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 seconds.

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 18.04 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 of 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 [email protected] is the context name

kubectl config  use-context [email protected]

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 namespaceAdvertisement

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 label app=myapp.

Then:

Create a pod with 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.