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Kubernetes cheat sheet

·7 mins·
Kubernetes
Table of Contents

Commands
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Reference: https://kubernetes.io/docs/reference/generated/kubectl/kubectl-commands https://kubernetes.io/docs/reference/kubectl/conventions/

Controlplane
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Action Command
ETCD certficates –cacert /etc/kubernetes/pki/etcd/ca.crt
–cert /etc/kubernetes/pki/etcd/server.crt
–key /etc/kubernetes/pki/etcd/server.key
ETCD commands etcdctl snapshot save
etcdctl endpoint health
etcdctl get
etcdctl put
etcdctl version
Static pods default folder /etc/kubernetes/manifests

JSON PATH
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Action Command
Get restart count of a container $.status.containerStatuses[?(@.name == 'redis-container')].restartCount
Query all the pod names $[*].metadata.name
Query to get all user names. $.users.[*].name
Get node names and export to file k get nodes -o=jsonpath={'.items[*].metadata.name'} >> /opt/outputs/node_names.txt
Get node OS images kubectl get nodes -o jsonpath='{.items[*].status.nodeInfo.osImage}' > /opt/outputs/nodes_os.txt
Get user names from kubeconfig file and export to file k config view --kubeconfig=/root/my-kube-config -o=jsonpath={'.users[*]'} >> /opt/outputs/users.txt

Containers
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Action Docker Podman
Build dockerfile docker build -t <imagename>:<tag> . podman build -t <imagename>:<tag> .
Run container image docker run -d -p 8080:80 <imagename>:<tag> docker run -d -p 8080:80 <imagename>:<tag>
Get logs for container docker logs <containername or containerid> podman logs <containername or containerid>
Interactive mode in container docker exec -it <containername or containerid> sh podman exec -it <containername or containerid> sh
Get all running and exited containers docker ps -a podman ps -a
Get images docker images podman images
Remove image docker image rm <imagename> podman image rm <imagename>
Remove all images not in use (dangling images) docker image prune -a podman image prune -a
Remove all images docker rmi ($docker images -q) podman rmi ($docker images -q)
Stop and remove all containers docker stop $(docker ps -a -q) && docker rm $(docker ps -a -q) podman stop $(podman ps -a -q) && podman rm $(podman ps -a -q)

Kubernetes
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Kubectl configurations
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Action Command
Set alias for kubectl in Bash alias k=kubectl
Set alias for kubectl with completion in Bash alias k=kubectl complete -o default -F __start_kubectl k
Set alias for kubectl in Powershell Set-Alias -Name k -Value kubectl
Get kubectl version kubectl version
Get cluster info

 kubectl cluster-info
Display kubeconfig settings kubectl config view
Get kubeconfig contexts kubectl config get-contexts
Get current context kubectl config current-context
Set context kubectl config set-context <contextname>

kubectl config set-context <contextname> --namespace=<namespacename>

kubectl config use-context nginx
Change to another context kubectl config use-context <contextname>
Change namespace in current context kubectl config set-context --current --namespace=<namespacename>
Delete context kubectl config delete-context nginx

Get Info
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Action Command
Get events kubectl get events

kubectl get events --field-selector involvedObject.name=nginx
Show the total CPU and memory in use by the nodes kubectl top nodes
Show Pods and their resource usage.
By default it only displays Pods in the current namespace, but you can add the –all-namespaces flag to see resource usage
by all Pods in the cluster.		 kubectl top pods

kubectl top pods --all-namespaces
Get all resources Kubectl get all --all-namespaces
Get all resources based on labels Kubectl get all --selector env=prod

kubectl get all --selector env=prod,bu=finance,tier=frontend
Get all pods from all namespaces kubectl get pod -A
Get pods based on labels Kubectl get pods --selector env=dev

kubectl get pods --selector env=prod,bu=finance,tier=frontend
Get more information about a particular object kubectl describe <resource-name> <obj-name>

kubectl describe nodes node-1

Namespace
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Action Command
Create namespace kubectl create ns \<namespacename>
kubectl create -f .\namespaces.yml
Get all resources in a namespace kubectl --namespace \<namespacename> get all
Change namespace context kubectl config set-context --current --namespace \<namespacename>
Get namespaces kubectl get namespace
kubectl get ns
Get namespaces details kubectl describe namespace
kubectl describe ns

Pods
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Action Command
Create pod - imperative kubectl run nginx-app --image=nginx
Create pod - declarative kubectl apply -f pod-manifest.yaml
Update pod - declarative kubectl replace -f pod-manifest.yaml --force
Delete pod kubectl delete pod <podname>
Get pod IP kubectl get pods nginx -o jsonpath --template={.status.podIP}
Get logging for pod kubectl logs nginx-pod

kubectl logs nginx-pod -c nginx-container

# Stream logs
kubectl logs nginx-pod -f
Generate Pod manifest file

–dry-run: Will not create the resource, but whether the resource can be created and if your command is right.		 kubectl run nginx --image=nginx --dry-run=client -o yaml > nginx.yaml

kubectl get pod nginx --dry-run=client -o yaml > nginx.yaml
Run temporary test pod kubectl run --rm -i <podname> --image=<imagename> --restart=Never -- <command> <br><br> Example: <br>kubectl run --rm -i test-curl-pod --image=curlimages/curl --restart=Never -- curl -m 2 testnginx-svc<br>k run tmp --restart=Never --rm --image=nginx:alpine -i -- curl http://project-plt-6cc-svc.pluto:3333
Execute a command in a running container

This will provide an interactive shell inside the running container.		 kubectl exec -it nginx -- bash
Attach to the running process in a container

This is usefull when there is no terminal like bash available in the container.
It is similar to kubectl logs but allows to send input to the running process, assuming that process is set up to read from
standard input.		 kubectl attach -it <pod-name>
Access pod through a secure network tunnel.

