kubectl top is a command that allows you to get resource usage information for Kubernetes objects such as pods, nodes, and containers. With this command, you can monitor and troubleshoot the resource usage of your Kubernetes cluster.
In this blog post, we will focus on kubectl top commands for pods and nodes, and some examples of how to use these commands to sort the pods by CPU/memory usage.
kubectl top pod
The kubectl top pod command allows you to get CPU and memory usage information for pods running in your cluster. To use this command, simply run:
This will show the CPU and memory usage for all pods in the default namespace. If you want to view the usage for a specific namespace, you can use the -n option:
kubectl top pod -n <namespace>
To sort the pods by CPU or memory usage, you can use the –sort-by option. For example, to sort the pods by CPU usage, run:
kubectl top pod --sort-by cpu
This will show the pods sorted by CPU usage in descending order. To sort the pods by memory usage, run:
kubectl top pod --sort-by memory
kubectl top node
The kubectl top node command allows you to get CPU and memory usage information for nodes in your cluster. To use this command, simply run:
This will show the CPU and memory usage for all nodes in your cluster. To view the usage for a specific node, you can use the -l option:
kubectl top node -l <node-name>
To sort the nodes by CPU or memory usage, you can use the –sort-by option. For example, to sort the nodes by CPU usage, run:
kubectl top node --sort-by cpu
This will show the nodes sorted by CPU usage in descending order. To sort the nodes by memory usage, run:
kubectl top node --sort-by memory
Other common useful features
Here are some other common features that you may find useful when using kubectl top:
To view the resource usage for a specific container in a pod, you can use the -c option followed by the container name:
kubectl top pod <pod-name> -c <container-name>
To view the resource usage for all containers in a pod, you can use the –containers option:
kubectl top pod <pod-name> --containers
To view the resource usage for a specific node over time, you can use the -w option followed by the node name:
kubectl top node -w -l <node-name>
This will show the resource usage for the node in real-time.
To view the top processes consuming CPU in a container, you can use the top command:
kubectl exec <pod-name> -c <container-name> -- top
This will show the top processes consuming CPU in the container.
Conclusion
In conclusion, kubectl top is a powerful command that allows you to monitor the resource usage of your Kubernetes cluster. With the ability to sort by CPU and memory usage, as well as other useful features, this command can help you troubleshoot performance issues and optimize resource allocation.