Runbooks

One symptom per page. Confirm it, follow the branch the output points to, and stop when the check says the incident is over.

• Service has no endpoints: the selector matches no pods, upstream returns 502 (Kubernetes)

  A Service with no endpoints has a selector that matches no pods, so its ClusterIP refuses connections and the proxy returns 502. Confirm it and fix it.

• OOMKilled (exit code 137): container exceeded its memory limit (Kubernetes)

  OOMKilled means the kernel killed a container for exceeding its memory limit. Confirm it, find the change behind it, fix and verify, with real lab output.

• ImagePullBackOff: the image could not be pulled and Kubernetes is backing off (Kubernetes)

  ImagePullBackOff means the kubelet could not pull the image and is retrying, up to 5 minutes apart. Read the event, fix the reference, verify. Lab-tested.