Forwards network traffic from the local machine to the pod.
Can be used for pods and services. (With services, the request will only be forwarded to a single Pod and will not go through the load balancer)
kubectl port-forward <pod-name> 8080:80

kubectl port-forward services/<service-name> 8080:80
Copy local file to running container, or file from running container to local.

Can also be used to specify directories.		 kubectl cp <pod-name>:</path/to/remote/file> </pat h/to/local/file>

kubectl cp </pat h/to/local/file> <pod-name>:</path/to/remote/file>

Change commands
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Action Command
Edit a Kubernetes resource (interactive instead of the local file)
It downloads the latest object state and then launch an editor that contains the definition to change		 kubectl edit <resource-name> <obj-name>
Apply a Kubernetes manifest file

The apply command also records the history of previous configurations in an annotation within the object.		 kubectl apply -f <filename>.yaml

kubectl apply -f <filename>.yaml view-last-applied
Replace a Kubernetes resource with a Kubernetes manifest file kubectl replace -f <filename>.yaml

kubectl replace --force -f <filename>.yaml

Services
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Action Command
Expose pod kubectl expose pod <podname> --port=<portnumber> --name <servicename>

kubectl expose pod <podname> --type=NodePort --port=<portnumber> --name <servicename>
Expose deployment kubectl expose deployment <deploymentname> --port=<portnumber> --name <servicename>

kubectl expose deployment <deploymentname> --type=NodePort --port=<portnumber> --name <servicename>
Create service (ClusterIP) kubectl create service clusterip <servicename> --tcp=<port>:<targetport>
Create service (NodePort) kubectl create service nodeport <servicename> --tcp=<port>:<targetport>
Delete Service kubectl delete service <servicename>

kubectl delete svc <servicename>

Deployments
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Action Command
Get deployments kubectl get deployments

kubectl get deploy
Create a deployment kubectl create deployment --image=nginx nginx-deployment

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

kubectl create -f <deploymentdefinition>.yaml
Update deployment kubectl apply -f <deploymentdefinition>.yaml

kubectl set image deployment/<deploymentname> <containername>=<newimagename>:<newimagetag>
Delete deployment kubectl delete deployment nginx-deployment
Generate Deployment manifest file

–dry-run: Will not create the resource, but whether the resource can be created and if your command is right.		 kubectl create deployment --image=nginx nginx --dry-run=client -o yaml > nginx-deployment.yaml

kubectl create deployment --image=nginx nginx --replicas=4 --dry-run=client -o yaml > nginx-deployment.yaml

kubectl get deployment nginx-deployment --dry-run=client -o yaml > nginx-deployment.yaml
Scale a deployment kubectl scale deployment nginx --replicas=4
Get deployment rollout status kubectl rollout status deployment/nginx

kubectl rollout history deployment/nginx
Rollback a deployment rollout kubectl rollout undo deployment/nginx

ReplicaSets
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Action Command
Get replicasets kubectl get replicasets

kubectl get rs
Create a replicasets kubectl create -f <replicasetdefinition>.yaml
Update replicasets kubectl edit replicaset <replicasetname>

kubectl replace -f <replicasetdefinition>.yaml

kubectl apply -f <replicasetdefinition>.yaml
Delete replicasets kubectl delete replicaset nginx-replicaset
Generate Replicaset manifest file

–dry-run: Will not create the resource, but whether the resource can be created and if your command is right.		 kubectl get replicaset nginx-replicaset --dry-run=client -o yaml > nginx-replicaset.yaml

Secrets
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Action Command
Get secrets kubectl get secrets

kubectl describe secret <secretname>
Create generic secret kubectl create secret generic my-secret --from-literal=key1=supersecret --from-literal=key2=topsecret
Decode secret kubectl get secret <secretname> -n <namespace> -o jsonpath={.data}

echo <base64string> | base64 -d
Delete secret kubectl delete secret <secretname>

ACR
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Action Command
Login ACR az acr login --name \<acrname>
Tag image docker tag \<imagename>:\<tag> \<acrname>.azurecr.io/\<containername>:\<tag>
Push image to ACR docker push \<acrname>.azurecr.io/\<containername>:\<tag>
List images in ACR az acr repository list --name <acrname> --output table
Get image info az acr repository show -n <imagename>  --repository <acrname>
List tags for image az acr repository show-tags --name <acrname> --repository <repositoryname> --output table
Import image from other ACR az acr import --name <acrname> --source <imagename>:<imagetag> --image <destinationimagename>:<destinationimagetag> --registry /subscriptions/00000000-0000-0000-0000-000000000000/resourceGroups/<resourcegroupname>/providers/Microsoft.ContainerRegistry/registries/<acrname>

az acr import --name acrvcofitv3 --source cibuildagent:latest --image cibuildagent:latest --registry /subscriptions/25e085bc-32a8-432a-a062-581a222b9e17/resourceGroups/RG-AUTOMATION-EBPI/providers/Microsoft.ContainerRegistry/registries/acrvcofit