curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
sudo install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl

kubectl version --client

kubectl get namespaces --show-labels
kubectl get namespaces <name>
kubectl describe namespaces <name>

kubectl run <app-name> --image=<image> --port=<port>
kubectl expose pod <app-name> --name=<app-service-name>  --port=<port> --type=NodePort
kubectl get all -o wide
kubectl port-forward <pod-name> --address 0.0.0.0 <source>:<target>

Minikube start

minikube start -n 3 -p <profile-name>
minikube profile list
minikube stop -p <profile-name>
minikume delete -p <profile-name>

Minikube dashboard

minikube dashboard

Run the following command: (for minikube)

minikube service <appname>
minikube service --url <appname>
minikube service --url <appname> -n <namespace>

Creating a new namespace

Create a new YAML file called my-namespace.yaml with the contents:

apiVersion: v1
kind: Namespace
metadata:
  name: <namespace>

Then run:

kubectl create -f ./my-namespace.yaml

Alternatively, you can create namespace using below command:

kubectl create namespace <namespace>

Assign Resource Quota To Namespace

Create a file named resourceQuota.yaml. Here is the resource quota YAML contents.

apiVersion: v1
kind: ResourceQuota
metadata:
  name: mem-cpu-quota
  namespace: <namespace>
spec:
  hard:
    requests.cpu: "4"
    requests.memory: 8Gi
    limits.cpu: "8"
    limits.memory: 16Gi

Create the resource quota using the YAML.

kubectl create -f resourceQuota.yaml

Now, let’s describe the namespace to check

kubectl describe ns <namespace>

Deleting a namespace

kubectl delete namespaces <namespace>

Getting namespace logs

kubectl get events -n <namespace>

Create a Deployment

kubectl create deployment <deployment-name> --image=k8s.gcr.io/echoserver:1.4

Create pods in each namespace

kubectl create deployment <deployment-name> --image=k8s.gcr.io/sechoserver:1.4 -n=development --replicas=2

View the Deployment:

kubectl get deployment
kubectl get deployment -n=<namespace>
kubectl get deployment <deployment-name> -n <namespace> --output yaml

View the Pod:

kubectl get pods
kubectl get pods -w
kubectl get pods -n=<namespace>
kubectl get pods -l app=<appname> -n=<namespace>
kubectl get pods --all-namespaces 
kubectl get pods --all-namespaces -o wide
kubectl get pod <pod-name> -o yaml
kubectl get pods --show-labels
kubectl get pods --output=wide
watch -n 1 "kubectl get pods -o wide"

Connecting Pod:

kubectl exec -it <pod-name> -- /bin/bash
kubectl exec <pod-name> cat /etc/resolv.conf  //Check Pod resolv.conf file to see
kubectl exec -ti <pod-name> -- nslookup kubernetes.default  //Check the Pod DNS
kubectl exec -it <multi-container-pod> -c <container-name> /bin/bash   //Login into the container
kubectl exec -it <pod-name> -- mysql -u root -p

Delete Pod

kubectl delete pods --all --namespace <namespace>

Scale deployment

kubectl scale deployment <node-name> --replicas=5 -n=<namespace>

View the Node:

kubectl get nodes

View cluster events:

kubectl get events

View the kubectl configuration:

kubectl config view

Create a Service

kubectl expose deployment <deployment-name> --type=LoadBalancer --port=<pod-port>
kubectl expose deployment <deployment-name> --type=NodePort --port=<pod-port>

View the Service you created:

kubectl get services
kubectl describe service <service-name> -o json

View the Pod and Service you created:

kubectl get pod,svc -n kube-system

View the Pod logs:

kubectl logs <pod-name>
kubectl logs <pod-name> -c <container-name>

View the Pod details:

kubectl describe pod <pod-name>

Update the image of your Deployment:

kubectl set image deployment/hello-node hello-node=hello-node:v2

Clean up

kubectl delete service <service-name>
kubectl delete deployment <deployment-name>
kubectl delete -f <yaml-file>

context

kubectl config view
kubectl config get-contexts
kubectl config set-context <context-name> --namespace=<namespace-name> --user=kubernetes-admin --cluster=kubernetes
kubectl config use-context <context-name> 
kubectl config use-context kubernetes-admin@kubernetes

nodeSelector

kubectl get nodes <node-name> --show-labels
kubectl label node <node-name> <label-name>=<label-value>
kubectl label node <node-name> <label-name>-
kubectl describe node <node-name>

PersistentVolume for Storage

kubectl get pv <pv_name>  // View information about the PersistentVolume:
kubectl get pvc <pvc-name> 
kubectl describe pvc <pvc-name> 
kubectl describe pv <pv_name> 

Secrets

kubectl create secret generic <secret-name> --from-literal=username=admin --from-literal=password=1234
kubectl describe secrets <secret-name>
kubectl get secret <secret-name> -o jsonpath='{.data.<key>}' | base64 --decode
kubectl get secrets <secret-name> -o yaml
echo '<value>' | base64
echo '<base64-value>' | base64 --decode
kubectl delete secret <secret-name>

Configmap

kubectl create configmap <map-name> <data-source>
kubectl create configmap <configmap-name> --from-literal=demo=Hello-world
kubectl create configmap file-cm --from-file=config-files/
kubectl describe configmap <configmap-name>
kubectl get cm
kubectl get cm <configmap-name> -o yaml

kubectl api-resources
kubectl run <name> --image=nginx
kubectl run -it --restart=Never --rm --image busybox:1.28 dns-test
kubectl rollout history <deployment-name>
kubectl rollout undo <deployment-name> --to-revision=1
kubectl rollout restart deployment <deployment-name> -n <namespace>

Imperative CronJob

kubectl create cronjob my-cron --image=busybox --schedule="*/5 * * * *" -- echo hello
kubectl edit cronjob/my-cron
KUBE_EDITOR="nano" kubectl edit cronjob/my-cron
kubectl delete cronjob my-cron

Add new Node

sudo apt-get update

sudo apt-get install -y apt-transport-https ca-certificates curl

sudo curl -fsSLo /usr/share/keyrings/kubernetes-archive-keyring.gpg https://packages.cloud.google.com/apt/doc/apt-key.gpg

echo "deb [signed-by=/usr/share/keyrings/kubernetes-archive-keyring.gpg] https://apt.kubernetes.io/ kubernetes-xenial main" | sudo tee /etc/apt/sources.list.d/kubernetes.list

sudo apt-get update

sudo apt-get install -y kubelet kubeadm kubectl

sudo apt-mark hold kubelet kubeadm kubectl

kubeadm token create --print-join-command

Maintance Node

kubectl cordon <node-name>      # To mark a Node unschedulable
kubectl drain <node-name>       # remove pods --ignore-daemonsets
kubectl uncordon <node-name>    # Activate node
kubectl delete node <node-name> # Delete Node

cat <<EOF | kubectl apply -f -
.....
EOF