The idea behind this post is to have a list of kubernetes commands that could be useful. I’ll keep adding to it over time, any comments welcome

K9S
K9S is a command-line interface (CLI) tool that allows you to manage Kubernetes clusters from the terminal. It provides an intuitive user interface and helps you quickly navigate through resources in your cluster.
https://vinsanity.uk/2023/05/02/installing-k9s-on-kubernetes/

Kubectl version
The current version of Kubernetes is installed.

kubectl get nodes

kubectl proxy
The proxy server is operational. The proxy service starts in a few minutes.

kubectl get namespaces

kubectl get pods -A
-A indicates the flag for all namespaces.

Kubectl create namespace *name*

kubectl describe pod *PODName* -n *Namespace*
The detailed breakdown of the pod appears in the namespace

kubectl config set-context --current --namespace=*Namespace*
To swap namespaces permanently

kubectl describe secrets
To access the security token for the admin account created

k config use-context tkg-workload-cluster-01-admin@tkg-workload-cluster-01

k get nodes -o wide

k get svc -n

k expose -n vulnapps-dev deployment drupal --type=NodePort

Imperative Commands with Kubectl

While you would be working mostly the declarative way - using definition files, imperative commands can help in getting one time tasks done quickly, as well as generate a definition template easily.

--dry-run: By default as soon as the command is run, the resource will be created. If you simply want to test your command , use the --dry-run=client option. This will not create the resource, instead, tell you whether the resource can be created and if your command is right.

-o yaml: This will output the resource definition in YAML format on screen.

Use the above two in combination to generate a resource definition file quickly, that you can then modify and create resources as required, instead of creating the files from scratch.

POD
Create an NGINX Pod

kubectl run nginx --image=nginx

Generate POD Manifest YAML file (-o yaml). Don't create it(--dry-run)

kubectl run nginx --image=nginx --dry-run=client -o yaml

Deployment
Create a deployment

kubectl create deployment --image=nginx nginx

Generate Deployment YAML file (-o yaml). Don't create it(--dry-run)

kubectl create deployment --image=nginx nginx --dry-run=client -o yaml



Generate Deployment with 4 Replicas

kubectl create deployment nginx --image=nginx --replicas=4



You can also scale a deployment using the kubectl scale command.

kubectl scale deployment nginx --replicas=4

Another way to do this is to save the YAML definition to a file and modify

kubectl create deployment nginx --image=nginx --dry-run=client -o yaml > nginx-deployment.yaml



You can then update the YAML file with the replicas or any other field before creating the deployment.



Service
Create a Service named redis-service of type ClusterIP to expose pod redis on port 6379

kubectl expose pod redis --port=6379 --name redis-service --dry-run=client -o yaml

(This will automatically use the pod's labels as selectors)

Or

kubectl create service clusterip redis --tcp=6379:6379 --dry-run=client -o yaml (This will not use the pods labels as selectors, instead it will assume selectors as app=redis. You cannot pass in selectors as an option. So it does not work very well if your pod has a different label set. So generate the file and modify the selectors before creating the service)



Create a Service named nginx of type NodePort to expose pod nginx's port 80 on port 30080 on the nodes:

kubectl expose pod nginx --type=NodePort --port=80 --name=nginx-service --dry-run=client -o yaml

(This will automatically use the pod's labels as selectors, but you cannot specify the node port. You have to generate a definition file and then add the node port in manually before creating the service with the pod.)

Or

kubectl create service nodeport nginx --tcp=80:80 --node-port=30080 --dry-run=client -o yaml

(This will not use the pods labels as selectors)

Both the above commands have their own challenges. While one of it cannot accept a selector the other cannot accept a node port. I would recommend going with the kubectl expose command. If you need to specify a node port, generate a definition file using the same command and manually input the nodeport before creating the service.