kubectl is Kubernetes command-line tool that allows you to run commands against Kubernetes clusters.
The kubectl command line tool lets you control Kubernetes clusters. For configuration, kubectl looks for a file named config in the $HOME/.kube directory. You can specify other kubeconfig files by setting the KUBECONFIG environment variable or by setting the --kubeconfig flag.
example:
kubectl command to pass kubeconfig as commandline argument & fetch client & server version => kubectl --kubeconfig=<kubeconfig_file_path> version
Cluster Management:
Display the Kubernetes version running on both the client and server => kubectl version
Display endpoint information about the master and services in the cluster => kubectl cluster-info
Get the configuration of the cluster => kubectl config view
List the API resources that are available => kubectl api-resources
List all everything(running resources in all namespaces) => kubectl get all -A
Nodes(no):
Update the taints on one or more nodes => kubectl taint node <node_name>
List one or more nodes => kubectl get node
Describe one or more nodes => kubectl get node
Show node labels => kubectl get nodes --show-labels
Add or update the labels of one or more nodes => kubectl label node <node-name> <key>=<value>
Display Resource usage (CPU/Memory/Storage) for nodes => kubectl top node
Delete a node or multiple nodes => kubectl delete node <node_name>
Resource allocation per node => kubectl describe nodes | grep Allocated -A 5
GPU Resource available/used per node =>
kubectl describe nodes | tr -d '\000' | sed -n -e '/^Name/,/Roles/p' -e '/^Capacity/,/Allocatable/p' -e '/^Allocated resources/,/Events/p' | grep -e Name -e nvidia.com | perl -pe 's/\n//' | perl -pe 's/Name:/\n/g' | sed 's/nvidia.com\/gpu:\?//g' | sed '1s/^/Node Available(GPUs) Used(GPUs)/' | sed 's/$/ 0 0 0/' | awk '{print $1, $2, $3}' | column -t
Pods running on a node => kubectl get pods -o wide | grep <node_name>
Annotate a node => kubectl annotate node <node_name>
Mark a node as unschedulable => kubectl cordon node <node_name>
Mark node as schedulable => kubectl uncordon node <node_name>
Pods(po):
List one or more pods => kubectl get pod
List one or more pods in all namespaces => kubectl get pod -A
List one or more pods in wide format => kubectl get pod -o wide
List one or more pods yaml spec => kubectl get pod -o yaml
List one or more pods of a specific namespace => kubectl get pod -n <namespace_name>
Delete a pod => kubectl delete pod <pod_name>
Display the detailed state of a pods => kubectl describe pod <pod_name>
Create a pod => kubectl create pod <pod_name>
Execute a command against a container in a pod => kubectl exec <pod_name> -c <container_name> <command>
Get interactive shell on a a single-container pod => kubectl exec -it <pod_name> /bin/sh
Display Resource usage (CPU/Memory/Storage) for pods => kubectl top pod
Add or update the annotations of a pod => kubectl annotate pod <pod_name> <annotation>
Add or update the label of a pod => kubectl label pod <pod_name>
Services(svc):
List one or more services => kubectl get services
List one or more services in all namespaces => kubectl get svc -A
Display the detailed state of a service => kubectl describe services
Expose a replication controller, service, deployment or pod as a new Kubernetes service => kubectl expose deployment <deployment_name>
Edit and update the definition of one or more services => kubectl edit services
Watch:
To monitor progress, use the kubectl get service command with the --watch argument.
example:
kubectl get service azure-vote-front --watch
Secrets:
Create a secret => kubectl create secret
List secrets => kubectl get secrets
List details about secrets => kubectl describe secrets
Delete a secret => kubectl delete secret <secret_name>
Deployments(deploy):
List one or more deployments in default namespace => kubectl get deployment
List one or more deployments in all namespaces => kubectl get deployment -A
Display the detailed state of one or more deployments => kubectl describe deployment <deployment_name>
Edit and update the definition of one or more deployment on the server => kubectl edit deployment <deployment_name>
Create one a new deployment => kubectl create deployment <deployment_name>
Delete deployments => kubectl delete deployment <deployment_name>
Logs:
Print the logs for a pod => kubectl logs <pod_name>
Print the logs for a pod and follow new logs => kubectl logs -f <pod_name>
Print the logs for a container in a pod => kubectl logs -c <container_name> <pod_name>
Output the logs for a pod into a file named ‘pod.log’ => kubectl logs <pod_name> pod.log
View the logs for a previously failed pod => kubectl logs --previous <pod_name>
Print the logs for the last hour for a pod => kubectl logs --since=1h <pod_name>
Get the most recent 20 lines of logs => kubectl logs --tail=20 <pod_name>
Get logs from a service and optionally select which container => kubectl logs -f <service_name> [-c <$container>]
Events(ev):
List recent events for all resources in the system => kubectl get events
List Warnings only => kubectl get events --field-selector type=Warning
List events but exclude Pod events => kubectl get events --field-selector involvedObject.kind!=Pod
Manifest Files:
Apply a configuration to an object by filename or stdin. Overrides the existing configuration => kubectl apply -f manifest_file.yaml
Create objects => kubectl create -f manifest_file.yaml
Create objects in all manifest files in a directory => kubectl create -f ./dir
Create objects from a URL => kubectl create -f ‘url’
Delete an object => kubectl delete -f manifest_file.yaml
ref:
Kubectl overview - https://kubernetes.io/docs/reference/kubectl/overview/
Install kubectl - https://kubernetes.io/docs/tasks/tools/install-kubectl/
kubectl cheat sheet -
https://kubernetes.io/docs/reference/kubectl/cheatsheet/
https://www.bluematador.com/learn/kubectl-cheatsheet
https://unofficial-kubernetes.readthedocs.io/en/latest/user-guide/kubectl-cheatsheet/
