# Kubernetes Cluster upgrade # Upgrading kubeadm clusters **This blog will help you to upgrade the Kubernetes cluster from v1.24.3 to v1.25.0** ## Prerequisites - Make sure the cluster health - Make sure you read the release notes carefully. [release notes ](https://github.com/kubernetes/kubernetes/tree/master/CHANGELOG) - Make sure to back up any important components. [ETCD backup and restoration](https://blog.cloudnloud.com/backup-and-restore-kubernetes-etcd) # Upgradation workflow - Upgrade a primary control plane node. - Upgrade an additional control plane node - Upgrade worker nodes # Upgrade master node 1. Upgrade kubeadm on the Control Plane node 2. Drain the Control Plane node 3. Plan the upgrade (kubeadm upgrade plan) 4. Apply the upgrade (kubeadm upgrade apply) 5. Upgrade kubelet & kubectl on the control Plane node 6. 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:~# kubeadm upgrade apply v1.25.0 [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 --ignore-daemonsets 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:~# kubectl uncordon 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:** 1. Drain the node 2. Upgrade kubeadm on the node 3. Upgrade kubelet & kubectl 4. 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:~# sudo kubeadm upgrade node [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:~# kubectl uncordon kubernet-worker 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/