Kubernetes Cheat Sheet
15 Oct 2018 -
Shyam Mohan
Kubernetes is an open-source container-orchestration system for automating application deployment, scaling, and management. It was originally designed by Google, and is now maintained by the Cloud Native Computing Foundation.
Common Commands
Name
Command
Run curl test temporarily
kubectl run --rm mytest --image=yauritux/busybox-curl -it
Run wget test temporarily
kubectl run --rm mytest --image=busybox -it
Run nginx deployment with 2 replicas
kubectl run my-nginx --image=nginx --replicas=2 --port=80
Run nginx pod and expose it
kubectl run my-nginx --restart=Never --image=nginx --port=80 --expose
Run nginx deployment and expose it
kubectl run my-nginx --image=nginx --port=80 --expose
Set namespace preference
kubectl config set-context <context_name> --namespace=<ns_name>
List pods with nodes info
kubectl get pod -o wide
List everything
kubectl get all --all-namespaces
Get all services
kubectl get service --all-namespaces
Show nodes with labels
kubectl get nodes --show-labels
Validate yaml file with dry run
kubectl create --dry-run --validate -f pod-dummy.yaml
Start a temporary pod for testing
kubectl run --rm -i -t --image=alpine test-$RANDOM -- sh
kubectl run shell command
kubectl exec -it mytest -- ls -l /etc/hosts
Get system conf via configmap
kubectl -n kube-system get cm kubeadm-config -o yaml
Get deployment yaml
kubectl -n denny-websites get deployment mysql -o yaml
Explain resource
kubectl explain pods, kubectl explain svc
Watch pods
kubectl get pods -n wordpress --watch
Query healthcheck endpoint
curl -L https://127.0.0.1:10250/healthz
Open a bash terminal in a pod
kubectl exec -it storage sh
Check pod environment variables
kubectl exec redis-master-ft9ex env
Enable kubectl shell autocompletion
echo "source <(kubectl completion bash)" >>~/.bashrc, and reload
Use minikube dockerd in your laptop
eval $(minikube docker-env), No need to push docker hub any more
Kubectl apply a folder of yaml files
kubectl apply -R -f .
Get services sorted by name
kubectl get services –sort-by=.metadata.name
Get pods sorted by restart count
kubectl get pods –sort-by=’.status.containerStatuses[0].restartCount’
Ubuntu install kubectl "deb https://apt.kubernetes.io/ kubernetes-xenial main"
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Check Performance
Name
Command
Get node resource usage
kubectl top node
Get pod resource usage
kubectl top pod
Get resource usage for a given pod
kubectl top <podname> --containers
List resource utilization for all containers
kubectl top pod --all-namespaces --containers=true
Resources Deletion
Name
Command
Delete pod
kubectl delete pod/<pod-name> -n <my-namespace>
Delete pod by force
kubectl delete pod/<pod-name> --grace-period=0 --force
Delete pods by labels
kubectl delete pod -l env=test
Delete deployments by labels
kubectl delete deployment -l app=wordpress
Delete all resources filtered by labels
kubectl delete pods,services -l name=myLabel
Delete resources under a namespace
kubectl -n my-ns delete po,svc --all
Delete persist volumes by labels
kubectl delete pvc -l app=wordpress
Delete statefulset only (not pods)
kubectl delete sts/<stateful_set_name> --cascade=false
Log & Conf Files
Name
Comment
Config folder
/etc/kubernetes/
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/
log in worker node
/var/log/kubelet.log, /var/log/kube-proxy.log
log in master node
kube-apiserver.log, kube-scheduler.log, kube-controller-manager.log
Env
/etc/systemd/system/kubelet.service.d/10-kubeadm.conf
Env
export KUBECONFIG=/etc/kubernetes/admin.conf
Pod
Name
Command
List all pods
kubectl get pods
List pods for all namespace
kubectl get pods -all-namespaces
List all critical pods
kubectl get -n kube-system pods -a
List pods with more info
kubectl get pod -o wide, kubectl get pod/<pod-name> -o yaml
Get pod info
kubectl describe pod/srv-mysql-server
List all pods with labels
kubectl get pods --show-labels
List running pods
kubectl get pods –field-selector=status.phase=Running
Get Pod initContainer status
kubectl get pod --template '{.status.initContainerStatuses}' <pod-name>
kubectl run command
kubectl exec -it -n “$ns” “$podname” – sh -c “echo $msg >>/dev/err.log”
Watch pods
kubectl get pods -n wordpress --watch
Get pod by selector
kubectl get pods –selector=”app=syslog” -o jsonpath='{.items[*].metadata.name}’
List pods and images
kubectl get pods -o=’custom-columns=PODS:.metadata.name,Images:.spec.containers[*].image’
List pods and containers
-o=’custom-columns=PODS:.metadata.name,CONTAINERS:.spec.containers[*].name’
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Label & Annontation
Name
Command
Filter pods by label
kubectl get pods -l owner=denny
Manually add label to a pod
