Namespace (namespace) of the five major resources of kubernetes

The role of namespaces

The main function is to realize resource isolation of multiple environments or resource isolation of multi-tenants ;

The concept of tenants: when I buy a cloud server, I am its tenant.

By default, all Pods in the kubenetes cluster can access each other , but different Pods may need to be isolated in the actual environment , then different Pods can be divided into different Namespaces .

Kubernetes can form a logical "group" by allocating the resources within the cluster to different Namespaces, so as to facilitate the isolated use and management of resources in different groups

Through the kubernetes authorization mechanism , different Namespaces can be handed over to different tenants for management , thus realizing multi-tenant resource isolation.

Combining the resource quota mechanism of kubernetes in the recording work , limit the resources that different tenants can occupy , such as CPU usage, memory usage, etc., to realize the management of tenants' available resources

That is, even if a resource leak occurs in a pod, it cannot interfere with my underlying resource memory; cpu...

After the cluster is started, kubernetes will create several Namespaces by default.

#View Namespace

[root@master ~]# kubectl get ns 

NAME              STATUS   AGE

default           Active   5d17h

kube-node-lease Active 5d17h #Heartbeat maintenance between cluster nodes , introduced in v1.13

kube-public Active 5d17h #Resources under this namespace can be accessed by everyone, including unauthenticated users

kube-system Active 5d17h #All resources created by the kubernetes system are in this namespace ( when this is running, you need to check whether the pod below is normal; it is normal )

 #All unspecified Namespace objects will be allocated in the default namespace

#View the pod resources in the default space

[root@master ~]# kubectl get pods -n default

NAME                     READY   STATUS    RESTARTS   AGE

nginx-696649f6f9-t4xm6   1/1     Running   0          5d17h

#View pod resources in kube-system space

[root@master ~]# kubectl get pods -n kube-system（系统创建的system空间）

NAME                             READY   STATUS    RESTARTS   AGE

coredns-6955765f44-dzhkh         1/1     Running   0          5d17h

coredns-6955765f44-rn4ds         1/1     Running   0          5d17h

etcd-master                      1/1     Running   0          5d17h

kube-apiserver-master            1/1     Running   0          5d17h

kube-controller-manager-master   1/1     Running   7          5d17h

kube-flannel-ds-2p922            1/1     Running   0          5d17h

kube-flannel-ds-fz8bz            1/1     Running   0          5d17h

kube-flannel-ds-plfvb            1/1     Running   0          5d17h

kube-proxy-7k4lf                 1/1     Running   0          5d17h

kube-proxy-h485n                 1/1     Running   0          5d17h

kube-proxy-m45qq                 1/1     Running   0          5d17h

kube-scheduler-master            1/1     Running   5          5d17h

---

Namespace resource operation command

view command

#View all Namespace information

[root@master ~]# kubectl get ns

NAME              STATUS   AGE

default           Active   5d17h

kube-node-lease   Active   5d17h

kube-public       Active   5d17h

kube-system       Active   5d17h

#View the specified Namespace information

[root@master ~]# kubectl get ns default

NAME      STATUS   AGE

default   Active   5d17h

#View the details of the specified Namespace

[root@master ~]# kubectl describe ns default

Name:         default

Labels:       <none>

Annotations:  <none>

Status: Active # Active indicates that the namespace is in use, and Terminatind indicates that the namespace is being deleted

No resource quota. #Resource limitation for Namespace

No LimitRange resource. #Resource limit for each component in Namespace

This is often configured in work to limit the acquisition of underlying hardware resources.

create command

#Create Namespace

[root@master ~]# kubectl create ns dev

namespace/dev created

#View the specified Namespace

[root@master ~]# kubectl get ns dev

NAME   STATUS   AGE

dev    Active   34s

delete command

#Delete the specified Namespace

[root@master ~]# kubectl delete ns dev

namespace "dev" deleted

Create a Namespace in the form of a configuration file

#Create Namespace through yml file

[root@master ~]# vim ns_dev.yml

apiVersion: v1

kind: Namespace

metadata:

 name: dev

#Create Namspace

[root@master ~]# kubectl create -f ns_dev.yml

#View Namespace

[root@master ~]# kubectl get ns

NAME              STATUS   AGE

default           Active   5d18h

dev               Active   8s

kube-node-lease   Active   5d18h

kube-public       Active   5d18h

kube-system       Active   5d18h

#Delete Namespace

[root@master ~]# kubectl delete -f ns_dev.yml

namespace "dev" deleted

Delete the namespace configured by the yml file; kubectl delete -f ns_dev.yml