Cluster Health Checks

Intermediate10 min

Run comprehensive health checks on your Kubernetes cluster to verify node status, component health, and system pod readiness.

Prerequisites

-kubectl configured

Steps

Check node status

Verify all nodes are in Ready state.

$ kubectl get nodes -o wide

Check component status

Verify core Kubernetes components are healthy.

$ kubectl get componentstatuses 2>/dev/null; kubectl get pods -n kube-system

componentstatuses is deprecated in newer versions. Check kube-system pods instead.

Check for pods in error states

Find pods that are not running correctly across all namespaces.

$ kubectl get pods --all-namespaces --field-selector=status.phase!=Running,status.phase!=Succeeded

Check node conditions and pressure

Look for nodes experiencing memory, disk, or PID pressure.

Verify DNS is working

Test that cluster DNS resolves service names correctly.

$ kubectl run dns-test --rm -it --restart=Never --image=busybox -- nslookup kubernetes.default

Full Script

full-script.sh

#!/bin/bash
# Cluster Health Checks
set -euo pipefail

echo "=== Node Status ==="
kubectl get nodes -o wide

echo ""
echo "=== System Pods ==="
kubectl get pods -n kube-system -o custom-columns='NAME:.metadata.name,STATUS:.status.phase,RESTARTS:.status.containerStatuses[0].restartCount,NODE:.spec.nodeName'

echo ""
echo "=== Pods Not Running ==="
kubectl get pods --all-namespaces --field-selector=status.phase!=Running,status.phase!=Succeeded 2>/dev/null || echo "All pods healthy"

echo ""
echo "=== Node Conditions ==="
kubectl get nodes -o json | jq -r '.items[] | .metadata.name + ": " + ([.status.conditions[] | select(.status=="True") | .type] | join(", "))'

echo ""
echo "=== Cluster Events (Warnings) ==="
kubectl get events --all-namespaces --field-selector type=Warning --sort-by='.lastTimestamp' 2>/dev/null | tail -10

FAQ

Discussion

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#!/bin/bash # Cluster Health Checks set -euo pipefail echo "=== Node Status ===" kubectl get nodes -o wide echo "" echo "=== System Pods ===" kubectl get pods -n kube-system -o custom-columns='NAME:.metadata.name,STATUS:.status.phase,RESTARTS:.status.containerStatuses[0].restartCount,NODE:.spec.nodeName' echo "" echo "=== Pods Not Running ===" kubectl get pods --all-namespaces --field-selector=status.phase!=Running,status.phase!=Succeeded 2>/dev/null || echo "All pods healthy" echo "" echo "=== Node Conditions ===" kubectl get nodes -o json | jq -r '.items[] | .metadata.name + ": " + ([.status.conditions[] | select(.status=="True") | .type] | join(", "))' echo "" echo "=== Cluster Events (Warnings) ===" kubectl get events --all-namespaces --field-selector type=Warning --sort-by='.lastTimestamp' 2>/dev/null | tail -10