Updating the cluster to match with the latest CKAD exam version.
The Upgrade Path
Our cluster was originally built using Ansible (kubeadm). We will use kubeadm upgrade to upgrade it.
We will be upgrading from:
- kubeadm 1.24.6
- kubelet 1.24.6
- kubectl 1.24.6
- kubernetes-cni 1.1.1
- coredns 1.8.6
- etcd 3.5.3
- calico 3.24
- containerd 1.6.8
- Istio 1.14
to:
- kubeadm 1.25.5
- kubelet 1.25.5
- kubectl 1.25.5
- kubernetes-cni 1.1.1
- coredns 1.9.3
- etcd 3.5.6
- calico 3.25
- containerd 1.6.8
- Istio 1.16
Breaking Changes
PodSecurityPolicy has been removed in v1.25.
Note that policy/v1beta1 PodDisruptionBudget is unavailable in v1.25, use policy/v1 PodDisruptionBudget.
Backup the Cluster
Kubernetes nodes run on KVM, therefore we have taken KVM snapshosts of each virtual machine before starting the upgrade.
Upgrade Control Plane Nodes
Cluster node status before proceeding:
$ kubectl get no -o wide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME srv31 Ready control-plane 228d v1.24.6 10.11.1.31 none Rocky Linux 8.6 (Green Obsidian) 4.18.0-372.9.1.el8.x86_64 containerd://1.6.8 srv32 Ready control-plane 180d v1.24.6 10.11.1.32 none Rocky Linux 8.6 (Green Obsidian) 4.18.0-372.9.1.el8.x86_64 containerd://1.6.8 srv33 Ready control-plane 309d v1.24.6 10.11.1.33 none Rocky Linux 8.6 (Green Obsidian) 4.18.0-372.9.1.el8.x86_64 containerd://1.6.8 srv34 Ready none 309d v1.24.6 10.11.1.34 none Rocky Linux 8.6 (Green Obsidian) 4.18.0-372.9.1.el8.x86_64 containerd://1.6.8 srv35 Ready none 180d v1.24.6 10.11.1.35 none Rocky Linux 8.6 (Green Obsidian) 4.18.0-372.9.1.el8.x86_64 containerd://1.6.8 srv36 Ready none 309d v1.24.6 10.11.1.36 none Rocky Linux 8.6 (Green Obsidian) 4.18.0-372.9.1.el8.x86_64 containerd://1.6.8
Perform kubeadm upgrade
The upgrade procedure on control plane nodes should be executed one node at a time.
We will start with the control plane srv31. For the first control plane node srv31:
$ sudo yum install -y kubeadm-1.25.5-0 --disableexcludes=kubernetes $ kubeadm version
Verify the upgrade plan:
$ sudo 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' [upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace [preflight] Running pre-flight checks. [upgrade] Running cluster health checks [upgrade] Fetching available versions to upgrade to [upgrade/versions] Cluster version: v1.24.6 [upgrade/versions] kubeadm version: v1.25.5 I0118 15:13:14.565296 116046 version.go:256] remote version is much newer: v1.26.0; falling back to: stable-1.25 [upgrade/versions] Target version: v1.25.5 [upgrade/versions] Latest version in the v1.24 series: v1.24.9 Components that must be upgraded manually after you have upgraded the control plane with 'kubeadm upgrade apply': COMPONENT CURRENT TARGET kubelet 6 x v1.24.6 v1.24.9 Upgrade to the latest version in the v1.24 series: COMPONENT CURRENT TARGET kube-apiserver v1.24.6 v1.24.9 kube-controller-manager v1.24.6 v1.24.9 kube-scheduler v1.24.6 v1.24.9 kube-proxy v1.24.6 v1.24.9 CoreDNS v1.8.6 v1.9.3 etcd 3.5.3-0 3.5.6-0 You can now apply the upgrade by executing the following command: kubeadm upgrade apply v1.24.9 _____________________________________________________________________ Components that must be upgraded manually after you have upgraded the control plane with 'kubeadm upgrade apply': COMPONENT CURRENT TARGET kubelet 6 x v1.24.6 v1.25.5 Upgrade to the latest stable version: COMPONENT CURRENT TARGET kube-apiserver v1.24.6 v1.25.5 kube-controller-manager v1.24.6 v1.25.5 kube-scheduler v1.24.6 v1.25.5 kube-proxy v1.24.6 v1.25.5 CoreDNS v1.8.6 v1.9.3 etcd 3.5.3-0 3.5.6-0 You can now apply the upgrade by executing the following command: kubeadm upgrade apply v1.25.5 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 _____________________________________________________________________________________________________________________________
Upgrade the cluster:
$ sudo kubeadm upgrade apply v1.25.5
[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 "v1.25.5"
[upgrade/versions] Cluster version: v1.24.6
[upgrade/versions] kubeadm version: v1.25.5
[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/apply] Upgrading your Static Pod-hosted control plane to version "v1.25.5" (timeout: 5m0s)...
