What are Kubernetes namespaces?

Kubernetes namespaces logically divide and isolate resources within a Kubernetes cluster. They provide a virtual cluster-like environment within a physical cluster, allowing multiple teams or applications to share the same underlying infrastructure while maintaining separation and avoiding naming conflicts.

Namespace necessity

A namespace enhances resources’ reusability, isolation, and maintenance smoothly. If we don’t use a namespace, all of our allocated resources will be under one roof which can cause multiple problems when working with cross-team. Some of the challenges are as follows:

• Lack of resource isolation
• Naming conflicts
• Limited access control
• Reduced organization and visibility
• Resource allocation challenges
• Maintenance and scalability

Default namespaces

Kubernetes has four default namespaces: default, kube-system, kube-public, and kube-node-lease. When we create resources without explicitly specifying a namespace, they are automatically assigned to the default namespace. At the same time, kube-system contains all system-level resources. The kube-public namespace encompasses resources that need to be publically available, and kube-node-lease contains lease resources that enable nodes to maintain their availability. The default namespaces are created automatically when setting up a Kubernetes cluster.

The illustrations above describe how our resources reside in a default namespace without proper isolation. In this scenario, all resources from different teams or applications are created within the default namespace. If both teams create deployments of the same name but different configurations, it could override the wrong application, messing up the whole system.

Custom namespaces

User-defined namespaces are necessary to manage resources, enforce access controls, and maintain better organization within the cluster. These namespaces are specifically created to meet the needs and requirements of different teams, projects, or applications.

It allows isolation for each resource and makes the management more effective. Moreover, it enhances the reusability of components and restricts access by changing the permissions, as shown in the following illustration.

In conclusion, Kubernetes namespaces are essential for effective resource management and promoting collaboration in Kubernetes environments.