Creating a Namespace

Scenario

A namespace is a collection of resources and objects. Multiple namespaces can be created inside a cluster and isolated from each other. This enables namespaces to share the same cluster Services without affecting each other.

For example, you can deploy workloads in a development environment into one namespace, and deploy workloads in a testing environment into another namespace.

Prerequisites

At least one cluster has been created.

Notes and Constraints

A maximum of 6000 Services can be created in each namespace. The Services mentioned here indicate the Kubernetes Service resources added for workloads.

Namespace Types

Namespaces can be created automatically or manually.

• Created automatically: When a cluster is up, the default, kube-public, kube-system, and kube-node-lease namespaces are created by default.
  • default: All objects for which no namespace is specified are allocated to this namespace.
  • kube-public: Resources in this namespace can be accessed by all users (including unauthenticated users) so that some resources in the cluster can be readable in the entire cluster. This is a reserved Kubernetes namespace. Its common attributes are only conventions but not requirements.
  • kube-system: All resources created by Kubernetes are in this namespace.
  • kube-node-lease: Each node has an associated Lease object in this namespace. The object is periodically updated by the node. Both NodeStatus and NodeLease are considered as heartbeats from a node. In versions earlier than v1.13, only NodeStatus is available. The NodeLease feature is introduced in v1.13. NodeLease is more lightweight than NodeStatus. This feature significantly improves the cluster scalability and performance.
• Created manually: You can create namespaces to serve separate purposes. For example, you can create three namespaces, one for a development environment, one for joint debugging environment, and one for test environment. You can also create one namespace for login services and one for game services.

Creating a Namespace

1. Log in to the CCE console and click the cluster name to access the cluster console.
2. Choose Namespaces in the navigation pane and click Create Namespace in the upper right corner.
3. Set namespace parameters based on Table 1.

   Table 1 Parameters for creating a namespace

   Parameter	Description
   Name	Unique name of the created namespace.
   Description	Description about the namespace.
   Quota Management	Resource quotas can limit the amount of resources available in namespaces, achieving resource allocation by namespace. NOTICE: You are advised to set resource quotas in the namespace as required to prevent cluster or node exceptions caused by resource overload. For example, the default number of pods that can be created on each node in a cluster is 110. If you create a cluster with 50 nodes, you can create a maximum of 5,500 pods. Therefore, you can set a resource quota to ensure that the total number of pods in all namespaces does not exceed 5,500. Enter an integer. If the quota of a resource is not specified, no limit is posed on the resource. If you want to limit the CPU or memory quota, you must specify the CPU or memory request value when creating a workload.

4. After the configuration is complete, click OK.

Using kubectl to Create a Namespace

Define a namespace.

apiVersion: v1 
kind: Namespace 
metadata: 
  name: custom-namespace 

Run the kubectl command to create it.

$ kubectl create -f custom-namespace.yaml
namespace/custom-namespace created 

You can also run the kubectl create namespace command to create a namespace.

$ kubectl create namespace custom-namespace 
namespace/custom-namespace created