Pod Status Analyzer

Beginner5 min

Quickly diagnose common pod failure states including CrashLoopBackOff, ImagePullBackOff, Pending, and OOMKilled.

Prerequisites

-kubectl configured

Steps

Get pod status with restart count

View the current status and restart count for pods.

$ kubectl get pods -o custom-columns='NAME:.metadata.name,STATUS:.status.phase,RESTARTS:.status.containerStatuses[0].restartCount,REASON:.status.containerStatuses[0].state.waiting.reason'

Check why a pod is Pending

View scheduling events to understand why a pod cannot be placed on a node.

$ kubectl describe pod <pod-name> | grep -A10 'Events:'

Common causes: insufficient resources, node affinity/taint issues, or PVC binding failures.

Diagnose CrashLoopBackOff

View logs from the crashed container to understand the failure.

$ kubectl logs <pod-name> --previous

The --previous flag shows logs from the last crashed instance, which is where the error usually is.

Check for OOMKilled containers

Find containers that were killed due to exceeding their memory limit.

$ kubectl get pods -o json | jq -r '.items[] | select(.status.containerStatuses[]?.lastState.terminated.reason=="OOMKilled") | .metadata.name'

OOMKilled means the container exceeded its memory limit. Increase the limit or optimize memory usage.

Full Script

full-script.sh

#!/bin/bash
# Pod Status Analyzer
set -euo pipefail

NS=${1:-"default"}

echo "=== Pod Status Summary ($NS) ==="
kubectl get pods -n "$NS" -o custom-columns='NAME:.metadata.name,READY:.status.containerStatuses[0].ready,STATUS:.status.phase,RESTARTS:.status.containerStatuses[0].restartCount,AGE:.metadata.creationTimestamp'

echo ""
echo "=== Problem Pods ==="
echo "--- CrashLoopBackOff ---"
kubectl get pods -n "$NS" -o json | jq -r '.items[] | select(.status.containerStatuses[]?.state.waiting.reason=="CrashLoopBackOff") | .metadata.name' 2>/dev/null || echo "None"

echo "--- ImagePullBackOff ---"
kubectl get pods -n "$NS" -o json | jq -r '.items[] | select(.status.containerStatuses[]?.state.waiting.reason=="ImagePullBackOff" or .status.containerStatuses[]?.state.waiting.reason=="ErrImagePull") | .metadata.name' 2>/dev/null || echo "None"

echo "--- Pending ---"
kubectl get pods -n "$NS" --field-selector=status.phase=Pending -o name 2>/dev/null || echo "None"

echo "--- OOMKilled ---"
kubectl get pods -n "$NS" -o json | jq -r '.items[] | select(.status.containerStatuses[]?.lastState.terminated.reason=="OOMKilled") | .metadata.name' 2>/dev/null || echo "None"

FAQ

Discussion

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#!/bin/bash # Pod Status Analyzer set -euo pipefail NS=${1:-"default"} echo "=== Pod Status Summary ($NS) ===" kubectl get pods -n "$NS" -o custom-columns='NAME:.metadata.name,READY:.status.containerStatuses[0].ready,STATUS:.status.phase,RESTARTS:.status.containerStatuses[0].restartCount,AGE:.metadata.creationTimestamp' echo "" echo "=== Problem Pods ===" echo "--- CrashLoopBackOff ---" kubectl get pods -n "$NS" -o json | jq -r '.items[] | select(.status.containerStatuses[]?.state.waiting.reason=="CrashLoopBackOff") | .metadata.name' 2>/dev/null || echo "None" echo "--- ImagePullBackOff ---" kubectl get pods -n "$NS" -o json | jq -r '.items[] | select(.status.containerStatuses[]?.state.waiting.reason=="ImagePullBackOff" or .status.containerStatuses[]?.state.waiting.reason=="ErrImagePull") | .metadata.name' 2>/dev/null || echo "None" echo "--- Pending ---" kubectl get pods -n "$NS" --field-selector=status.phase=Pending -o name 2>/dev/null || echo "None" echo "--- OOMKilled ---" kubectl get pods -n "$NS" -o json | jq -r '.items[] | select(.status.containerStatuses[]?.lastState.terminated.reason=="OOMKilled") | .metadata.name' 2>/dev/null || echo "None"