𝑼𝒏𝒅𝒆𝒓𝒔𝒕𝒂𝒏𝒅𝒊𝒏𝒈 𝑲𝒖𝒃𝒆𝒓𝒏𝒆𝒕𝒆𝒔 𝑷𝒐𝒅 𝒇𝒂𝒊𝒍𝒖𝒓𝒆𝒔

Pods can have startup and runtime errors.

Startup errors include:

✅ ImagePullBackoff
✅ ImageInspectError
✅ ErrImagePull
✅ ErrImageNeverPull
✅ RegistryUnavailable
✅ InvalidImageName

Runtime errors include:

📌
✅ CrashLoopBackOff
✅ RunContainerError
✅ KillContainerError
✅ VerifyNonRootError
✅ RunInitContainerError
✅ CreatePodSandboxError
✅ ConfigPodSandboxError
✅ KillPodSandboxError
✅ SetupNetworkError
✅ TeardownNetworkError

𝑰𝒎𝒂𝒈𝒆𝑷𝒖𝒍𝒍𝑩𝒂𝒄𝒌𝑶𝒇𝒇

❗
✍ This error appears when #k8s isn’t able to retrieve the image for one of the #containers of the Pod.
There are three common culprits:
✅ The image name is invalid
✅ You specified a non-existing tag for the image.
✅ The image that you’re trying to retrieve belongs to a private registry and the cluster doesn’t have credentials to access it.
The first two cases can be solved by correcting the image name and tag.
For the last, one should add the credentials to your private registry in a Secret and reference it in the Pods

𝑹𝒖𝒏𝑪𝒐𝒏𝒕𝒂𝒊𝒏𝒆𝒓𝑬𝒓𝒓𝒐𝒓

❗
✍ The error appears when the container is unable to start before application
Common causes:
✅ Mounting a not-existent volume such as ConfigMap or Secrets
✅ Mounting a read-only volume as read-write
More detailed aspect can be found by describing the ‘failed’ pod

𝑪𝒓𝒂𝒔𝒉𝑳𝒐𝒐𝒑𝑩𝒂𝒄𝒌𝑶𝒇𝒇

❗
✍ If the container can’t start, then #Kubernetes shows the CrashLoopBackOff message as a status.
Usually, a container can’t start when:
✅ There’s an error in the application that prevents it from starting.
✅ You misconfigured the container.
✅ The Liveness probe failed too many times.

𝑷𝒐𝒅𝒔 𝒊𝒏 𝒂 𝑷𝒆𝒏𝒅𝒊𝒏𝒈 𝒔𝒕𝒂𝒕𝒆

❗
✍ Assuming that the scheduler component is running fine, here are the causes:
✅ The cluster doesn’t have enough resources such as CPU and memory to run the Pod.
✅ The current Namespace has a ResourceQuota object and creating the Pod will make the Namespace go over the quota.
✅ The Pod is bound to a Pending PersistentVolumeClaim.
The best option is to inspect the Events section in the “kubectl describe”

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Rajesh Kumar

Mentor for DevOps - DevSecOps - SRE - Cloud - Container & Micorservices at Software AG

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