{"id":67,"date":"2024-11-03T00:56:03","date_gmt":"2024-11-03T00:56:03","guid":{"rendered":"https:\/\/firewallsudhan.in\/?p=67"},"modified":"2024-11-03T00:56:06","modified_gmt":"2024-11-03T00:56:06","slug":"kubernetes-commands","status":"publish","type":"post","link":"https:\/\/firewallsudhan.in\/index.php\/2024\/11\/03\/kubernetes-commands\/","title":{"rendered":"Kubernetes – Commands"},"content":{"rendered":"\n

Getting Started<\/p>\n\n\n\n

Command<\/td>Explanation<\/td><\/tr>
minikube start –driver=virtualbox<\/td>If you are not using Docker Desktop, minikube can help setup a cluster with Virtualbox as driver<\/td><\/tr>
kubectl run hello-minikube –image=nginx<\/td>Runs a Pod named hello-minikube<\/code> with a nginx image.<\/td><\/tr>
kubectl cluster-info<\/td>Displays cluster information, including API server and core services URLs.<\/td><\/tr>
kubectl run nginx –image=nginx –dry-run=client -o yaml > nginx.yaml<\/td>Generates a YAML configuration for a pad using nginx image without actually creating it in the cluster and saves the generated yaml file to nginx.yaml. –dry-run=client option simulates the command locally without sending it to the API Server. Useful for testing and generating configuration files.<\/td><\/tr>
kubectl run nginx –image nginx -n mynamespace<\/td>Runs a pod named ‘nginx’ in the ‘mynamespace’ namespace.<\/td><\/tr>
kubectl get events -o wide<\/td>Lists events across the cluster with additional details.<\/td><\/tr>
kubectl get all<\/td>Lists all resources in the current namespace<\/td><\/tr>
kubectl get all -A<\/td>Lists all resources across all namespaces.<\/td><\/tr>
kubectl get all –selector app=web-app<\/td>Lists all resources labeled with app=web-app<\/code><\/td><\/tr>
kubectl port-forward –help<\/td>Displays help for the port-forward<\/code> command.<\/td><\/tr>
kubectl port-forward pod\/mypod 8888:5000<\/td>Forwards local port 8888 to port 5000 on mypod<\/code><\/td><\/tr>
kubectl exec -it ubuntu –bash<\/td>Opens an interactive Bash session in the ubuntu<\/code> Pod<\/td><\/tr>
kubectl exec -it mypod -c sidecar –touch \/tmp\/crash<\/td>Creates a file \/tmp\/crash<\/code> in the sidecar<\/code> container of mypod<\/code><\/td><\/tr>
kubectl explain pod.spec.restartPolicy<\/td>Provides documentation for the restartPolicy<\/code> field in the Pod spec<\/td><\/tr>
kubectl api-resources<\/td>To find out shortnames, namespaced or not and kind of resources. Retrieve list of all available API groups in a k8 cluster.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Nodes & Node Management<\/p>\n\n\n\n

Command<\/td>Explanation<\/td><\/tr>
kubectl get nodes<\/td>Lists all nodes in current namespace<\/td><\/tr>
kubectl get nodes -o wide<\/td>Lists nodes with additional details like IP Addresses and roles<\/td><\/tr>
kubectl get node <NODE_NAME> –show-labels<\/td>View labels for a specific node<\/td><\/tr>
kubectl drain <NODE_NAME> –delete-emptydir-data –ignore-daemonsets<\/td>Prepares a node for maintenance by evicting pods<\/td><\/tr>
kubectl cordon control-plane<\/td>Marks the control-plane node as unschedulable<\/td><\/tr>
kubectl uncordon node-name<\/td>Mark a previously cordoned node as schedulable again.<\/td><\/tr>
kubectl taint nodes node1 role=frontend:PreferNoSchedule<\/td>Applies a taint to a node to control Pod scheduling.<\/td><\/tr>
kubectl taint nodes node1 node2 dedicated=example:NoExecute<\/td>Can taint multiple nodes at once<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Pods<\/p>\n\n\n\n

