Kubernetes - Namespaces

tags: Kubernetes

Foreword

When the objects of cluster and people using Kubernetes cluster are increasing, we can use the Namespaces to manage our project.

Namespaces

Definition

Kubernetes supports multiple virtual clusters backed by the same physical cluster. These virtual clusters are called namespaces. Namespaces are a way to divide cluster resources between multiple user.

Features

• In the same kubernetes cluster all of namespaces are unique.
• When we delete the namespaces, the object of namespace will be deleted in the same time.
• We can use the Resource Quotas to limit the resource of the object in that Namespace.

Practice

We can use kubectl get namespaces to see the all namespaces on the kubernetes cluster.

• default When you create the object, you don’t set the namespace the namespaces of object will be default.
• kube-system The namespace for objects created by the Kubernetes system.
• kube-public This namespace is created automatically and is readable by all users.

We can use kubectl create namespace <namespace_name> to create a new namespace.

We also can use kubectl delete namespaces <namespace_name> to delete namespaces.

Recourse Quotas

Use the follow yaml file to create a Namespace and Resource Quotas.

apiVersion: v1
kind: Namespace
metadata:
  name: hello-space
---
apiVersion: v1
kind: ResourceQuota
metadata:
  name: compute-quotas
  namespace: hello-space
spec:
  hard:
    requests.cpu: "1"
    requests.memory: 1Gi
    limits.cpu: "2"
    limits.memory: 10Gi
---
apiVersion: v1
kind: ResourceQuota
metadata:
  name: object-quotas
  namespace: hello-space
spec:
  hard:
    services: "2"
    services.loadbalancers: "1"
    secrets: "1"
    configmaps: "1"
    replicationcontrollers: "10"

In this yaml we create a “hellospace” namespace.

• compute-quotas Limit the resource of cpu and memory.
• object-quotas Limit the namespace can only has two services, and one loadbalancer, secret, and configmap.

Reference

https://ithelp.ithome.com.tw/articles/10197186

https://kubernetes.io/docs/concepts/overview/working-with-objects/namespaces/

https://kubernetes.io/docs/concepts/policy/resource-quotas/