Pods stuck in Terminating status

When Kubernetes Pods are stuck in a "Terminating" status, it typically means that the Pod is not able to fully shut down and be removed from the cluster. This can happen due to several reasons, and understanding these reasons can help you troubleshoot and resolve the issue.

Common Reasons for Pods Stuck in Terminating Status

1. Pending Finalizers:

   • Finalizers are pieces of code that must run before an object is deleted. If a Pod has a finalizer that isn't completing, it will prevent the Pod from being fully terminated.

2. Stuck in the Graceful Shutdown Process:

   • When a Pod is deleted, Kubernetes sends a SIGTERM signal to the containers inside the Pod, giving them time to gracefully shut down. If the containers don't terminate within the specified terminationGracePeriodSeconds, the Pod might remain stuck in "Terminating."

3. Volume Detachment Issues:

   • If the Pod is using Persistent Volumes, there might be issues detaching the volume from the Pod. This can prevent the Pod from being fully terminated.

4. Network Issues:

   • Kubernetes might be trying to clean up network resources (e.g., CNI plugins) related to the Pod. If there's a problem with the network plugin, this can cause the Pod to remain in the "Terminating" state.

5. Kubelet Issues:

   • If the kubelet on the node where the Pod is running has crashed or is unresponsive, the Pod might get stuck in the "Terminating" state.

Troubleshooting Steps

1. Check Pod Finalizers:

   • Use kubectl describe pod <pod-name> to see if the Pod has any finalizers.

   • If there's a finalizer that isn't completing, you might need to manually remove it.

   kubectl patch pod <pod-name> -p '{"metadata":{"finalizers":null}}'

2. Force Delete the Pod:

   • If the Pod is stuck and not responding to normal deletion, you can force delete it using:

   kubectl delete pod <pod-name> --grace-period=0 --force

   This command tells Kubernetes to immediately remove the Pod without waiting for graceful shutdown.

3. Check for Volume Issues:

   • If your Pod is using persistent storage, check if there are any issues with the volume attachment or detachment.

   • Use kubectl describe pod <pod-name> to look for events related to volume operations.

4. Check Node Status and Kubelet Logs:

   • Ensure the node where the Pod is running is healthy. Use kubectl get nodes and kubectl describe node <node-name> to check the node status.

   • Check the logs of the kubelet on that node to see if there are any errors or issues. The kubelet logs can usually be found in /var/log/kubelet.log.

5. Check for Network Plugin Issues:

   • If your cluster uses a CNI plugin (like Calico, Weave, etc.), check if the network plugin is functioning correctly.

   • You may need to look at the logs of the network plugin daemon set (e.g., kubectl logs -n kube-system <network-plugin-pod-name>).

6. Check the kubectl describe pod Output:

   • Use the kubectl describe pod <pod-name> command to look for clues in the Pod events and conditions.

   • This output can provide insight into why the Pod is stuck.

7. Check Controller Logs:

   • Check the logs of the controllers (like the Deployment or ReplicaSet controller) to see if there are any errors or issues preventing the Pod from terminating.

Additional Considerations

• Long Running Termination Grace Period:

  • Pods with a very long terminationGracePeriodSeconds might seem like they're stuck, but they could just be waiting to complete their graceful shutdown. You can lower this value if you suspect it's too long.

• Orphaned Resources:

  • In some cases, the cluster may have orphaned resources (like volumes or network resources) that prevent Pod termination. Investigate any associated resources and clean them up if necessary.

Conclusion

A Pod stuck in the "Terminating" state can be caused by various factors ranging from finalizers, network issues, volume detachment problems, to issues with the kubelet itself. By following the troubleshooting steps outlined above, you should be able to identify and resolve the issue, allowing the Pod to be properly terminated and removed from your cluster.

Stackoverflow link: https://stackoverflow.com/questions/35453792/pods-stuck-in-terminating-status