Command<\/td>Explanation<\/td><\/tr>
kubectl get pods<\/td>Lists all nodes in the cluster with basic information<\/td><\/tr>
kubectl get pods -o wide<\/td>Lists nodes with additional information like IP Addresses and Node placement<\/td><\/tr>
kubectl get pods -n mynamespace<\/td>Lists all pods in the given namespace<\/td><\/tr>
kubectl get pods –watch<\/td>Watch all pods in the default namespace<\/td><\/tr>
kubectl get pods –field-selector=status.phase=Running<\/td>retrieves pods with a status of ‘Running’. Can be combined with label selectors also.<\/td><\/tr>
kubectl describe pod nginx<\/td>Shows detailed information about the pod named ‘nginx’<\/td><\/tr>
kubectl create -f pod-definition.yml<\/td>Creates a resource (pod) from the yaml file.<\/td><\/tr>
kubectl apply -f pod-definition.yml<\/td>Apply changes from the yaml file to the existing resources.<\/td><\/tr>
kubectl delete pod mypodname<\/td>Deletes the Pod named mypodname<\/code>.<\/td><\/tr>
kubectl delete pod\/nginx pod\/ubuntu –now<\/td>Immediately deletes the nginx<\/code> and ubuntu<\/code> Pods.<\/td><\/tr>
kubectl delete -f nginx.yaml<\/td>Deletes resources defined in nginx.yaml<\/code><\/td><\/tr>
kubectl create pdb nginx –selector=app=nginx –min-available=2<\/td>Creates a pod disruption budget to ensure at least two nginx pods remain available<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Replicas<\/p>\n\n\n\n

kubectl get replicationcontroller<\/td>Lists all replication controllers in the namespace.<\/td><\/tr>
kubectl get replicasets<\/td>Lists all replica sets in the namespace.<\/td><\/tr>
kubectl describe replicaset myapp-replicaset<\/td>Displays details about myapp-replicaset<\/code><\/td><\/tr>
kubectl edit replicaset myapp-replicaset<\/td>Opens an editor to modify myapp-replicaset<\/code>.<\/td><\/tr>
kubectl replace -f replicaset-definition.yml<\/td>Replaces the existing ReplicaSet with the definition in replicaset-definition.yml<\/code><\/td><\/tr>
kubectl scale -f replicaset-definition.yml –replicas=6<\/td>Scales the ReplicaSet defined in replicaset-definition.yml<\/code> to 6 replicas.<\/td><\/tr>
kubectl scale replicaset myapp-replicaset –replicas=6<\/td>Scales the myapp-replicaset<\/code> to 6 replicas<\/td><\/tr>
kubectl scale deployment\/nginx –replicas=6; watch kubectl get pods -o wide<\/td>Scales the nginx<\/code> Deployment to 6 replicas and monitors the Pod status.<\/td><\/tr>
kubectl delete replicaset myapp-replicaset<\/td>Deletes the ReplicaSet named myapp-replicaset<\/code><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Deployments<\/p>\n\n\n\n

kubectl create -f deployment-definition.yml<\/td>Creates resources defined in deployment-definition.yml<\/code><\/td><\/tr>
kubectl create -f deployment-definition.yml –record<\/td>Creates resources while recording the changes.<\/td><\/tr>
kubectl create deployment –image=nginx nginx<\/td>Creates a Deployment named nginx<\/code> with the nginx<\/code> image<\/td><\/tr>
kubectl get deployments<\/td>Lists all Deployments in the namespace.<\/td><\/tr>
kubectl rollout status deployment\/myapp-deployment<\/td>Checks the rollout status of myapp-deployment<\/code>.<\/td><\/tr>
kubectl rollout history deployment\/myapp-deployment<\/td>Shows the rollout history of myapp-deployment<\/code>.<\/td><\/tr>
kubectl rollout undo deployment\/myapp-deployment<\/td>Rolls back myapp-deployment<\/code> to the previous revision<\/td><\/tr>
kubectl set image deployment\/myapp-deployment nginx=nginx:1.9.1<\/td>Updates the image for nginx<\/code> container in myapp-deployment<\/code> to nginx:1.9.1<\/code><\/td><\/tr>
kubectl annotate deployment\/nginx kubernetes.io\/change-cause=”initial deployment”<\/td>Adds a change-cause annotation to the nginx<\/code> Deployment.<\/td><\/tr>
kubectl expose deployment nginx –port 80<\/td>Exposes the nginx<\/code> Deployment on port 80.<\/td><\/tr>
kubectl delete deployment myapp-deployment<\/td>Deletes the myapp-deployment<\/code> Deployment.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Namespaces<\/p>\n\n\n\n

