This article covers ways to tackle and avoid the CrashLoopBackOff error in Kubernetes. In fact, CrashLoopBackOff is a status message that indicates one of your pods is in a constant state of flux— one or more containers are failing and restarting repeatedly. This typically happens because each pod inherits a default restartPolicy of Always upon creation.
Examples of why a pod would fall into a CrashLoopBackOff state include:
- Errors when deploying Kubernetes.
- Missing dependencies.
- Changes caused by recent updates.
Activity process common to the discovery-to-fix a CrashLoopBackOff message:
- The discovery process: This includes learning that one or more pods are in the restart loop and witnessing the apps contained therein either offline or just performing below optimal levels.
- Information gathering: Immediately after the first step, most engineers will run a kubectl get pods command to learn a little more about the source of the failure. Common output from this is a list of all pods along with their current state
- Drill down on specific pod(s): Once you know which pods are in the CrashLoopBackOff state, your next task is targeting each of them to get more details about their setup. For this, you can run the kubectl describe pod [variable] command with the name of your target pod as the command variable.
- Once you've reached this point, several keywords should stick out. Focusing on these should make light work of decoding the list of variables around your pod.