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Kubernetes – Kubectl Commands

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Pre-requisites: Kubernetes 

The Kubernetes command-line tool, kubectl, allows you to run commands against Kubernetes clusters. You can use kubectl to deploy applications, inspect and manage cluster resources, and view logs. Some basic Kubectl commands in a Kubernetes cluster are as follows:

kubectl Commands 

The most popular kubectl commands and flags are listed below.

1. Common Commands 

Name 

Commands

Run a two-replica nginx deployment 

kubectl run my-nginx –image=nginx –replicas=5 –port=80

Run and expose the Nginx pod

kubectl run my-nginx –restart=Never –image=nginx –port=80 –expose

Run nginx deployment and expose it 

kubectl run my-nginx –image=nginx –port=80 –expose

List of nodes and pods

kubectl get pod -o wide 

List all of them.

kubectl get all –all-namespaces

Get every service

kubectl get service –all-namespaces

Show labeled nodes

kubectl get nodes –show-labels

Using a dry run, verify the yaml file

kubectl create –dry-run –validate -f pod-GFG.yaml 

2. Check Performance

Name Command
learn about node resource use kubectl top node
Obtain pod resource use. kubectl top pod 
Get the resource utilization for the specified pod. kubectl top <podname> –containers
List each container’s resource usage. kubectl top pod –all-namespaces –containers=true 

3. Label & Annontation

Name Commands
By label, sort the pods kubectl get pods -l owner=gfg
Add a label by hand to a pod.  kubectl label pods <podname> owner=gfg
Remove label kubectl label pods <podname> owner- GFG

4.  Secrets 

Name Commands
List secrets kubectl get secrets –all-namespaces
Obtain a certain hidden field of sceret.  kubectl get secret GFG-cluster-kubeconfig

5. Service

Name Commands
List all services kubectl get services
List service endpoints kubectl get endpoints
Get service detail kubectl get service <servicename> -o yaml

6. Volumes & Volume Claims

Name Commands
List storage class kubectl get storageclass 
Check the mounted volumes kubectl exec storage<nameofpv>
Check to persist volume kubectl describe <nameofpv>

Kubectl apply

We can update or apply the configuration to a cluster with the aid of “kubectl apply”. With the help of the apply command, Kubernetes resources can be modified and created using a configuration file or a collection of configurations from a directory. 

Creating objects: The basic syntax of “kubectl apply”

kubectl apply -f <filename.yaml> 

Viewing and Finding Resources

These commands are used to show all the resources. It works like a READ operation. It is used to view resources like nodes, deployments, services, config maps, etc. 

$ kubectl get <resource>
  • Getting all Resources: The “kubectl get all” command enables us to view all of the cluster’s resource
Getting all Resources

 

  • Getting  Nodes: The number of available nodes in the cluster will be displayed by “Kubectl get nodes”
Getting  Nodes

 

  • Getting Pods: “Kubectl get pod” can be used to find out how many pods are scheduled in the cluster.
Getting Pods

 

  • Getting Services: “Kubectl get service” can be used to list the services that have been created in the cluster.
Getting Services

 

Creating Resources

These commands are used to create resources like deployments, services, secrets, config maps, etc.

$ kubectl create <resource_type> <resource_name> OPTIONS
  • Creating Deployment: The command creates a deployment named nginx-depl using the image Nginx.
Creating Deployment

 

  • Creating service: The command in the creates a service of type node port named nginx and it is exposed on port 80 of the local machine
Creating service

 

Editing Resources

After running the command below you can update the resource configuration file and if there are any changes the resource will be updated according to it.

kubectl edit <resource_type> <resource_name>
  • Updating Deployment: The command in the below output opens a Vim-like editor in the terminal to edit the Nginx-deal deployment config file.
Updating Deployment

 

  • Updating Service: The command opens a vim-like editor in the terminal to edit the Nginx service config file.
Updating Service

 

Deleting Resources

These commands are used to delete resources like deployments, services, config maps, pods, secrets, etc. You can choose a particular resource name of a resource type or you can also delete all resources of a resource type by specifying –all flag

kubectl delete <resource_type> <resource_name> | --all
  • Deleting Deployment: The command deletes a deployment named nginx-depl.
Deleting Deployment

 

  • Deleting Service: The command deletes a service named Nginx.
Deleting Service

 

Using Configuration File for CRUD

These commands are used to use YAML configuration files for CRUD operations in a cluster.

  • Applying a Config file: The command creates the resource if it does not exist or updates it if it already exists according to the configuration in the YAML file mentioned after the -f flag.
$ kubectl apply -f [file-name]
Applying a Config file

 

  • Deleting using Config file: The command deletes the resource that was created using the YAML config file mentioned after the -f flag/ 
$ kubectl delete -f [file-name]
Deleting using Config file

 

Interacting with running Pods

  • Viewing Logs of a Pod: The command shows the logs of the pod mentioned once the pod started.
$ kubectl logs [pod-name]
Viewing Logs of a Pod

 

  • Get an Interactive terminal for a pod: The command starts an interactive terminal of the Nginx pod so that we can control the pod directly through its terminal.
$ kubectl exec -it [pod-name] -- bin/bash
Get an Interactive terminal for a pod

 

  • Get info about a Resource: The command gives details about the nginx deployment
$ kubectl describe <resource_type> [resource-name]
Get info about a Resource

 

Copying Files and Directories to and from Containers

With the help of the “kubectl cp” command, we can copy files from host to container and vice versa.

The basic syntax of “kubectl  cp”

kubectl cp <host path pod name:container path> 

This command will only function if the “tar” command in the container images is present or the command failed to run. 

Updating Resources

The “kubectl get rs” command allows us to check the list of deployments, To update them, look up the revision history of prior deployments, and roll back to a specific revision if necessary. Using the following commands. 

kubectl rollout <history> , <undo> , <status>, <restart> 


Last Updated : 25 Apr, 2023
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