Namespaces

Namespaces provide a way to organize and isolate resources within a single Kubernetes cluster. Think on them as virtual clusters inside your physical cluster - they help you separate different applications, environments, or teams while sharing the same underlying infrastructure.

You can think of namespaces like folders on your computer — they let you group related files (resources) without mixing them up.

Namespaces provide:

• Organization: Group related resources together (like all components of an application)
• Isolation: Prevent resource conflicts between different applications or teams
• Resource Management: Apply quotas and limits to specific groups of resources
• Access control: Use Kubernetes permissions (called RBAC — Role-Based Access Control) to decide who can access or change resources.

In this section, you'll explore how namespaces organize resources by working with the different components of our retail store application.

Default Namespaces

Every Kubernetes cluster starts with several built-in namespaces. These are created automatically when a cluster is provisioned:

• default - Where resources go if you don't specify a namespace
• kube-system - System components like DNS and networking
• kube-public - Publicly readable resources
• kube-node-lease - Node heartbeat information

~$kubectl get namespaces

NAME              STATUS   AGE

default           Active   1h

kube-node-lease   Active   1h

kube-public       Active   1h

kube-system       Active   1h

Creating Your First Namespace

Let's create a namespace for our retail store's UI component:

~/environment/eks-workshop/base-application/ui/namespace.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: ui
  labels:
    app.kubernetes.io/created-by: eks-workshop

A

kind: Namespace: Tells Kubernetes what type of resource to create.

B

metadata.name: Unique identifier for this namespace within the cluster.

C

metadata.labels: Key-value pairs that organize and categorize resources.

Apply the configuration file using kubectl

~$kubectl apply -f ~/environment/eks-workshop/base-application/ui/namespace.yaml

You can also create namespaces directly using the kubectl create command. Let's create a namespace for our catalog service and add labels (labels are optional but helpful for organization):

~$kubectl create namespace catalog

~$kubectl label namespace catalog app.kubernetes.io/created-by=eks-workshop

Let's inspect both namespaces:

~$kubectl get namespaces -l app.kubernetes.io/created-by=eks-workshop

The -l flag stands for "label selector" and filters resources based on their labels. In this case, we're only showing namespaces that have the label app.kubernetes.io/created-by=eks-workshop. This is useful for finding resources created by this workshop among all the namespaces in your cluster.

Describe namespace

~$kubectl describe namespace ui

Name:         ui

Labels:       app.kubernetes.io/created-by=eks-workshop

              kubernetes.io/metadata.name=ui

Annotations:  <none>

Status:       Active

No resource quota.

No LimitRange resource.

Using Namespaces

When working with resources, you can specify the namespace in two ways:

Using the -n flag:

~$kubectl get all -n ui

Using the --namespace flag:

~$kubectl get all --namespace ui

Tip: You can also see resources across all namespaces using the -A flag:

~$kubectl get pods -A

Namespaces in this workshop

In this workshop, namespaces help us separate the different microservices that make up our sample retail store application.

• ui - Frontend user interface
• catalog - Product catalog service
• carts - Shopping cart service
• checkout - Order processing service
• orders - Order management service

You'll see commands like this throughout the labs:

~$kubectl get pods -n ui

~$kubectl get secrets -n catalog

This organization makes it easy to:

• See which components belong to which service
• Apply configurations to specific services
• Troubleshoot issues within a particular service

Key Points to Remember

• Namespaces organize and separate resources
• Names must be unique within a namespace
• Most resources are namespaced, some are cluster-wide
• Some resources (like Nodes and PersistentVolumes) are not namespaced and exist at the cluster level.
• Default namespace is used when none specified
• Enable resource quotas and access control