[upgrade/etcd] Upgrading to TLS for etcd
[upgrade/staticpods] Preparing for "etcd" upgrade
[upgrade/staticpods] Renewing etcd-server certificate
[upgrade/staticpods] Renewing etcd-peer certificate
[upgrade/staticpods] Renewing etcd-healthcheck-client certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/etcd.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-01-18-15-21-43/etcd.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
[apiclient] Found 3 Pods for label selector component=etcd
[upgrade/staticpods] Component "etcd" upgraded successfully!
[upgrade/etcd] Waiting for etcd to become available
[upgrade/staticpods] Writing new Static Pod manifests to "/etc/kubernetes/tmp/kubeadm-upgraded-manifests3785479248"
[upgrade/staticpods] Preparing for "kube-apiserver" upgrade
[upgrade/staticpods] Renewing apiserver certificate
[upgrade/staticpods] Renewing apiserver-kubelet-client certificate
[upgrade/staticpods] Renewing front-proxy-client certificate
[upgrade/staticpods] Renewing apiserver-etcd-client certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/kube-apiserver.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-01-18-15-21-43/kube-apiserver.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
[apiclient] Found 3 Pods for label selector component=kube-apiserver
[upgrade/staticpods] Component "kube-apiserver" upgraded successfully!
[upgrade/staticpods] Preparing for "kube-controller-manager" upgrade
[upgrade/staticpods] Renewing controller-manager.conf certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/kube-controller-manager.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-01-18-15-21-43/kube-controller-manager.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
[apiclient] Found 3 Pods for label selector component=kube-controller-manager
[upgrade/staticpods] Component "kube-controller-manager" upgraded successfully!
[upgrade/staticpods] Preparing for "kube-scheduler" upgrade
[upgrade/staticpods] Renewing scheduler.conf certificate
[upgrade/staticpods] Moved new manifest to "/etc/kubernetes/manifests/kube-scheduler.yaml" and backed up old manifest to "/etc/kubernetes/tmp/kubeadm-backup-manifests-2023-01-18-15-21-43/kube-scheduler.yaml"
[upgrade/staticpods] Waiting for the kubelet to restart the component
[upgrade/staticpods] This might take a minute or longer depending on the component/version gap (timeout 5m0s)
[apiclient] Found 3 Pods for label selector component=kube-scheduler
[upgrade/staticpods] Component "kube-scheduler" upgraded successfully!
[upgrade/postupgrade] Removing the old taint &Taint{Key:node-role.kubernetes.io/master,Value:,Effect:NoSchedule,TimeAdded:,} from all control plane Nodes. After this step only the &Taint{Key:node-role.kubernetes.io/control-plane,Value:,Effect:NoSchedule,TimeAdded:,} taint will be present on control plane Nodes.
