This guide explores methods for troubleshooting control plane failures in Kubernetes clusters, including node health checks and component status verification.
In this guide, we explore effective methods for troubleshooting control plane failures in your Kubernetes cluster. The process begins with checking the health of the nodes, followed by verifying the status of control plane components—whether they are deployed as pods or native services—and finally, reviewing detailed logs to identify any issues.
Control plane components can either be deployed as pods (common with kubeadm setups) or as native system services. Depending on your configuration, follow the appropriate checks.
If your control plane components are deployed as pods in the kube-system namespace, ensure each pod is healthy. For configurations using native services, verify that the Kubernetes API server, controller manager, scheduler, and the kube-proxy service (on worker nodes) are running properly.
For systems using native services, inspect the API server status with:
service kube-apiserver status● kube-apiserver.service - Kubernetes API Server Loaded: loaded (/etc/systemd/system/kube-apiserver.service; enabled; vendor preset: enabled) Active: active (running) since Wed 2019-03-20 07:57:25 UTC; 1 weeks 1 days ago Docs: https://github.com/kubernetes/kubernetes Main PID: 15767 (kube-apiserver) Tasks: 13 (limit: 2362)
If the control plane components are deployed as pods, fetch the logs for the API server from the kube-system namespace:
kubectl logs kube-apiserver-master -n kube-system
An example excerpt from the logs might appear as follows:
I0401 13:45:38.190735 1 server.go:703] external host was not specified, using 172.17.0.117I0401 13:45:38.194290 1 server.go:145] Version: v1.11.3I0401 13:45:38.819075 1 plugins.go:158] Loaded 8 mutating admission controller(s) successfully in the following order:NamespaceLifecycle,LimitRanger,ServiceAccount,NodeRestriction,Priority,DefaultTolerationSeconds,DefaultStorageClass,MutatingAdmissionWebhook....W0401 13:45:41.381736 1 genericapiserver.go:319] Skipping API scheduling.k8s.io/v1alpha1 because it has no resources.
For further details and advanced troubleshooting techniques, refer to the official Kubernetes Documentation.By following these steps, you can systematically diagnose and address control plane issues within your Kubernetes cluster, ensuring a stable and resilient environment.