kubectl create -f namespace-dev.yml<\/td>Creates a namespace using namespace-dev.yml<\/code>.<\/td><\/tr>
kubectl create namespace dev<\/td>Creates a namespace named dev<\/code>.<\/td><\/tr>
kubectl get namespaces (or) kubectl get ns<\/td>Lists all namespaces<\/td><\/tr>
kubectl delete namespace\/mynamespace –now<\/td>Immediately deletes the mynamespace<\/code> namespace.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Services & Endpoints<\/p>\n\n\n\n

kubectl get endpoints<\/td>Lists all service endpoints in the namespace<\/td><\/tr>
kubectl get services<\/td>Lists all services in the namespace<\/td><\/tr>
kubectl expose deployment nginx –type=NodePort<\/td>Exposes the nginx<\/code> deployment as a NodePort service<\/td><\/tr>
kubectl expose deployment nginx –type=LoadBalancer –port 8080 –target-port 80<\/td>Exposes nginx<\/code> on an external LoadBalancer.<\/td><\/tr>
kubectl create service externalname my-service –external-name nginx-red.default.svc.cluster.local<\/td>Creates an ExternalName service that points to a DNS address.<\/td><\/tr>
kubectl delete service\/nginx<\/td>Deletes the nginx<\/code> service<\/td><\/tr>
kubectl delete service\/nginix-blue service\/nginx-red service\/my-service<\/td>Delete multiple services<\/td><\/tr>
kubectl get serviceaccount<\/td>Lists all service accounts in the namespace.<\/td><\/tr>
kubectl create serviceaccount dashboard-sa<\/td>Creates a service account named dashboard-sa<\/code>.<\/td><\/tr>
kubectl describe serviceaccount dashboard-sa<\/td>Shows details of the dashboard-sa<\/code> service account.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Roles & Permissions<\/p>\n\n\n\n

<\/td><\/td><\/tr>
kubectl get clusterrolebindings -o wide<\/td>Lists cluster role bindings with detailed output.<\/td><\/tr>
kubectl describe ClusterRole\/cluster-admin<\/td>Shows details for the cluster-admin<\/code> role.<\/td><\/tr>
kubectl create clusterrole cluster-superuser1 –verb=’*’ –resource=’<\/em>*’<\/td>Creates a cluster role with full permission on all resources<\/td><\/tr>
kubectl create clusterrolebinding cluster-superuser1 –clusterrole=cluster-superuser1 –group=cluster-superusers1<\/td>Binds cluster role to a group<\/td><\/tr>
kubectl auth can-i ‘*‘ ‘<\/em>*’<\/td>Checks if the user has permissions for all actions on all resources.<\/td><\/tr>
kubectl auth can-i ‘*’ ‘<\/em>*’ –as-group=”cluster-superusers1″ –as=”msd”<\/td>Checks if user ‘msd<\/code>‘ has full permissions under the specified group<\/td><\/tr>
kubectl get roles<\/td>Lists all roles in the namespace.<\/td><\/tr>
kubectl get rolebindings<\/td>Lists all role bindings in the namespace.<\/td><\/tr>
kubectl describe role <ROLE_NAME><\/td>Shows details of the specified role.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Daemonsets<\/p>\n\n\n\n

kubectl get daemonsets<\/td>Lists all DaemonSets in the namespace.<\/td><\/tr>
kubectl describe daemonsets monitoring-daemon<\/td>Displays details of the monitoring-daemon<\/code> DaemonSet.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Jobs<\/p>\n\n\n\n

kubectl create job calculatepi –image=perl:5.34.0 — “perl” “-Mbignum=bpi” “print bpi(2000)”<\/td>Creates a job to calculate pi using a Perl script.<\/td><\/tr>
kubectl delete job calculatepi<\/td>Deletes the calculatepi<\/code> job.<\/td><\/tr>
kubectl delete job calculatepi –cascade=false<\/td>Deletes calculatepi<\/code> without cascading deletion.<\/td><\/tr>
kubectl delete jobs –all -n<\/td>Deletes all jobs in the specified namespace.<\/td><\/tr>
kubectl delete job myjob1 –grace-period=0 –force<\/td>Forcibly deletes myjob1<\/code> without waiting.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Storage & Persistent Volume<\/p>\n\n\n\n

kubectl get storageclass<\/td>Lists all storage classes<\/td><\/tr>
kubectl get persistentvolume<\/td>Liss all persistent volumes<\/td><\/tr>
kubectl get persistentvolumeclaim<\/td>Lists all persistent volume claims.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Labels, Configs & Sectrets<\/p>\n\n\n\n

