How to Use kubectl top to Monitor Kubernetes Resources

Use kubectl top nodes to see CPU and memory usage of all nodes, and kubectl top pods to check resource usage of pods in a namespace. This command requires the Metrics Server to be installed in your cluster.

Syntax

The kubectl top command shows resource usage for nodes or pods in your Kubernetes cluster.

• kubectl top nodes: Displays CPU and memory usage for all nodes.
• kubectl top pods: Displays CPU and memory usage for pods in the current namespace.
• kubectl top pods --namespace <namespace>: Shows pod usage in a specific namespace.

bash

kubectl top nodes
kubectl top pods
kubectl top pods --namespace <namespace>

Example

This example shows how to check CPU and memory usage of nodes and pods in the default namespace.

bash

kubectl top nodes
kubectl top pods

Output

NAME           CPU(cores)   MEMORY(bytes)
node-1         250m         512Mi
node-2         180m         400Mi

NAME                           CPU(cores)   MEMORY(bytes)
nginx-pod-1                    50m          100Mi
backend-pod-1                  120m         200Mi

Common Pitfalls

Metrics Server not installed: The kubectl top command needs the Metrics Server running in your cluster. Without it, you will get an error like error: metrics API not available.

Wrong namespace: By default, kubectl top pods shows pods in the current namespace. Use --namespace to specify another.

Permissions: Make sure your user has permission to access metrics.

bash

kubectl top pods
# Error: error: metrics API not available

# Correct: Install Metrics Server
kubectl apply -f https://github.com/kubernetes-sigs/metrics-server/releases/latest/download/components.yaml

Quick Reference

Command	Description
kubectl top nodes	Show CPU and memory usage of all nodes
kubectl top pods	Show CPU and memory usage of pods in current namespace
kubectl top pods --namespace	Show pod usage in specified namespace
kubectl apply -f	Install Metrics Server if missing

Key Takeaways

kubectl top shows CPU and memory usage for nodes and pods in Kubernetes.

Metrics Server must be installed for kubectl top to work.

Use --namespace to check pods in namespaces other than the current one.

Check permissions if you get access errors.

kubectl top nodes and kubectl top pods are the main commands to remember.