Namespaces in Kubernetes are a way to divide cluster resources between multiple users. They provide a mechanism for isolating groups of resources within a single cluster. Namespaces are intended for use in environments with many users spread across multiple teams, or projects.

• Isolation: Namespaces provide a scope for names. Resources in different namespaces can have the same name.
• Resource Quotas: You can set resource quotas for each namespace to limit the amount of resources that can be consumed.
• Access Control: Role-Based Access Control (RBAC) can be applied to namespaces to control access to resources.

To create a namespace, you can use the kubectl command or a YAML configuration file.

Apply the configuration:

To list all namespaces in your cluster, use the following command:

To switch between namespaces, you can use the kubectl config set-context command:

When defining resources, you can specify the namespace in the metadata section of the YAML file:

Let's create a namespace and deploy a pod within that namespace.

Create a file named namespace.yaml:

Apply the configuration:

Create a file named pod.yaml:

Apply the configuration:

1. Create a namespace named test.
2. Deploy a pod named test-pod using the nginx image in the test namespace.
3. Verify that the pod is running in the test namespace.

Solution

1. Create the namespace:

   kubectl create namespace test
   

2. Create a file named test-pod.yaml:

   apiVersion: v1
   kind: Pod
   metadata:
     name: test-pod
     namespace: test
   spec:
     containers:
     - name: nginx
       image: nginx
   

   Apply the configuration:

   kubectl apply -f test-pod.yaml
   

3. Verify the pod:

   kubectl get pods -n test
   

1. Create a namespace named quota-ns.
2. Set a resource quota in the quota-ns namespace to limit the number of pods to 5.

Solution

1. Create the namespace:

   kubectl create namespace quota-ns
   

2. Create a file named resource-quota.yaml:

   apiVersion: v1
   kind: ResourceQuota
   metadata:
     name: pod-quota
     namespace: quota-ns
   spec:
     hard:
       pods: "5"
   

   Apply the configuration:

   kubectl apply -f resource-quota.yaml
   

Namespaces are a powerful feature in Kubernetes that help manage and isolate resources within a cluster. They are essential for organizing resources, applying resource quotas, and implementing access control. By understanding and utilizing namespaces, you can better manage your Kubernetes environment, especially in multi-user and multi-team scenarios.