kubectl label pods dummy-input owner=denny
Remove label
kubectl label pods dummy-input owner-
Manually add annonation to a pod
kubectl annotate pods dummy-input my-url=https://dennyzhang.com
Deployment & Scale
Name
Command
Scale out
kubectl scale --replicas=3 deployment/nginx-app
online rolling upgrade
kubectl rollout app-v1 app-v2 --image=img:v2
Roll backup
kubectl rollout app-v1 app-v2 --rollback
List rollout
kubectl get rs
Check update status
kubectl rollout status deployment/nginx-app
Check update history
kubectl rollout history deployment/nginx-app
Pause/Resume
kubectl rollout pause deployment/nginx-deployment, resume
Rollback to previous version
kubectl rollout undo deployment/nginx-deployment
Quota & Limits & Resource
Name
Command
List Resource Quota
kubectl get resourcequota
List Limit Range
kubectl get limitrange
Customize resource definition
kubectl set resources deployment nginx -c=nginx --limits=cpu=200m
Customize resource definition
kubectl set resources deployment nginx -c=nginx --limits=memory=512Mi
Service
Name
Command
List all services
kubectl get services
List service endpoints
kubectl get endpoints
Get service detail
kubectl get service nginx-service -o yaml
Get service cluster ip
kubectl get service nginx-service -o go-template='{.spec.clusterIP}’
Get service cluster port
kubectl get service nginx-service -o go-template='{(index .spec.ports 0).port}’
Expose deployment as lb service
kubectl expose deployment/my-app --type=LoadBalancer --name=my-service
Expose service as lb service
kubectl expose service/wordpress-1-svc --type=LoadBalancer --name=ns1
Secrets
Name
Command
List secrets
kubectl get secrets --all-namespaces
Generate secret
echo -n 'mypasswd', then redirect to base64 -decode
Create secret from cfg file
kubectl create secret generic db-user-pass –from-file=./username.txt
StatefulSet
Name
Command
List statefulset
kubectl get sts
Delete statefulset only (not pods)
kubectl delete sts/<stateful_set_name> --cascade=false
Scale statefulset
kubectl scale sts/<stateful_set_name> --replicas=5
Volumes & Volume Claims
Name
Command
List storage class
kubectl get storageclass
Check the mounted volumes
kubectl exec storage ls /data
Check persist volume
kubectl describe pv/pv0001
Copy local file to pod
kubectl cp /tmp/my <some-namespace>/<some-pod>:/tmp/server
Copy pod file to local
kubectl cp <some-namespace>/<some-pod>:/tmp/server /tmp/my
Events & Metrics
Name
Command
View all events
kubectl get events --all-namespaces
List Events sorted by timestamp
kubectl get events –sort-by=.metadata.creationTimestamp
Node Maintenance
Name
Command
Mark node as unschedulable
kubectl cordon $NDOE_NAME
Mark node as schedulable
kubectl uncordon $NDOE_NAME
Drain node in preparation for maintenance
kubectl drain $NODE_NAME
Namespace & Security
Name
Command
List authenticated contexts
kubectl config get-contexts, ~/.kube/config
Set namespace preference
kubectl config set-context <context_name> --namespace=<ns_name>
Load context from config file
kubectl get cs --kubeconfig kube_config.yml
Switch context
kubectl config use-context <cluster-name>
Delete the specified context
kubectl config delete-context <cluster-name>
List all namespaces defined
kubectl get namespaces
List certificates
kubectl get csr
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Network
Name
Command
Temporarily add a port-forwarding
kubectl port-forward redis-izl09 6379
Add port-forwaring for deployment
kubectl port-forward deployment/redis-master 6379:6379
Add port-forwaring for replicaset
kubectl port-forward rs/redis-master 6379:6379
Add port-forwaring for service
kubectl port-forward svc/redis-master 6379:6379
Get network policy
kubectl get NetworkPolicy
Patch
Name
Summary
Patch service to loadbalancer
kubectl patch svc $svc_name -p '{"spec": {"type": "LoadBalancer"}}'
Extenstions
Name
Summary
List api group
kubectl api-versions
List all CRD
kubectl get crd
List storageclass
kubectl get storageclass
List all supported resources
kubectl api-resources
Components & Services
1. Services on Master Nodes
Name
Summary
kube-apiserver exposes the Kubernetes API from master nodes
etcd reliable data store for all k8s cluster data
kube-scheduler schedule pods to run on selected nodes
kube-controller-manager node controller, replication controller, endpoints controller, and service account & token controllers
2. Services on Worker Nodes
3. Addons: pods and services that implement cluster features
Name
Summary
DNS
serves DNS records for Kubernetes services
Web UI
a general purpose, web-based UI for Kubernetes clusters
Container Resource Monitoring
collect, store and serve container metrics
Cluster-level Logging
save container logs to a central log store with search/browsing interface
