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DevOps Insights

Start from the error, not the table of contents

Named failure states with every cause we can document, a command that confirms or rules out each one, and how to check the fix held. Written by someone who runs this in production — including the parts that break at 3am.

Known error states resolve instantly. Anything else searches the whole site.

Symptom

ImagePullBackOff

5 documented causes

  1. The image name or tag is wrong

    kubectl describe pod <pod> | grep -A5 Events
  2. Missing or wrong registry credentials

    kubectl get pod <pod> -o jsonpath='{.spec.imagePullSecrets}'
  3. The registry is implied rather than stated

    kubectl get pod <pod> -o jsonpath='{.spec.containers[*].image}'
  4. The node cannot reach the registry

    kubectl describe pod <pod> | grep -i -E 'timeout|no such host|connection refused|i/o timeout'
Read from this site’s own catalogue, not written for this panel. Ordered by how often each cause turns out to be the one — the commands decide it, because nothing here can see your cluster.

How every troubleshooting page works

See it on CrashLoopBackOff →

Not a list of articles about Kubernetes. A path from the error you are looking at to a cause you have confirmed — because nothing here can see your cluster, so nothing here asks you to take its word for it.

  1. 01 · SymptomThe string on your screen.CrashLoopBackOff
  2. 02 · EvidenceOne command that shows where you are.kubectl describe pod
  3. 03 · Cause spaceEvery cause it could be, ranked by how often it is the answer.6 documented causes
  4. 04 · ConfirmA command per cause that proves or kills it.Last State: OOMKilled
  5. 05 · FixWhat to change, once you know which one it is.Raise the memory limit
  6. 06 · VerifyHow to know it actually worked.Restart count stops rising

What is actually in here

Small on purpose. Every failure state here lists every cause we could document and source, which is only possible for problems that have a finite cause set — so the catalogue grows when there is something complete to add, not to fill a page.