Kubernetes Objects - Namespace
Overview
Namespaces provide logical isolation within Kubernetes clusters, enabling organizations to organize resources and manage access control effectively. They serve as virtual clusters within physical clusters, allowing multiple teams or projects to share infrastructure while maintaining separation.
Purpose
Resource Organization
Consider a scenario where 10 different teams share a single file server:
- Files created by one person could be overwritten by another, causing name conflicts
- Separating files that only Team 1 should access becomes challenging, requiring constant permission adjustments
- To resolve this, dedicated folders can be created for each team with permissions configured according to team membership
In the example above, the file server represents the Kubernetes cluster, and namespaces represent the * dedicated folders* created for each team.
Technical Implementation
Namespaces are Kubernetes objects that require proper definition when creating them (especially in YAML files). Namespaces must be independent and unique from each other. Namespaces cannot be nested within each other.
When Kubernetes is initially created, four default namespaces are automatically established: default,
kube-node-lease, kube-public, and kube-system.
Operations
Listing Namespaces
By default, all operations and objects are processed under the default namespace. When executing kubectl get pods
without specifying a namespace, the command retrieves Pods from the default namespace.
kubectl get pods --namespace <namespaceName>
kubectl get pods -n <namespaceName>
# To list Pods across all namespaces:
kubectl get pods --all-namespaces
Creation
kubectl create namespace <namespaceName>
kubectl get namespaces
YAML Configuration
apiVersion: v1
kind: Namespace # A namespace named development is created
metadata:
name: development # Namespace identifier
---
apiVersion: v1
kind: Pod
metadata:
namespace: development # Pod defined under the created namespace
name: namespacepod
spec:
containers:
- name: namespacecontainer
image: nginx:latest
ports:
- containerPort: 80
Important Note: When creating Pods that run in a specific namespace and connecting to these Pods (or performing any operations on them), the namespace must be specified. If not specified, Kubernetes will search for the relevant Pod under the default namespace.
Default Namespace Configuration
kubectl config set-context --current --namespace=<namespaceName>
Deletion
⚠️ CRITICAL WARNING! No confirmation will be requested when deleting a namespace. All objects within the namespace will be permanently deleted!
kubectl delete namespaces <namespaceName>