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Pod is stuck in CrashLoopBackOff mode

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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 commands.

Option kubectl command
Debug the pod itself kubectl describe pod <pod-name>
Debug the replication controllers kubectl describe replicationcontroller <controller-name>
Read the termination message kubectl get pod <pod-name> --output=yaml
Examine the logs 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:

$ 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.

Third-party information disclaimer

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

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