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
- Basic understanding of Kubernetes
- 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?
- Important Commands
- Cluster Information
- Configuration Information
- Namespace
- Pod
- Deployments
- Services
- 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.
