Kubernetes cheatsheet

Kubernetes is an orchestration framework for containers that give you portability for managing containerized workloads and services in form of pods, there are two types of CLI commands -

Imperative - imperative commands are one-liners commands.
Declarative - declarative has some definition of objects in a file that a developer can refer it again.
There are different CLI tools that allow you to run commands against the Kubernetes cluster some of which I attempted to collect and put together as below.

Function	Command
kubectl auto-complete	echo "source <(kubectl completion bash)" >> ~/.bashrc
Initialize cluster  verify cluster-info verify kluster + components reset cluster delete tunl0 iface delete pods forcefully deregister a node from the cluster (Unscheduling enabled) Scheduling enabled add a taint to a node remove a taint from a node label a node	kubeadm init --apiserver-advertise-address=MASTERIP --pod-network-cidr=192.168.0.0/16 kubectl cluster-info --minify kubectl version --short && \ kubectl get componentstatus && \ kubectl get nodes --show-labels && \ kubectl cluster-info kubeadm reset -f && rm -rf /etc/kubernetes/ modprobe -r ipip kubectl delete pods --all -n kube-system --grace-period=0 --force kubectl cordon nodeName kubectl drain nodeName  kubectl drain nodeName --ignore-daemonsets --delete-local-data --force kubectl delete node nodeName kubectl uncordon nodeName kubectl taint nodes node01 key1=value1:NoSchedule kubectl taint nodes node01 key1=value1:NoSchedule- kubectl label nodes node01 key=value
setting namespace preference validate current namespace list everything in the cluster	kubectl config set-context --current --namespace=<namespace-name> kubectl config view --minify | grep namespace kubectl get all --all-namespaces
investigate any object investigate kubelet service	kubectl describe node/deployment/svc <objectName> sudo journalctl -u kubelet
exposing deployment as a service patch a svc from ClusterIP to NP port forwarding in svc scaling your deployment use service deployed in other ns	kubectl expose deploy/web --type=NodePort --name=my-svc  kubectl expose deploy/web --port=9443 --target-port=61002 --name=mysvc --type=LoadBalancer kubectl patch svc argocd-server -n argocd -p '{"spec": {"type": "NodePort"}}'  kubectl port-forward svc/my-service -n myNamespace 8080:443 kubectl proxy --port=61000 --address=0.0.0.0 --accept-hosts '.*' & kubectl scale --current-replicas=3 --replicas=4 deployment/my-deployment kubectl scale deployment/my-deployment --replicas=2 -n my-namespace Dns name: <service-name>.<namespace>.svc.cluster.<domain>
all possible attributes of an obj wide details of running pods delete a pod forcefully delete bulk rsrc from a namespace	kubectl explain pod --recursive kubectl get pods -o wide kubectl delete pod mypodName --grace-period=0 --force --namespace myNamespace kubectl delete --all po/podName -n my-namespace
open a bash terminal in a pod  run shell command	kubectl exec -it podName -- bash kubectl exec -it podName -- cat /etc/hosts
create a yaml manifest,  without sending it to the cluster apply a folder of yaml files validate a yaml	kubectl create deploy web --image=nginx --dry-run -o yaml > web.yaml [Imperative way] kubectl apply -R -f . kubectl create --dry-run=client --validate -f file.yaml
create a deployment edit deployment web runtime autoscale deployment  rolling update validate the rollout undo the rollout	kubectl create deploy --image=nginx web --replicas=3 kubectl edit deploy/web kubectl autoscale deploy/web --min=2 --max=5 --cpu-percent=10 kubectl set image deploy/web web=regustry/web:2.0 kubectl rollout status deploy/web kubectl rollout undo deploy/web
passing configmap string passing cm as a properties file   query health check endpoint	kubectl create configmap my-config --from-literal=MESSAGE="hello from configmap” kubectl create cm my-config --from-file=my.properties curl -L http://localhost:8080/healthz
dump logs	kubectl logs podName  kubectl logs podName -c containerName

run kubectl against pods using xargs fetch 1st colmn from o/p of multi pods       refine o/p with specific value

kubectl get pods -o name | xargs -I{} kubectl exec {} -- command  kubectl get pods -n ns | grep -v NAME | sed 's/\|/ /'|awk '{print $1}' kubectl get pods -n ns | grep -v NAME | awk '{print $1}' | cut -c8-14

Calculate max pods in an EC2 instance type

curl -O https://gist.githubusercontent.com/punitporwal07/4dccce3e51503b8fc786d754e64fbe6f/raw/0e4d130db82ee953ce9f93366a35b803cac39faa/max-pods-calculator.sh chmod +x max-pods-calculator.sh aws configure ./max-pods-calculator.sh --instance-type m5.large --cni-version 1.9.0-eksbuild.1