[upload-config] Storing the configuration used in ConfigMap "kubeadm-config" in the "kube-system" Namespace
[kubelet] Creating a ConfigMap "kubelet-config" in namespace kube-system with the configuration for the kubelets in the cluster
[kubelet-start] Writing kubelet configuration to file "/var/lib/kubelet/config.yaml"
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to get nodes
[bootstrap-token] Configured RBAC rules to allow Node Bootstrap tokens to post CSRs in order for nodes to get long term certificate credentials
[bootstrap-token] Configured RBAC rules to allow the csrapprover controller automatically approve CSRs from a Node Bootstrap Token
[bootstrap-token] Configured RBAC rules to allow certificate rotation for all node client certificates in the cluster
[addons] Applied essential addon: CoreDNS
[addons] Applied essential addon: kube-proxy
[upgrade/successful] SUCCESS! Your cluster was upgraded to "v1.25.5". Enjoy!
[upgrade/kubelet] Now that your control plane is upgraded, please proceed with upgrading your kubelets if you haven't already done so.
We need to upgrade our CNI provider plugin. We are going to upgrade to Calico 3.25 which has been tested against Kubernetes version 1.26.
$ kubectl apply -f https://docs.projectcalico.org/archive/v3.25/manifests/calico.yaml poddisruptionbudget.policy/calico-kube-controllers configured serviceaccount/calico-kube-controllers unchanged serviceaccount/calico-node unchanged configmap/calico-config unchanged customresourcedefinition.apiextensions.k8s.io/bgpconfigurations.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/bgppeers.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/blockaffinities.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/caliconodestatuses.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/clusterinformations.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/felixconfigurations.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/globalnetworkpolicies.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/globalnetworksets.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/hostendpoints.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/ipamblocks.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/ipamconfigs.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/ipamhandles.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/ippools.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/ipreservations.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/kubecontrollersconfigurations.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/networkpolicies.crd.projectcalico.org configured customresourcedefinition.apiextensions.k8s.io/networksets.crd.projectcalico.org configured clusterrole.rbac.authorization.k8s.io/calico-kube-controllers unchanged clusterrole.rbac.authorization.k8s.io/calico-node configured clusterrolebinding.rbac.authorization.k8s.io/calico-kube-controllers unchanged clusterrolebinding.rbac.authorization.k8s.io/calico-node unchanged daemonset.apps/calico-node configured deployment.apps/calico-kube-controllers configured
For the other control plane nodes:
$ sudo yum install -y kubeadm-1.25.5-0 --disableexcludes=kubernetes $ kubeadm version $ sudo kubeadm config images pull $ sudo kubeadm upgrade node
According to Kubernetes documentation, calling kubeadm upgrade plan and upgrading the CNI provider plugin is no longer needed.
Drain the Nodes and Upgrade kubelet and kubectl
$ export CONTROL_PLANE="srv31"
$ kubectl drain ${CONTROL_PLANE} --ignore-daemonsets --delete-emptydir-data
$ sudo yum install -y kubelet-1.25.5-0 kubectl-1.25.5-0 --disableexcludes=kubernetes
$ sudo systemctl daemon-reload && sudo systemctl restart kubelet
$ kubectl uncordon ${CONTROL_PLANE}
Upgrade Worker Nodes
We will start with the worker node srv34.
Upgrade kubeadm:
$ sudo yum install -y kubeadm-1.25.5-0 --disableexcludes=kubernetes $ sudo kubeadm upgrade node
Drain the worker node:
$ export WORKER_NODE="srv34"
$ kubectl drain ${WORKER_NODE} --ignore-daemonsets --delete-emptydir-data
Upgrade kubelet and kubectl:
$ sudo yum install -y kubelet-1.25.5-0 kubectl-1.25.5-0 --disableexcludes=kubernetes $ sudo systemctl daemon-reload && sudo systemctl restart kubelet
Uncordon the worker node:
$ kubectl uncordon ${WORKER_NODE}
Repeat the process for worker nodes srv35 and srv36.
