Pod is in CrashLoop which means the app dies or is unresponsive and kubernetes tries to restart it automatically.
Service degradation or unavailability. Inability to do rolling upgrades. Certain apps will not perform required tasks such as data migrations.
- Check template via
kubectl -n $NAMESPACE get pod $POD.
- Check pod events via
kubectl -n $NAMESPACE describe pod $POD.
- Check pod logs via
kubectl -n $NAMESPACE logs $POD -c $CONTAINER
- Check pod template parameters such as:
- pod priority
- resources - maybe it tries to use unavailable resource, such as GPU but there is limited number of nodes with GPU
- readiness and liveness probes may be incorrect - wrong port or command, check is failing too fast due to short timeout for response
Other things to check:
- app responding extremely slow due to resource constraints such as memory too low, not enough CPU which is required on start
- app waits for other services to start, such as database
- misconfiguration causing app crash on start
- missing files such as configmaps/secrets/volumes
- read only filesystem
- wrong user permissions in container
- lack of special container capabilities (securityContext)
- app is executed in different directory than expected (for example WORKDIR from Docerkfile is not used in OpenShift)
Talk with developers or read documentation about the app, ensure to define sane default values to start the app.
See Debugging Pods