kubectl config set-context $(kubectl config current-context) –namespace=prod<\/td>Sets the default namespace to prod<\/code> for the current context.<\/td><\/tr>
kubectl config use-context<\/td>Switches to a specified context.<\/td><\/tr>
kubectl config view<\/td>Displays the Kubernetes configuration settings.<\/td><\/tr>
kubectl config view –kubeconfig=\/home\/user\/custom-config.yaml<\/td>Views a specific kubeconfig file.<\/td><\/tr>
kubectl config view –raw<\/td>Displays the full, raw configuration<\/td><\/tr>
kubectl config set-context –current –namespace=mynamespace<\/td>Sets the default namespace for the current context to mynamespace<\/code>.<\/td><\/tr>
kubectl label namespace default istio-injection=enabled<\/td>Adds the istio-injection=enabled<\/code> label to the default<\/code> namespace.<\/td><\/tr>
kubectl label nodes node-name label-key=label-value<\/td>Adds a label to a node<\/td><\/tr>
kubectl create configmap myconfigmap –from-literal=COLOR=red –from-literal=City=chennai<\/td>Creates a configmap from literal values.<\/td><\/tr>
kubectl create configmap myconfigmap –from-env-file=config.properties<\/td>Creates a configmap from an env file<\/td><\/tr>
kubectl create secret docker-registry regcred –docker-server=private-registry.io –docker-username=user<\/td>Creates a docker registry secret<\/td><\/tr>
kubectl create token dashboard-sa<\/td>Generates a token for dashboard-sa<\/td><\/tr>
kubectl describe secret dashboard-sa-token-kbbdm<\/td>Show details of token<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Logs<\/p>\n\n\n\n

Command<\/td>Explanation<\/td><\/tr>
kubectl logs pod\/nginx<\/td>Retrieves logs from the pod named ‘nginx’ in the current namespace<\/td><\/tr>
kubectl logs pod\/nginx -c my-container -f<\/td>If your pod has multiple containers, specify the container name with -c. The -f flag (follow) streams the logs in real time.<\/td><\/tr>
kubectl logs pod\/nginx -c my-container -p<\/td>-p flag retrieves logs from previous instance of the container if it has restarted. Useful in debugging a crashed container.<\/td><\/tr>
kubectl logs pod\/nginx –all-containers=true<\/td>Get logs from all containers<\/td><\/tr>
kubectl logs -l app=mywebapp<\/td>Retrieves logs from all pods with label app=mywebapp.<\/td><\/tr>
kubectl logs deployment\/nginx<\/td>Retrieves logs from one of the pods in the ‘nginx’ deployment. Shows logs from a single pod only.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Scaling<\/p>\n\n\n\n

kubectl get hpa<\/td>Lists all horizontal pod autoscalers in the namespace<\/td><\/tr>
kubectl scale deployment my-deployment –replicas=5<\/td>Scale a deployment<\/td><\/tr>
kubectl scale replicaset my-replicaset –replicas=3<\/td>Scale a replicaset<\/td><\/tr>
kubectl scale statefulset my-statefulset –replicas=4<\/td>Scale a statefulset<\/td><\/tr>
kubectl autoscale deployment my-deployment –min=2 –max=10 –cpu-percent=80<\/td>Autoscale a deployment based on CPU usage<\/td><\/tr><\/tbody><\/table><\/figure>\n","protected":false},"excerpt":{"rendered":"

Getting Started Command Explanation minikube start –driver=virtualbox If you are not using Docker Desktop, minikube can help setup a cluster with Virtualbox as driver kubectl run hello-minikube –image=nginx Runs a Pod named hello-minikube with a nginx image. kubectl cluster-info Displays cluster information, including API server and core services URLs. kubectl run nginx –image=nginx –dry-run=client -o […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"var(--ast-global-color-4)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[20],"tags":[],"class_list":["post-67","post","type-post","status-publish","format-standard","hentry","category-k8"],"_links":{"self":[{"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/posts\/67","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/comments?post=67"}],"version-history":[{"count":8,"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/posts\/67\/revisions"}],"predecessor-version":[{"id":75,"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/posts\/67\/revisions\/75"}],"wp:attachment":[{"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/media?parent=67"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/categories?post=67"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/firewallsudhan.in\/index.php\/wp-json\/wp\/v2\/tags?post=67"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}