vladwa/kuberenetes-kubectl-cheatsheet

Kubernetes or Kubectl cheatsheet.

Kubernetes kubectl cheatsheet

Kubernetes Components

Control Plane Components (Master Nodes)

Component Name	Summary	Runs As
kube-apiserver	Exposes the Kubernetes API from master nodes.The API server is the front end for the Kubernetes control plane. Can run several instances of kube-apiserver and balance traffic between those instances	Static Pod
etcd	Consistent and highly-available key value store used as Kubernetes’ backing store for all cluster data	Static Pod or Systemd service
kube-scheduler	Component that watches for newly created Pods with no assigned node, and selects a node for them to run on	Static Pod
kube-controller-manager	Component that runs controller processesnode. Controllers include : Node Controller, Replication Controller, Endpoints Controller, Service Account & Token Controllers	Static Pod

Node Components(Worker Nodes)

Component Name	Summary	Runs As
kubelet	An agent that runs on each node in the cluster. It makes sure that containers are running in a Pod	System process
kube-proxy	kube-proxy is a network proxy that runs on each node in your cluster, implementing part of the Kubernetes Service concept	Daemonset
Container Runtime	Is the software that is responsible for running containers. Kubernetes supported runtimes: Docker, rkt, runc and any [[https://github.com/opencontainers/runtime-spec][OCI runtime-spec]] implementation	Systemd service

Master and Worker nodes ports

Generators

You can create the following resources using kubectl run with the --generator flag

Resource	api group	kubectl command
Pod	v1	kubectl run --generator=run-pod/v1
Replication controller (deprecated)	v1	kubectl run --generator=run/v1
Deployment (deprecated)	apps/v1beta1	kubectl run --generator=deployment/apps.v1beta1
Job (deprecated)	batch/v1	kubectl run --generator=job/v1
CronJob (deprecated)	batch/v1beta1	kubectl run --generator=cronjob/v1beta1
CronJob (deprecated)	batch/v2alpha1	kubectl run --generator=cronjob/v2alpha1

Configuration and Logs details of Kubernetes,Docker

Description	Folder or File location
Config folder	/etc/kubernetes/
Manifests dir	/etc/kubernetes/manifests
Certificate files	/etc/kubernetes/pki/
Credentials to API server	/etc/kubernetes/kubelet.conf
Superuser credentials	/etc/kubernetes/admin.conf
kubectl config file	~/.kube/config
Kubernets working dir	/var/lib/kubelet/
Docker working dir	/var/lib/docker/, /var/log/containers/
Etcd working dir	/var/lib/etcd/
Network cni	/etc/cni/net.d/
Log files	/var/log/pods/
Kubelet logs	/var/log/messages, /var/log/pods/kube-system_kube-proxy*/kube-proxy/*.log
Kube-proxy	/var/log/pods/kube-system_kube-proxy*/kube-proxy/*.log
Kube-api-server	/var/log/pods/kube-system_kube-apiserver*/kube-proxy/*.log
Kube-controller	/var/log/pods/kube-system_kube-controller*/kube-proxy/*.log
Kube-scheduller	/var/log/pods/kube-system_kube-scheduler*/kube-scheduler/*.log
Env	/etc/systemd/system/kubelet.service.d/10-kubeadm.conf
Env	export KUBECONFIG=/etc/kubernetes/admin.conf
Audit logs	/var/log/audit/audit.log
Kubelet env file	/etc/kubernetes/kubelet.env
kubelet.service	/etc/systemd/system/kubelet.service
docker.service	/etc/systemd/system/docker.service

Check health of cluster

Description	command
Check cluster health	kubectl get componentstatus
Check etcd health	kubectl get --raw=/healthz/etcd

Kubelet and Docker commands

Description	Command or File location
Check Kubelet status	service kubelet status or systemctl status kubelet.service
Restart Kubelet	service kubelet restart or systemctl restart kubelet.service
Stop Kubelet	service kubelet stop or systemctl stop kubelet.service
Tail Kubelet logs	journalctl -u kubelet.service -f
Check Docker daemon status	service docker status or systemctl status docker.service
Restart Docker daemon	service docker restart or systemctl restart docker.service
Stop Docker daemon	service docker stop or systemctl stop docker.service
Tail Docker daemon logs	journalctl -u docker.service -f

