K8S¶
Help¶
kubectl --help
kubectl get nodes --help
Top kubectl commands¶
- use on node, pods, deployments
kubectl get
kubectl get -o wide
kubectl describe
kubectl logs
kubectl exec
kubectl exec -ti
Start with Minikube¶
minikube version
minikube start
minikube ip
kubectl version
kubectl cluster-info
kubectl get nodes
start minikube
# from start.sh for https://kubernetes.io/docs/tutorials/hello-minikube/
minikube version
minikube start --wait=false
minikube addons enable dashboard
kubectl apply -f /opt/kubernetes-dashboard.yaml
minikube status
Deployment¶
# view config
kubectl config view
# open dashboard
minikube dashboard
## create a deployment
# add `--expose` to create a service at the same time
kubectl create deployment <some-name> --image=<some-image>
# view deployments
kubectl get deployments
# view pods
kubectl get pods
# view events
kubectl get events
# view services
kubectl get services
# view pod and services
kubectl get pod,svc -n kube-system
# view with template
kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}'
Service¶
Service Types (in ServiceSpec)
- ClusterIP (default)
- NodePort
- LoadBalancer
- ExternalName (1.7 or higher of
kube-dns)
# expose (create) Service outside of the cluster
kubectl expose deployment hello-node --type=LoadBalancer --port=8080
kubectl expose deployment/hello --type="NodePort" --port=8080
## LoadBalancer type makes Services in minikube accessible via:
## minikube service <some-service>
# get NodePort (output has no newline)
kubectl get services/<some-service> -o go-template='{{(index .spec.ports 0).nodePort}}'
kubectl get svc <some-service> -o go-template='{{(index .spec.ports 0).nodePort}}'
Proxy¶
# forward communication to in-cluster private network
# ctrl-C to stop
kubectl proxy
# get proxy node name via:
kubectl get pods -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}'
# node will be accessible via route:
http://localhost:8001/api/v1/namespaces/default/pods/$POD_NAME/proxy/
Addons¶
# currently supported addons
minikube addons list
minikube addons enable <some-addon>
minikube addons disable <some-addon>
Delete¶
kubectl delete service <some-service>
kubectl delete service -l <some-service-label>
kubectl delete deployment <some-deployment>
# stop minikube VM
minikube stop
# delete minikube VM
minikube delete
Exec¶
kubectl exec <some-pod-name> env
kubectl exec -ti <some-pod-name> bash
Labels¶
Query
# example way to get labels of deployments
kubectl describe deployment
# query list of Pods
kubectl get pods -l <some-label>
Change
kubectl label pod <some-pod-name> app=v0
Scale¶
# set 0 to remove all replicas
kubectl scale deployment <some-deployment> --replicas=4
Update¶
kubectl set image --help
kubectl set image deployments <some-resource> <some-container>=<some-target-container-image>:v2
# check rollout status
kubectl rollout status <some-resource>
# rollback
kubectl rollout undo <some-resource>