TopolearnThese five commands solve most day-to-day 'why isn't it working' questions.
Your basic toolkit:
kubectl logs pod/web-abcprints a container's stdout/stderr.-ffollows,--since=10mlimits,-c namepicks a container,--previousshows the last crashed instance, the key to crash loops.kubectl logs deploy/webpicks one pod;-l app=web --prefixreads many.kubectl describe pod web-abc: state, restart count, last termination reason (e.g.OOMKilled), and events.kubectl events --for pod/web-abcorkubectl get events --sort-by=.lastTimestamp: what the scheduler, kubelet and controllers reported. Events expire after about an hour.kubectl exec -it web-abc -- shopens a shell inside the container, if the image has one.kubectl port-forward pod/web-abc 8080:80reaches a pod or Service from your laptop without exposing it.kubectl debug -it web-abc --image=busybox:1.37 --target=appadds an ephemeral container sharing the pod's namespaces: debugging tools for distroless images that have no shell.kubectl cp web-abc:/tmp/dump.txt ./dump.txtcopies files (needstarin the container).
Logs are kept only for the current and previous container on the node; for history, ship logs to a central system (Loki, Elasticsearch, CloudWatch).
Example
kubectl get pods
# web-7f9c-x2 0/1 CrashLoopBackOff 5 4m
kubectl logs web-7f9c-x2 --previous # output of the crashed run
kubectl describe pod web-7f9c-x2 | sed -n '/Last State/,/Exit Code/p'
# Last State: Terminated Reason: Error Exit Code: 1
kubectl events --for pod/web-7f9c-x2
kubectl exec -it deploy/web -- env | grep DB_
kubectl port-forward svc/web 8080:80
kubectl debug -it web-7f9c-x2 --image=busybox:1.37 --target=app -- shRemember
- logs --previous shows why the last container died
- describe and events explain scheduling and startup problems
- kubectl debug adds tools to minimal images without rebuilding
Watch out for
- Reading logs of the fresh container in a crash loop instead of --previous.