Kubernetes Command

kubectl.md

kubectl (command in default namespace)

• kubectl version
• kubectl api-versions
• kubectl cluster-info & kubectl cluster-info dump
• kubectl get namespace
• kubectl get all
• kubectl get cs or
• kubectl get nodes
• kubectl describe nodes
• Get the name of the Pod and store it in the POD_NAME environment variable:
  • export POD_NAME=$(kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}')
• Label a POD
  • kubectl label pod $POD_NAME app=v1
• Query PODs by the label
  • kubectl get pods -l app=v1
• kubectl get pods (in default Namespace)
  • get pod details in another namespace
    • kubectl get pods --namespace=kube-system
  • get pod in selector dev environment
    • kubectl get pods --selector env=dev
• All objects in prod environment
  • kubectl get all --selector env=prod
• Get POD which is 'prod', part of 'finance' BU and is a 'frontend' tier
  • kubectl get all --selector env=prod,bu=finance,tier=frontend
• kubectl get pods -o wide
• kubectl describe pods
• Get the container variable
  • kubectl exec POD_NAME env
• Enter into a container of a POD
  • kubectl exec -it POD_NAME bash
• To know details about one particular pod - kubectl describe pod POD_NAME
• kubectl get replicasets or kubectl get rs
• kubectl describe replicasets or kubectl describe rs
• kubectl get deployments
• kubectl describe deployments
• kubectl get services
• kubectl get sc
• kubectl get events

Create Pod

• kubectl create -f pod-definition.yml or kubectl create -f pod-definition.yml --namespace=dev (in dev namespace)
• Create a Pod with NGINX Image -
  • kubectl run nginx-pod --image=nginx --generator=run-pod/v1
  • kubectl run nginx-pod --image=nginx
• Generate POD Manifest YAML file (-o yaml). Don't create it(--dry-run)
  • kubectl run --generator=run-pod/v1 nginx-pod --image=nginx --dry-run -o yaml
• Delete a pod kubectl delete pod POD_NAME

Edit

• Edit the service named 'docker-registry': kubectl edit svc/docker-registry
• Use an alternative editor - KUBE_EDITOR="nano" kubectl edit svc/docker-registry
• Edit the service 'docker-registry' in JSON using the v1 API format:
  • kubectl edit svc/docker-registry --output-version=v1 -o json

Create a Deployment

• kubectl create deployment --image=nginx nginx-deployment
• Generate Deployment YAML file (-o yaml). Don't create it(--dry-run)
  • kubectl create deployment --image=nginx nginx-deployment --dry-run -o yaml
• Generate Deployment YAML file (-o yaml). Don't create it(--dry-run) with 4 Replicas (--replicas=4)
  • kubectl create deployment --image=nginx nginx-deployment --dry-run -o yaml > nginx-deployment.yaml
  • kubectl create deployment does not have a --replicas option. You could first create it and then scale it using the kubectl scale command.

Log View

• kubectl logs pod pod_name --namespace=kube-system
• If there are multiple containers in the POD definition file then use the name of the container to view the log of a particular container.
  • kubectl logs pod_name container-1_name

kubectl taint & toleration

• Get Nodes -> kubectl get nodes
• Check Taint on Node -> kubectl get nodes node01 | grep -i taint
• Apply Taint on Node -> kubectl taint nodes node01 spray=mortein:NoSchedule
• Untained Master Node -> kubectl taint nodes master node-role.kubernetes.io/master:NoSchedule-

Analytics View (need to install plugins like metrics-server)

• kubectl top node
• kubectl top pod