Red Hat Summit7.7. Investigating pod issues
OpenShift Container Platform leverages the Kubernetes concept of a pod, which is one or more containers deployed together on one host. A pod is the smallest compute unit that can be defined, deployed, and managed on OpenShift Container Platform 4.21.
After a pod is defined, it is assigned to run on a node until its containers exit, or until it is removed. Depending on policy and exit code, pods are either removed after exiting or retained so that their logs can be accessed.
The first thing to check when pod issues arise is the pod’s status. If an explicit pod failure has occurred, observe the pod’s error state to identify specific image, container, or pod network issues. Focus diagnostic data collection according to the error state. Review pod event messages, as well as pod and container log information. Diagnose issues dynamically by accessing running Pods on the command line, or start a debug pod with root access based on a problematic pod’s deployment configuration.
7.7.1. Understanding pod error states
Pod failures return explicit error states that can be observed in the status field in the output of oc get pods. Pod error states cover image, container, and container network related failures.
The following table provides a list of pod error states along with their descriptions.
| Pod error state | Description |
|---|---|
|
| Generic image retrieval error. |
|
| Image retrieval failed and is backed off. |
|
| The specified image name was invalid. |
|
| Image inspection did not succeed. |
|
|
|
|
| When attempting to retrieve an image from a registry, an HTTP error was encountered. |
|
| The specified container is either not present or not managed by the kubelet, within the declared pod. |
|
| Container initialization failed. |
|
| None of the pod’s containers started successfully. |
|
| None of the pod’s containers were killed successfully. |
|
| A container has terminated. The kubelet will not attempt to restart it. |
|
| A container or image attempted to run with root privileges. |
|
| Pod sandbox creation did not succeed. |
|
| Pod sandbox configuration was not obtained. |
|
| A pod sandbox did not stop successfully. |
|
| Network initialization failed. |
|
| Network termination failed. |
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