Merge branch 'main' into live

Author: Deland-Han

support/azure/azure-kubernetes/pod-stuck-crashloopbackoff-mode.md

@@ -1,22 +1,74 @@
 ---
 title: Pod is stuck in CrashLoopBackOff mode
 description: Troubleshoot a scenario in which a pod is stuck in CrashLoopBackOff mode on an Azure Kubernetes Service (AKS) cluster.
-ms.date: 07/08/2022
+ms.date: 09/07/2023
+author: VikasPullagura-MSFT
+ms.author: vipullag
 editor: v-jsitser
-ms.reviewer: chiragpa, nickoman, v-leedennis
+ms.reviewer: chiragpa, nickoman, cssakscic, v-leedennis
 ms.service: azure-kubernetes-service
 ms.subservice: common-issues
-keywords:
-#Customer intent: As an Azure Kubernetes user, I want to troubleshoot why my pod is stuck in CrashLoopBackOff mode so that I can continue to use applications that are deployed to my Azure Kubernetes Service (AKS) cluster successfully.
 ---
 # Pod is stuck in CrashLoopBackOff mode
 
-There are several possible reasons why your pod is stuck in `CrashLoopBackOff` mode. Consider the following options and their associated [kubectl](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands) commands.
+If a pod has a `CrashLoopBackOff` status, then the pod probably failed or exited unexpectedly, and the log contains an exit code that isn't zero. There are several possible reasons why your pod is stuck in `CrashLoopBackOff` mode. Consider the following options and their associated [kubectl](https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands) commands.
 
-| Option                                                                                                               | kubectl command                   |
-|----------------------------------------------------------------------------------------------------------------------|-----------------------------------|
+| Option | kubectl command |
+|--|--|
 | [Debug the pod](https://kubernetes.io/docs/tasks/debug-application-cluster/debug-application/#debugging-pods) itself | `kubectl describe pod <pod-name>` |
-| Examine the logs                                                                                                     | `kubectl logs <pod-name>`         |
+| [Debug the replication controllers](https://kubernetes.io/docs/tasks/debug/debug-application/debug-pods/#debugging-replication-controllers) | `kubectl describe replicationcontroller <controller-name>` |
+| [Read the termination message](https://kubernetes.io/docs/tasks/debug/debug-application/determine-reason-pod-failure/#writing-and-reading-a-termination-message) | `kubectl get pod <pod-name> --output=yaml` |
+| [Examine the logs](https://kubernetes.io/docs/concepts/cluster-administration/logging/) | `kubectl logs <pod-name>` |
+
+> [!NOTE]  
+> A pod can also have a `CrashLoopBackOff` status if it has finished deployment, but it's configured to keep restarting even if the exit code is zero. For example, if you deploy a busybox image without specifying any arguments, the image starts, runs, finishes, and then restarts in a loop:
+>
+> ```console
+> $ kubectl run nginx --image nginx
+> pod/nginx created
+> 
+> $ kubectl run busybox --image busybox
+> pod/busybox created
+> 
+> $ kubectl get pods --watch
+> NAME     READY  STATUS             RESTARTS  AGE
+> busybox  0/1    ContainerCreating  0         3s
+> nginx    1/1    Running            0         11s
+> busybox  0/1    Completed          0         3s
+> busybox  0/1    Completed          1         4s
+> busybox  0/1    CrashLoopBackOff   1         5s
+> 
+> $ kubectl describe pod busybox
+> Name:         busybox
+> Namespace:    default
+> Priority:     0
+> Node:         aks-nodepool<number>-<resource-group-hash-number>-vmss<number>/<ip-address-1>
+> Start Time:   Wed, 16 Aug 2023 09:56:19 +0000
+> Labels:       run=busybox
+> Annotations:  <none>
+> Status:       Running
+> IP:           <ip-address-2>
+> IPs:
+>   IP:  <ip-address-2>
+> Containers:
+>   busybox:
+>     Container ID:   containerd://<64-digit-hexadecimal-value-1>
+>     Image:          busybox
+>     Image ID:       docker.io/library/busybox@sha256:<64-digit-hexadecimal-value-2>
+>     Port:           <none>
+>     Host Port:      <none>
+>     State:          Waiting
+>       Reason:       CrashLoopBackOff
+>     Last State:     Terminated
+>       Reason:       Completed
+>       Exit Code:    0
+>       Started:      Wed, 16 Aug 2023 09:56:37 +0000
+>       Finished:     Wed, 16 Aug 2023 09:56:37 +0000
+>     Ready:          False
+>     Restart Count:  2
+> ```
+
+If you don't recognize the issue after you create more pods on the node, then run a pod on a single node to determine how many resources the pod actually uses.
 
 [!INCLUDE [Third-party disclaimer](../../includes/third-party-disclaimer.md)]