Kubernetes networking commands

Description	Command
List interfaces on the host	ip link
Lists IP address assigned to the interfaces	ip addr
View the routing table	ip route
Add the entries to the routing table	ip route add 192.168.1.0/24 via 192.168.2.1
Enable ipv4 forwarding	echo 1 > /proc/sys/net/ipv4/ip_forward
Enable ipv6 forwarding	echo 1 > /proc/sys/net/ipv6/ip_forward
list network namespaces	ip netns
Adding blue namespace	ip netns add blue
Exec to the particular namesapce	ip netns exec NAMESPACE_NAME ip link or ip -n red link

Kubernetes cluster upgrade kubeadm way

Description	Command
Install kubeadm new version	apt-get upgrade -y kubeadm=1.19.0-00
Upgrade plan	kubeadm upgarade plan v1.19.0
Apply upgrade plan	kubeadm upgrade apply v1.19.0
Update kubelet	apt-get upgrade kubelet=1.19.0-00
Update kubelet configuration	kubeadm upgarde node config --kubelet-version v1.19.0
Restart kubelet	systemctl restart kubelet

ETCD Backup & Restore

Description	Command
ETCD Backup	ETCDCTL_API=3 etcdctl --endpoints=https://127.0.0.1:2379 --cacert="/etc/kubernetes/pki/etcd/server.crt" --cert="/etc/kubernetes/pki/etcd/ca.crt" --key="/etc/kubernetes/pki/etcd/ca.key" snapshot save /tmp/snapshot-pre-boot.db
ETCD Restore	ETCDCTL_API=3 etcdctl --endpoints=https://[127.0.0.1]:2379 --cacert=/etc/kubernetes/pki/etcd/ca.crt --name=master --cert=/etc/kubernetes/pki/etcd/server.crt --key=/etc/kubernetes/pki/etcd/server.key --data-dir /var/lib/etcd-from-backup --initial-cluster=master=https://127.0.0.1:2380 --initial-cluster-token etcd-cluster-1 --initial-advertise-peer-urls=https://127.0.0.1:2380 snapshot restore /tmp/snapshot-pre-boot.db

Pod

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
pods	po	-	true	Pod	[create delete deletecollection get list patch update watch]

Description	Kubectl Command
Create	kubectl run nginx --generator=run-pod/v1 --image=nginx
Create in particular namespace	kubectl run nginx --generator=run-pod/v1 --image=nginx -n NAMEPSPACE
Dry run,print object without creating it	kubectl run POD_NAME --generator=run-pod/v1 --image=nginx --dry-run -o yaml
Create from File	kubectl create -f pod.yaml
Create from File in particular namespace	kubectl create -f pod.yaml -n NAMEPSPACE
List pods	kubectl get po or kubectl get pod or kubectl get pods
List pods in all namespaces	kubectl get pods --all-namespaces or kubectl get pods -A
List pods with more information	kubectl get pods -owide
List pods information in custom columns	kubectl get pod POD_NAME -o custom-columns=CONTAINER:.spec.containers[0].name,IMAGE:.spec.containers[0].image
Verbose Debug information/describe pod	kubectl describe pod POD_NAME
Logs	kubectl logs POD_NAME
Logs (multi-container case)	kubectl logs POD_NAME -c CONTAINER_NAME
Tail pod logs	kubectl logs -f POD_NAME
Tail pods logs (multi-container case)	kubectl logs -f POD_NAME -c CONTAINER_NAME
Delete pod	kubectl delete pod POD_NAME or kubectl delete -f pod.yaml or kubectl delete pod/POD_NAME
Delete pod in particular namespace	kubectl delete pod POD_NAME -n NAMESPACE
Delete pod forcefully	kubectl delete pod my-pod --grace-period=0 --force
Get pod	kubectl get pod POD_NAME
Watch pod	kubectl get pod POD_NAME --watch
Patch pod	kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname"}]}}'
Create and wrtie its spec to file	kubectl run POD_NAME --image=nginx --restart=Never --dry-run -o yaml > pod.yaml
List pod in Json output format	kubectl get pods -o json
List pod in YAML output format	kubectl get pods -o yaml
Run command in existing pod	kubectl exec POD_NAME -- ls /
Run command in existing pod (multi-container case)	kubectl exec POD_NAME -c CONTAINER_NAME -- ls /
Exec to pod	kubectl exec -it POD_NAME bash
List Kubernetes critical pods	kubectl get pods -n kube-system

