命名空间的出现，原理上是为了划分组的方式来管理pod在哪个namespace上运行，而不需要去关心这些pod具体在哪个节点上工作，就好像QQ群一样。

查看ns

[root@master ~]# kubectl get ns       
NAME              STATUS   AGE
default           Active   166m
kube-node-lease   Active   166m
kube-public       Active   166m
kube-system       Active   166m

新建一个ns

[root@master ~]# kubectl create ns ns1
namespace/ns1 created
[root@master ~]# kubectl get ns       
NAME              STATUS   AGE
default           Active   166m
kube-node-lease   Active   166m
kube-public       Active   166m
kube-system       Active   166m
ns1               Active   1s

删除一个命名空间

[root@master ~]# kubectl delete ns ns1
namespace "ns1" deleted

如果删不掉ns1就需要特别处理

kubectl delete ns ns1 #先用delete删除
kubectl proxy --port=8081 #单独开一个终端，做api代理
#下面通过强制删除ns1
kubectl get ns ns1 -o json | jq 'del(.spec.finalizers)' |curl -v -H "Content-Type: application/json"  -X PUT --data-binary @- http://127.0.0.1:8081/api/v1/namespaces/ns1/finalize
[root@master ~]#kubectl get ns
NAME              STATUS   AGE
default           Active   3h24m
kube-node-lease   Active   3h24m
kube-public       Active   3h24m
kube-system       Active   3h24m
#这样就删除干净了

没有jq的话，可以按照如下方式安装jq

wget http://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
rpm -ivh epel-release-latest-7.noarch.rpm
yum repolist
yum install -y jq

namespace快速切换器kubectx的安装

git clone https://github.com/ahmetb/kubectx.git
cp kubectx/kube* /usr/local/bin/ ##把相关文件放到可执行目录里

[root@master kubectx-master]# kubens 
default
kube-node-lease
kube-public
kube-system
ns1

[root@master kubectx-master]# kubens --help
USAGE:
  kubens                    : list the namespaces in the current context  #list namespace
  kubens <NAME>             : change the active namespace of current context   #切换namespace
  kubens -                  : switch to the previous namespace in this context  #切到原来的
  kubens -c, --current      : show the current namespace #显示当前namespace
  kubens -h,--help          : show this message
[root@master kubectx-master]# kubens ns1
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "ns1".
[root@master kubectx-master]# kubens 
default
kube-node-lease
kube-public
kube-system
ns1
[root@master kubectx-master]# kubens -c
ns1

[root@master kubectx-master]# kubectl config set-context --current --namespace=ns1  #还可以原生的切换
Context "kubernetes-admin@kubernetes" modified.
[root@master kubectx-master]# kubens -   #查看之前的namespace
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "ns1".
[root@master kubectx-master]# kubens -
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "ns1".
[root@master kubectx-master]# kubens -c #查看当前的namespace
ns1
[root@master kubectx-master]# kubectl get pods #查当前的namespace下有什么资源
No resources found in ns1 namespace.
[root@master kubectx-master]# kubens  #查看所有的namespace
default
kube-node-lease
kube-public
kube-system
ns1
[root@master kubectx-master]# kubens default   #切换回default
Context "kubernetes-admin@kubernetes" modified.
Active namespace is "default".
[root@master kubectx-master]# kubectl get pods #查当前的namespace下有什么资源，发现有了原来的资源了
NAME                               READY   STATUS    RESTARTS   AGE
nginx-deployment-c7c9d97b4-7vdrh   1/1     Running   0          103m
nginx-deployment-c7c9d97b4-gcn4f   1/1     Running   0          78m