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Namespace

Namespaces provide a mechanism for isolating groups of resources within a single cluster. Names of resources need to be unique within a namespace, but not across namespaces. Namespace-based scoping is applicable only for namespaced objects (e.g. Deployments, Services, Pods, etc.) and not for cluster-wide objects (e.g. StorageClass, Nodes, PersistentVolumes, etc.).

By default, a Kubernetes cluster will instantiate a default namespace when provisioning the cluster to hold the default set of Pods, Services, and Deployments used by the cluster.

Create​

To create new namespace we can use kubectl create command or using yaml file definition.

Lets try to create new namespace using command.

➜ kubectl create namespace test  
namespace/test created

We can get list of namespace using kubectl get command.

➜ kubectl get namespace
NAME                   STATUS   AGE
default                Active   28d
kube-node-lease        Active   28d
kube-public            Active   28d
kube-system            Active   28d
kubernetes-dashboard   Active   28d
test                   Active   6s

To delete a namespace we can use kubectl delete command.

➜ kubectl delete namespace test
namespace "test" deleted

Now lets try to create namespace using yaml file definition. This method is preferred if you want to use infrastructure as a code (IaC).

Create new file namespace.yaml and put this namespace definition below. This will create a new namespace named limited.

apiVersion: v1
kind: Namespace
metadata:
  name: limited
  labels:
    name: limited

Lets apply using kubectl apply and get the name space again.

kubectl apply -f namespace.yaml  
namespace/limited created
➜ kubectl get namespace        
NAME                   STATUS   AGE
default                Active   28d
kube-node-lease        Active   28d
kube-public            Active   28d
kube-system            Active   28d
kubernetes-dashboard   Active   28d
limited                Active   10s

References​