ReplicaSet

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
replicasets	rs	apps,extensions	true	ReplicaSet	[create delete deletecollection get list patch update watch]

Verb Description	Kubectl Command
create	kubectl create -f replicaset.yaml
List	kubectl get rs or kubectl get replicaset or kubectl get replicasets
List replicasets with more information	kubectl get rs -owide
List in all namespaces	kubectl get rs --all-namespaces or kubectl get rs -A
Delete	kubectl delete rs REPLICASET_NAME or kubectl delete -f replicaset.yaml
Get	kubectl get rs REPLICASET_NAME

Deployments,Scale,Rolling Updates & Rollbacks

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
deployments	deploy	apps,extensions	true	Deployment	[create delete deletecollection get list patch update watch]

Verb Description	Kubectl Command
Deployment Strategy Types	Rolling-Update or Recreate
Create Deployment	kubectl create deployment DEPLOYMENT_NAME --image=busybox
Run deployment with 2 replicas	kubectl run POD_NAME --image=nginx --replicas=2 --port=80
List deployments	kubectl get deploy or kubectl get deployment or kubectl get deployments
List deployments in all namespaces	kubectl get deploy --all-namespaces or kubectl get deploy -A
List deployments in particular namespace	kubectl get deploy -n NAMESPACE
List deployments with more information	kubectl get deploy -owide
Delete deployment	kubectl delete deploy DEPLOYMENT_NAME or kubectl delete -f deployment.yaml
Get particular deployment	kubectl get deploy DEPLOYMENT_NAME
Run deployment and expose it	kubectl run DEPLOYMENT_NAME --image=nginx --port=80 --expose
Update the nginx Pods to use the nginx:1.9.1 image instead of the nginx:1.7.9 image	kubectl set image deployment/nginx-deployment nginx=nginx:1.9.1 --record
Edit the Deployment	kubectl edit deploy/DEPLOYMENT_NAME
Deployment rollout status	kubectl rollout status deploy/DEPLOYMENT_NAME
Deployment rollout history	kubectl rollout history deploy/DEPLOYMENT_NAME
Rolling back deployment to previous version	kubectl rollout undo deploy/DEPLOYMENT_NAME
Scaling deployment	kubectl scale --replicas=2 deploy/DEPLOYMENT_NAME
Pausing deployment	kubectl rollout pause deploy/DEPLOYMENT_NAME
Resuming deployment	kubectl rollout resume deploy/DEPLOYMENT_NAME
Verbose Debug information/describe deployment	kubectl describe deploy/DEPLOYMENT_NAME
Describe all deployments	kubectl describe deployments
Watch deployment	kubectl get deploy/DEPLOYMENT_NAME --watch

DaemonSet

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
daemonsets	ds	apps,extensions	true	DaemonSet	[create delete deletecollection get list patch update watch]

Verb Description	Kubectl Command
List daemonsets	kubectl get ds or kubectl get daemonset or kubectl get daemonset
List daemonsets in all namespaces	kubectl get ds --all-namespaces or kubectl get ds -A
List daemonsets with more information	kubectl get ds -owide
Delete	kubectl delete ds DAEMONSET_NAME or kubectl delete -f daemonset.yaml
Get particular daemonset	kubectl get ds DAEMONSET_NAME
Verbose Debug information/describe Daemonset	kubectl describe ds/DAEMONSET_NAME

Jobs

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
jobs	-	batch	true	Job	[create delete deletecollection get list patch update watch]

