G913 - Appendix 13 ~ Checking the K8s API endpoints status.md

G913 - Appendix 13 ~ Checking the K8s API endpoints' status

If you want or need to know the status of your Kubernetes cluster's API endpoints, you can do it with the kubectl command. The trick is about invoking directly certain URLs active in your cluster with the get action and the --raw flag.

• To check out if your K8s cluster's API endpoints are ready.

  $ kubectl get --raw='/readyz?verbose'
  [+]ping ok
  [+]log ok
  [+]etcd ok
  [+]etcd-readiness ok
  [+]informer-sync ok
  [+]poststarthook/start-kube-apiserver-admission-initializer ok
  [+]poststarthook/generic-apiserver-start-informers ok
  [+]poststarthook/priority-and-fairness-config-consumer ok
  [+]poststarthook/priority-and-fairness-filter ok
  [+]poststarthook/storage-object-count-tracker-hook ok
  [+]poststarthook/start-apiextensions-informers ok
  [+]poststarthook/start-apiextensions-controllers ok
  [+]poststarthook/crd-informer-synced ok
  [+]poststarthook/bootstrap-controller ok
  [+]poststarthook/rbac/bootstrap-roles ok
  [+]poststarthook/scheduling/bootstrap-system-priority-classes ok
  [+]poststarthook/priority-and-fairness-config-producer ok
  [+]poststarthook/start-cluster-authentication-info-controller ok
  [+]poststarthook/aggregator-reload-proxy-client-cert ok
  [+]poststarthook/start-kube-aggregator-informers ok
  [+]poststarthook/apiservice-registration-controller ok
  [+]poststarthook/apiservice-status-available-controller ok
  [+]poststarthook/kube-apiserver-autoregistration ok
  [+]autoregister-completion ok
  [+]poststarthook/apiservice-openapi-controller ok
  [+]poststarthook/apiservice-openapiv3-controller ok
  [+]shutdown ok
  readyz check passed

• To see if your K8s cluster's API endpoints are healthy.

  $ kubectl get --raw='/healthz?verbose'
  [+]ping ok
  [+]log ok
  [+]etcd ok
  [+]poststarthook/start-kube-apiserver-admission-initializer ok
  [+]poststarthook/generic-apiserver-start-informers ok
  [+]poststarthook/priority-and-fairness-config-consumer ok
  [+]poststarthook/priority-and-fairness-filter ok
  [+]poststarthook/storage-object-count-tracker-hook ok
  [+]poststarthook/start-apiextensions-informers ok
  [+]poststarthook/start-apiextensions-controllers ok
  [+]poststarthook/crd-informer-synced ok
  [+]poststarthook/bootstrap-controller ok
  [+]poststarthook/rbac/bootstrap-roles ok
  [+]poststarthook/scheduling/bootstrap-system-priority-classes ok
  [+]poststarthook/priority-and-fairness-config-producer ok
  [+]poststarthook/start-cluster-authentication-info-controller ok
  [+]poststarthook/aggregator-reload-proxy-client-cert ok
  [+]poststarthook/start-kube-aggregator-informers ok
  [+]poststarthook/apiservice-registration-controller ok
  [+]poststarthook/apiservice-status-available-controller ok
  [+]poststarthook/kube-apiserver-autoregistration ok
  [+]autoregister-completion ok
  [+]poststarthook/apiservice-openapi-controller ok
  [+]poststarthook/apiservice-openapiv3-controller ok
  healthz check passed

• To verify if the K8s cluster's API endpoints are live.

  $ kubectl get --raw='/livez?verbose'
  [+]ping ok
  [+]log ok
  [+]etcd ok
  [+]poststarthook/start-kube-apiserver-admission-initializer ok
  [+]poststarthook/generic-apiserver-start-informers ok
  [+]poststarthook/priority-and-fairness-config-consumer ok
  [+]poststarthook/priority-and-fairness-filter ok
  [+]poststarthook/storage-object-count-tracker-hook ok
  [+]poststarthook/start-apiextensions-informers ok
  [+]poststarthook/start-apiextensions-controllers ok
  [+]poststarthook/crd-informer-synced ok
  [+]poststarthook/bootstrap-controller ok
  [+]poststarthook/rbac/bootstrap-roles ok
  [+]poststarthook/scheduling/bootstrap-system-priority-classes ok
  [+]poststarthook/priority-and-fairness-config-producer ok
  [+]poststarthook/start-cluster-authentication-info-controller ok
  [+]poststarthook/aggregator-reload-proxy-client-cert ok
  [+]poststarthook/start-kube-aggregator-informers ok
  [+]poststarthook/apiservice-registration-controller ok
  [+]poststarthook/apiservice-status-available-controller ok
  [+]poststarthook/kube-apiserver-autoregistration ok
  [+]autoregister-completion ok
  [+]poststarthook/apiservice-openapi-controller ok
  [+]poststarthook/apiservice-openapiv3-controller ok
  livez check passed

Notice the following in the examples above.

• All the URLs passed to the --raw flag are relative to the connection that you've configured to your kubectl installation.
• The output from the readyz URL is slightly different from the healthz and livez ones. It prints a few more lines not shown in the other two outputs.
• Without the verbose option in the URL, you'll only get a simple undetailed result such as ok from the API.

You can also execute the same checks from within the cluster, if you set up a busybox or similar container with a curl command included in it. Then, you could invoke the API from within like below.

$ curl -k https://localhost:6443/livez?verbose

And finally, there's a deprecated but still working (up to the 1.25 version of Kubernetes at least) component status command.

$ kubectl get cs
Warning: v1 ComponentStatus is deprecated in v1.19+
NAME                 STATUS    MESSAGE   ERROR
scheduler            Healthy   ok        
controller-manager   Healthy   ok

Notice the deprecation notice in the commands output, and also that is not really that informative.

References

• Post by Bibin Wilson on LinkedIn
• Kubernetes docs, kubectl commands

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