Namespaces provide a scope for Kubernetes resources, carving up your cluster in smaller units.
You can think of it as a workspace you’re sharing with other users. Many resources such as pods and services are namespaced. Others, such as nodes, are not namespaced, but are instead treated as cluster-wide.
As a developer, you’ll usually use an assigned namespace, however admins may wish to manage them, for example to set up access control or resource quotas.
Like other resources, the
get subcommand displays a list of all namespaces a user has access to in a cluster (both the full resource type name
namespace and the abbreviation
ns can be used):
$ kubectl get ns
On a simple
minikube installation, the result shows:
NAME STATUS AGE default Active 17h kube-node-lease Active 17h kube-public Active 17h kube-system Active 17h
You can learn more about a namespace using the
$ kubectl describe ns default
If no changes were made to the minikube cluster, the output should look like the following:
Name: default Labels: <none> Annotations: <none> Status: Active No resource quota. No LimitRange resource.
Let’s now create a new namespace called
$ kubectl apply -f https://github.com/openshift-evangelists/kbe/raw/main/specs/ns/ns.yaml
Once the namespace is created, it will appear in the list of available namespaces:
$ kubectl get ns
Alternatively, we could have created the namespace using the
kubectl create namespace test command.
To launch a pod in the newly created namespace test, run:
$ kubectl apply --namespace=test -f https://github.com/openshift-evangelists/kbe/raw/main/specs/ns/pod.yaml
Note that using above method the namespace becomes a runtime property.
In other words, you can deploy the same pod or service into multiple namespaces (for example, dev and prod).
Hard-coding the namespace directly in the
metadata section as shown in the following is possible, but causes less flexibility when deploying your apps:
apiVersion: v1 kind: Pod metadata: name: podintest namespace: test
To list namespaced objects, such as our pod
podintest, pass the
--namespace variable to the get call:
$ kubectl get pods --namespace=test
You can remove the namespace (and everything inside of it) with:
$ kubectl delete ns test
If you’re an admin, you might want to check out the docs for more info how to handle namespaces.