Cheat Sheet for Kubernetes Commands

While working on Kubernetes it is very important that you know at least the basic commands. In this article, you will find the commands which are needed most of the time while working on the cluster. If you know commands then you can get rid of writing object definition files for simple objects and then creating objects using those files. Instead, you can use the commands and see objects created within a fraction of a second.

In this article, you will not only see the commands to get details of the objects but also for creating the objects. This article is focused on only commands and not a description of those commands. If you want to know each and every command in detail, you can visit the official documentation here.

This article will be a cheat sheet for you with respect to the core objects in the Kubernetes Cluster.

Pre-requisites

1. Basic understanding of Kubernetes
2. Kubernetes Cluster with at least 1 worker node.
   If you want to learn to create a Kubernetes Cluster, click here. This guide will help you create a Kubernetes cluster with 1 Master and 2 Nodes on AWS Ubuntu EC2 Instances. 

What will we see?

1. Important Commands
   1. Cluster Information
   2. Configuration Information
   3. Namespace
   4. Pod
   5. Deployments
   6. Services
   7. Manage Objects from .yaml/.yml files

Important Commands

Cluster Information 

Print the client and server version information
kubectl version

Print the supported API resources on the server
kubectl api-resources

Print the supported API versions on the server, in the form of “group/version”
kubectl api-versions

Print the cluster information
kubectl cluster-info

Get the list of the nodes in the cluster
kubectl  get nodes

Get information of the master node
kubectl  get nodes master -o wide

Get detailed information on the master nodes
kubectl  describe  nodes  master

Configuration Information

Display merged kubeconfig settings
kubectl  config view

View the current context
kubectl  config  current-context

Set the context, here kubernetes-admin@kubernetes is the context name
kubectl config  use-context kubernetes-admin@kubernetes

Display clusters defined in the kubeconfig
kubectl  config get-clusters

Describe one or many contexts
kubectl  config get-contexts

Namespaces

Get all namespaces
kubectl  get namespaces

Get namespace information in yaml format
kubectl  get namespaces -o yaml

Describe the default namespace
kubectl  describe  namespace default

Create a new namespace
kubectl  create namespace my-namespace

Delete the namespace
kubectl  delete namespace my-namespace

Pods

Get pods from the current namespace
kubectl get pods

Get pods from all the namespaces
kubectl get pods --all-namespaces

Get pods from the specified namespace
kubectl get pods -namespace=my-namespace

Create a pod 
kubectl  run my-pod-1 --image=nginx:latest --dry-run

see how the pod would be processed
kubectl  run my-pod-1 --image=nginx:latest --dry-run=client

Create a pod in the specified namespace
kubectl  run my-pod-2 --image=nginx:latest --namespace=my-namespace

Create a pod with a label to it
kubectl  run nginx --image=nginx -l --labels=app=test

Get all pods with label output
kubectl get pods --show-labels

Get pods with exapanded/wide output
kubectl  get pods -o wide

List pods in a sorted order
kubectl  get pods --sort-by=.metadata.name

Get logs of the pod
kubectl  logs  my-pod-1

Get pods within the specified namespace with exapanded/wide output
kubectl get pods my-pod-2 --namespace=my-namespace -o wide

Get logs of the pod within the specified namespace
kubectl  logs  my-pod-2 --namespace=my-namespace

Describe the pod
kubectl  describe  pod my-pod-1

Describe the pod within the specified namespace
kubectl describe  pods my-pod-1 --namespace=my-namespace

Delete the pod from the current namespace
kubectl  delete pod my-pod-1

Delete the pod from the specified namespace
kubectl delete  pods my-pod-1 --namespace=my-namespace

Deployments

Get a list of deployments from the current namespace
kubectl  get deployments

Get a list of deployments from the specified namespace
kubectl  get deployments --namespace=my-namespace

Create a deployment
kubectl  create deployment my-deployment-1 --image=nginx

Get the specified deployment
kubectl  get deployment my-deployment-1

Get the specified deployment with its labels
kubectl  get deployment my-deployment-1 --show-labels

Describe the specified deployment 
kubectl describe  deployments my-deployment-1

Get details of the deployment in yaml format
kubectl  get deployment my-deployment-1 -o yaml

Change image in the existing deployment
kubectl  set image deployment my-deployment-1 nginx=nginx:1.16.1

View rollout history
kubectl rollout history deployment my-deployment-1

Undo a previous rollout
kubectl rollout undo deployment my-deployment-1

Go back the specific version of the rollout history
kubectl rollout undo deployment my-deployment-1 --to-revision=2

Show the status of the rollout
kubectl rollout status deployment my-deployment-1

Restart a resource
kubectl rollout restart deployment my-deployment-1

Scale deployment to 3
kubectl scale --replicas=3 deployment my-deployment-1

Scale from current count to the desired
kubectl scale --current-replicas=3 --replicas=5 deployment my-deployment-1

This will create an HPA (Horizontal Pod Aotuscaler)
kubectl autoscale deployment my-deployment-1 --min=2 --max=10

Services

First, create a pod with the label app=myapp.

Then:

Create a pod with a label
kubectl run my-pod --image=nginx --labels=app=myapp

Create a service of type NodePort which will use pod’s labels for selector but we have to specify the type, so create a definition file first and then create a service
kubectl expose pod my-pod --port=80 --name nginx-service --type=NodePort --dry-run=client -o yaml

Create a Service which will have type type NodePort but this will not have selector as my-app
kubectl create service nodeport nginx --tcp=80:80 --node-port=30080 --dry-run=client -o yaml

Get services from the current context
kubectl  get service

Get details of the services
kubectl  get service -o wide

Get services with labels on them
kubectl  get service --show-labels

Get services from all the namespaces
kubectl  get services --all-namespaces

Describe the service to know more about it
kubectl  describe  service nginx-service

Get a particular service
kubectl  get  service nginx-service

Delete the service 
kubectl  delete service nginx-service

Manage Objects from .yaml/.yml files

First, create a definition file for a pod

Create a definition file for pod 
kubectl  run mypod --image=nginx --dry-run=client -o yaml > my-pod.yml

Create an object 
kubectl  create -f my-pod.yml

Delete the object 
kubectl  delete -f my-pod.yml

Conclusion

In this article, we saw the important commands which are needed while working on Kubernetes. Commands in Kubernetes are not limited to only these commands but these commands are like “must-know” commands.