Some useful commands in kubectl

Introduction to kubectl
Basic commands in Kubectl
Deploy commands in Kubectl
Cluster management commands
Troubleshooting and debugging commands
Advanced commands
Wrapping up

Introduction to kubectl

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.

The common format of a kubectl command is:

kubectl <action> <resource> <name-resource>

This performs the specified action (like create, describe) on the specified resource (like node, container) with its name.

To know more about resource types, we can following the link.

Basic commands in Kubectl

Belows are some basic kubectl commands:

Check version of kubernetes clusters

If you want to check client and server’s version of Kubernetes cluster, use this command.
```
 kubectl version
```
For example:
Create a resource for cluster

Create a resource from a file or from stdin.

For example, create a Kubernetes deployment from the file.
```
 kubectl create <resource-name>
```
For example:
- let’s deploy our app on kubernetes with the deployment name and app image location
```
  kubectl create deployment kubernetes-bootcamp --image=gcr.io/google-samples/kubernetes-bootcamp:v1
```
  This performed a few things for you:
  - searched for a suitable node where an instance of the application could be run.
  - scheduled the application to run on that Node.
  - configured the cluster to reschedule the instance on a new Node when needed.
View the resources in the cluster
```
 kubectl get <resource-name>
```
For example:
- View the nodes in the cluster
```
  kubectl get nodes
```
- View our deployments
```
  kubectl get deployments
```
  Then, we have:
- Get a list of running pods or the YAML output of a pod.
Run a particular image on the cluster
```
 kubectl run 
```
Set specific features on on objects
```
 kubectl set
```
For example:
- set environment variables
- update a Docker image in a pod template
- …
Take a service, deployment, or pod and expose it as a new Kubernetes Service
```
 kubectl expose
```
Get the documentation of resources
```
 kubectl explain
```
For example:
- the documentation on deployments
Edit a resource
```
 kubectl edit
```
For example:
- edit a deployment
Delete resources by filenames, stdin, resources, and names, or by resources and label selectors
```
 kubectl delete
```

Deploy commands in Kubectl

Manage the rollout of a resource
```
 kubectl rollout
```
Set a new size for a deployment, ReplicaSet, or StatefulSet
```
 kubectl scale
```
Auto-scale a deployment, ReplicaSet, or StatefulSet
```
 kubectl autoscale
```

Cluster management commands

Modify certificate resources
```
 kubectl certificate
```
Display cluster information
```
 kubectl cluster-info
```
Display resource (CPU/memory/storage) usage
```
 kubectl top
```
Mark a node as unschedulable
```
 kubectl cordon
```
Mark a node as schedulable
```
 kubectl uncordon
```
Drain a node in preparation for maintenance
```
 kubectl drain
```
Update the taints on one or more nodes
```
 kubectl taint
```

Troubleshooting and debugging commands

Show the details of a specific resource or group of resources
```
 kubectl describe
```
Print the logs for a container in a pod
```
 kubectl logs
```
Attach to a running container
```
 kubectl attach
```
Execute a command in a container
```
 kubectl exec
```
Forward one or more local ports to a pod
```
 kubectl port-forward
```
Run a proxy to the Kubernetes API server
```
 kubectl proxy
```
Copy files and directories to and from containers
```
 kubectl cp
```
Inspect authorization
```
 kubectl auth
```

Advanced commands

Show difference of live version against a would-be applied version
```
 kubectl diff
```
Apply a configuration to a resource by filename or stdin
```
 kubectl apply
```
Update the fields of a resource using a strategic merge patch
```
 kubectl patch
```
Replace a resource by filename or stdin
```
 kubectl replace
```
Wait for a specific condition on one or many resources
```
 kubectl wait
```
Convert config files between different API versions
```
 kubectl convert
```
Build a customization target from a directory or a remote URL
```
 kubectl kustomize
```

Wrapping up

Refer:

https://kubernetes.io/docs/reference/kubectl/cheatsheet/

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