Verify Cluster Status
Check cluster node status:
$ kubectl get no NAME STATUS ROLES AGE VERSION srv31 Ready control-plane 228d v1.25.5 srv32 Ready control-plane 180d v1.25.5 srv33 Ready control-plane 309d v1.25.5 srv34 Ready none 309d v1.25.5 srv35 Ready none 180d v1.25.5 srv36 Ready none 309d v1.25.5
Check Calico pods:
$ kubectl -n kube-system get po -l k8s-app=calico-node NAME READY STATUS RESTARTS AGE calico-node-9mnwg 1/1 Running 0 15m calico-node-b8jk5 1/1 Running 0 19m calico-node-gzcnx 1/1 Running 0 19m calico-node-p2xt5 1/1 Running 0 18m calico-node-rd6h6 1/1 Running 0 16m calico-node-rzm6w 1/1 Running 0 17m
Update Istio
Istio Canary updates are not great because they don’t upgrade sidecars. In production we build a new Kubernetes cluster using red/black deployment and install a new version of Istio. For the purpose of the homelab environment, we will do an in-place upgrade.
Download istioctl binary:
$ curl -fsSL -o istioctl.tar.gz https://github.com/istio/istio/releases/download/1.16.1/istioctl-1.16.1-linux-amd64.tar.gz $ tar xf istioctl.tar.gz $ sudo mv istioctl /usr/local/bin/ $ sudo chown root: /usr/local/bin/istioctl
Ensure that the upgrade is compatible with our environment:
$ istioctl x precheck ✔ No issues found when checking the cluster. Istio is safe to install or upgrade!
$ istioctl version client version: 1.16.1 control plane version: 1.14.4 data plane version: 1.14.4 (15 proxies)
Generate a YAML manifest for Kubernetes:
$ git clone https://github.com/lisenet/kubernetes-homelab.git $ cd ./kubernetes-homelab/istio $ istioctl manifest generate --cluster-specific -f ./istio-operator.yml > ./istio-kubernetes.yml
Upgrade Istio. The kubectl apply command may show transient errors due to resources not being available in the cluster in the correct order. If that happens, simply run the command again.
$ kubectl apply -f ./istio-kubernetes.yml
Verify:
$ istioctl verify-install -f ./istio-kubernetes.yml
$ kubectl get po -n istio-system NAME READY STATUS RESTARTS AGE istio-ingressgateway-7f56f556b-9vjsp 1/1 Running 0 6m13s istio-ingressgateway-7f56f556b-pxmbb 1/1 Running 0 6m13s istiod-5bbc6f64bc-lcv45 1/1 Running 0 6m13s kiali-c946fb5bc-lqzgl 1/1 Running 0 17m prometheus-6d496598f9-fksjp 2/2 Running 0 17m
We should see the updated version on the control plane but a bunch of old proxies (sidecars) on the data plane:
$ istioctl version client version: 1.16.1 control plane version: 1.16.1 data plane version: 1.14.4 (2 proxies), 1.16.1 (13 proxies)
Restart all pods that have Istio sidecards running to allow them to pick up a new version of Istio. When done, we should have no old versions of proxies running:
$ istioctl version client version: 1.16.1 control plane version: 1.16.1 data plane version: 1.16.1 (15 proxies)
Note to Self
This will be the last post with regards to Kubernetes upgrades as they are all more or less the same and add little value.
References
https://kubernetes.io/docs/tasks/administer-cluster/kubeadm/kubeadm-upgrade/
https://istio.io/latest/docs/setup/upgrade/in-place/
https://github.com/istio/istio/issues/42423
Hi
Do we need to run the drain command before the ‘Kubeadm” update/upgrade apply command or just before upgrade the kubelet and kubectl.
No Worries. I have sorted out and please ignore above message.