Create and Manage Namespaces Using Declarative Approach¶

Let's see how you can create and manage kubernetes namespaces declaratively.

Step 1: Create a Namespace¶

Let's create two namespaces dev and prod as follows:

1
2
3
4

apiVersion: v1
kind: Namespace
metadata:
  name: dev

1
2
3
4

apiVersion: v1
kind: Namespace
metadata:
  name: prod

Apply the manifest files to create namespaces:

# Create dev namespace
kubectl apply -f dev-namespace.yml

# Create prod namespace
kubectl apply -f prod-namespace.yml

Step 2: List Namespaces¶

List all the namespaces:

kubectl get namespaces

Step 3: Describe a Namespace¶

Describe dev namespace:

kubectl describe namespace dev

Describe prod namespace:

kubectl describe namespace prod

Step 4: Create Kubernetes Resources in a Namespace¶

Let's create two pods. One in dev namespace and another in prod namespace.

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12

apiVersion: v1
kind: Pod
metadata:
  name: dev-pod
  namespace: dev
spec:
  containers:
  - name: nginx
    image: nginx
    imagePullPolicy: Always
    ports:
    - containerPort: 80

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12

apiVersion: v1
kind: Pod
metadata:
  name: prod-pod
  namespace: prod
spec:
  containers:
  - name: nginx
    image: nginx
    imagePullPolicy: Always
    ports:
    - containerPort: 80

Apply the manifest files to create pods:

# Create dev-pod
kubectl apply -f dev-pod.yml

# Create prod-pod
kubectl apply -f prod-pod.yml

Similarly you can create Deployment, ReplicaSet, Service etc. in a namespace. You just have to specify namespace in the metadata section of the resource definition.

Resources will be configured in the default namespace if the namespace field is not set in the metadata section of the resource definition.

Step 5: List Resources in a Namespace¶

List all the pods in the dev namespace:

kubectl get pods -n dev

List all the pods in the prod namespace:

kubectl get pods -n prod

Also, let's start a shell session inside the nginx container of both the pods to verify if the application is running as expected.

1. Verify nginx container of dev-pod in the dev namespace:

   # Start a shell session
   kubectl exec -it dev-pod -n dev -- bash
   
   # Get the default nginx page
   curl localhost
   

2. Verify nginx container of prod-pod in the prod namespace:

   # Start a shell session
   kubectl exec -it prod-pod -n prod -- bash
   
   # Get the default nginx page
   curl localhost
   

Step 6: Delete a Resource in a Namespace¶

Delete dev-pod from dev namespace:

kubectl delete pod dev-pod -n dev
{OR}
kubectl delete -f dev-pod.yml

Delete prod-pod from prod namespace:

kubectl delete pod prod-pod -n prod
{OR}
kubectl delete -f prod-pod.yml

Step 7: Delete a Namespace¶

Delete dev namespace:

kubectl delete ns dev
{OR}
kubectl delete -f dev-namespace.yml

Delete prod namespace:

kubectl delete ns prod
{OR}
kubectl delete -f prod-namespace.yml