Namespace

Basic

# get all namespaces
kubectl get namespaces

# get list of all api resources and if they can/not be namespaced
kubectl api-resources --namespaced=true | head
kubectl api-resources --namespaced=false | head

kubectl describe namespaces

kubectl get pods --all-namespaces

# get all resources all
kubectl get all --all-namespaces

# create namespace with cli
kubectl create namespace playground1

kubectl create namespace Playground1   # will be error

# create namespace with yaml
vagrant@k8s-master:~$ kubectl create namespace demo --dry-run=client -o yaml > demo.yaml
vagrant@k8s-master:~$ more demo.yaml
apiVersion: v1
kind: Namespace
metadata:
  creationTimestamp: null
  name: demo
spec: {}
status: {}
vagrant@k8s-master:~$ kubectl apply -f demo.yaml
namespace/demo created


# delete namespaces
vagrant@k8s-master:~$ kubectl delete namespaces demo
namespace "demo" deleted

Pod with namespace

# get all pod in all namespaces
$ kubectl get pod -A

# get pod in default namespaces
$ kubectl get pods

# get pod in demo namespaces
$ kubectl get pods --namespace=demo

# create a pod in demo namespace
$ kubectl run web --namespace=demo --image=nginx

# or with yaml file
$ more web.yml
apiVersion: v1
kind: Pod
metadata:
  name: web
  namespace: demo
spec:
  containers:
  - image: nginx
    name: web
$ kubectl apply -f web.yml

Change default namespace

vagrant@k8s-master:~$ kubectl create namespace demo
namespace/demo created
vagrant@k8s-master:~$ kubectl run web --namespace demo --image nginx
pod/web created
vagrant@k8s-master:~$ kubectl get pods
No resources found in default namespace.
vagrant@k8s-master:~$ kubectl get pods --namespace demo
NAME   READY   STATUS    RESTARTS   AGE
web    1/1     Running   0          10s

如何切换当前默认的namespace从default到demo

vagrant@k8s-master:~$ kubectl config get-contexts
CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE
*         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin

vagrant@k8s-master:~$ kubectl config set-context --current --namespace demo
Context "kubernetes-admin@kubernetes" modified.
vagrant@k8s-master:~$ kubectl config get-contexts
CURRENT   NAME                          CLUSTER      AUTHINFO           NAMESPACE
*         kubernetes-admin@kubernetes   kubernetes   kubernetes-admin   demo
vagrant@k8s-master:~$ kubectl get pods
NAME   READY   STATUS    RESTARTS   AGE
web    1/1     Running   0          2m44s