Verb Description	Kubectl Command
Create	kubectl create job my-job --image=busybox
Create a job with command	kubectl create job my-job --image=busybox -- date
Create a job from a CronJob named "a-cronjob"	kubectl create job test-job --from=cronjob/a-cronjob
List jobs	kubectl get jobs or kubectl get job
List jobs in all namespaces	kubectl get jobs --all-namespaces or kubectl get jobs -A
List with more information	kubectl get job -owide
Delete	kubectl delete jobs JOB_NAME or kubectl delete -f job.yaml
Get particular cronjob	kubectl get cj cronjob_NAME
Verbose Debug information/describe job	kubectl describe jobs/CRRONJOB_NAME

CronJob

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
cronjobs	cj	batch	true	CronJob	[create delete deletecollection get list patch update watch]

Verb Description	Kubectl Command
Create with schedule	kubectl create cronjob CRONJOB_NAME --image=busybox --schedule="*/1 * * * *"
List	kubectl get cj or kubectl get cronjob or kubectl get cronjobs
List in all namespaces	kubectl get cj --all-namespaces or kubectl get cj -A
List with more information	kubectl get cj -owide
Delete	kubectl delete cj CRONJOB_NAME or kubectl delete -f cronjob.yaml
Get particular cronjob	kubectl get cj cronjob_NAME
Verbose Debug information/describe cronjob	kubectl describe cj/CRRONJOB_NAME

Service

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
services	svc	-	true	Service	[create delete get list patch update watch]

Service Type	Description	Kubectl Command
ClusterIP	Create service	kubectl create service clusterip my-cs --tcp=5678:8080
	Create service in headless mode	kubectl create service clusterip my-cs --clusterip="None"
ExternalName	Create an ExternalName service	kubectl create service externalname my-ns --external-name example.com
LoadBalancer	Create a LoadBalancer service	kubectl create service loadbalancer my-lbs --tcp=5678:8080
NodePort	Create a NodePort service	kubectl create service nodeport my-ns --tcp=5678:8080

Verb Description	Kubectl Command
List	kubectl get service or kubectl get svc
List in all namespaces	kubectl get service --all-namespaces or kubectl get svc -A
List with more information	kubectl get svc -owide or kubectl get service -owide
Delete	kubectl delete svc SERVICE_NAME or kubectl delete -f service.yaml
Get particular service	kubectl get service SERVICE_NAME
Verbose Debug information/describe service	kubectl describe svc/SERVICE_NAME

Namespace

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
namespaces	ns	-	false	Namespace	[create delete get list patch update watch]

Verb Description	Kubectl Command
List	kubectl get namespaces or kubectl get ns
Create	kubectl create ns TEST
Delete	kubectl delete ns TEST or kubectl delete -f namespace.yaml
Get particular namespace	kubectl get ns TEST
Verbose Debug information/describe service	kubectl describe ns/TEST

Serviceaccounts

NAME	SHORTNAMES	APIGROUP	NAMESPACED	KIND	VERBS
serviceaccounts	sa	-	true	ServiceAccount	[create delete deletecollection get list patch update watch]

Verb Description	Kubectl Command
List	kubectl get sa
Create	kubectl create serviceaccount my-service-account
Delete	kubectl delete serviceaccount my-service-account or kubectl delete -f my-service-account.yaml
Get particular sa	kubectl get sa my-service-account
Verbose Debug information/describe service	kubectl describe sa/my-service-account

Node Maintenance

Description	Command
Mark node as unschedulable	kubectl cordon $NODE_NAME
Mark node as schedulable	kubectl uncordon $NODE_NAME
Drain node in preparation for maintenance	kubectl drain $NODE_NAME
Drain node with grace period of 15 mins	kubectl drain $NODE_NAME --grace-period=900
Drain node forcefully	kubectl drain $NODE_NAME --force
Ignore DaemonSet-managed pods while draining node	kubectl drain $NODE_NAME --grace-period=900 --ignore-daemonsets=true

Events

Description	Command
View all events	kubectl get events --all-namespaces or kubectl get events -A
List Events sorted by timestamp	kubectl get events --sort-by=.metadata.creationTimestamp
List Events only in kube-system namespace	kubectl get events -n kube-system