K8s Troubleshooting — Pending Pods

K8s Troubleshooting handbook

Note, full K8s troubleshooting mind map is available at: “K8s Troubleshooting MindMap”

What is “Pending Pods” Error?

In K8s, when a pod is in a “Pending” state, it means that the pod hasn’t been successfully scheduled and started on a worker node. There can be various reasons why a pod remains in this state, and it’s often crucial to diagnose the root cause to ensure proper cluster operation.

For example, the error message may look like:

Name:         my-pending-pod
Namespace:    default
...
Status:       Pending
...
Events:
  Type     Reason            Age                From               Message
  ----     ------            ----               ----               -------
  Warning  FailedScheduling  30s (x8 over 3m)   default-scheduler  0/3 nodes are available: 1 Insufficient cpu, 2 node(s) had taint {key=value:NoSchedule}, that the pod didn't tolerate.

In this example, the error message indicates that the pod couldn’t be scheduled because:

1. One node doesn’t have enough CPU.
2. Two nodes have a taint that the pod doesn’t tolerate.

To solve such issues, you may need to adjust pod specifications, node taints/tolerations…