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How to Create a Namespace in Kubernetes

Namespaces provide a mechanism for isolating groups of resources within a single cluster. This guide will show you how to create and manage namespaces effectively.

Prerequisites

  • Running Kubernetes cluster
  • kubectl installed and configured
  • Basic understanding of Kubernetes resources

Creating Namespaces

Create a file named development-namespace.yaml:

apiVersion: v1
kind: Namespace
metadata:
  name: development
  labels:
    name: development
    environment: dev

Apply the namespace: 

kubectl apply -f development-namespace.yaml

Method 2: Using Command Line

# Create namespace directly
kubectl create namespace development

Working with Namespaces

List Namespaces

# List all namespaces
kubectl get namespaces

# Get detailed namespace information
kubectl describe namespace development

Set Default Namespace

# Change default namespace for current context
kubectl config set-context --current --namespace=development

# Verify current namespace
kubectl config view --minify | grep namespace:

Resource Management in Namespaces

1. Create Resources in Namespace

Deploy an application in a specific namespace:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: development
spec:
  replicas: 3
  selector:
    matchLabels:
      app: nginx
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2

2. Resource Quotas

Create resource-quota.yaml:

apiVersion: v1
kind: ResourceQuota
metadata:
  name: dev-quota
  namespace: development
spec:
  hard:
    requests.cpu: "4"
    requests.memory: 4Gi
    limits.cpu: "8"
    limits.memory: 8Gi
    pods: "10"
    configmaps: "10"
    persistentvolumeclaims: "4"
    services: "10"
    secrets: "10"
    services.loadbalancers: "2"

3. Limit Range

Create limit-range.yaml:

apiVersion: v1
kind: LimitRange
metadata:
  name: dev-limits
  namespace: development
spec:
  limits:
  - default:
      cpu: 500m
      memory: 512Mi
    defaultRequest:
      cpu: 200m
      memory: 256Mi
    type: Container

Namespace Isolation

Network Policies

Create namespace-network-policy.yaml:

apiVersion: networking.k8s.io/v1
kind: NetworkPolicy
metadata:
  name: namespace-isolation
  namespace: development
spec:
  podSelector: {}
  policyTypes:
  - Ingress
  ingress:
  - from:
    - namespaceSelector:
        matchLabels:
          environment: dev

Production Namespace Setup Example

# production-namespace-setup.yaml
---
apiVersion: v1
kind: Namespace
metadata:
  name: production
  labels:
    name: production
    environment: prod
    compliance: pci
---
apiVersion: v1
kind: ResourceQuota
metadata:
  name: prod-quota
  namespace: production
spec:
  hard:
    requests.cpu: "16"
    requests.memory: "32Gi"
    limits.cpu: "32"
    limits.memory: "64Gi"
    pods: "50"
---
apiVersion: v1
kind: LimitRange
metadata:
  name: prod-limits
  namespace: production
spec:
  limits:
  - default:
      cpu: "1"
      memory: "1Gi"
    defaultRequest:
      cpu: "500m"
      memory: "512Mi"
    max:
      cpu: "4"
      memory: "8Gi"
    type: Container

Best Practices

1. Naming Conventions

  • Use meaningful, descriptive names
  • Follow a consistent naming scheme
  • Add relevant labels

Example: 

metadata:
  name: customer-portal-prod
  labels:
    environment: production
    team: customer-portal
    cost-center: cc123

2. Resource Organization

  • Group related resources in the same namespace
  • Use separate namespaces for different environments
  • Implement proper resource quotas

3. Security

  • Implement RBAC per namespace
  • Use network policies for isolation
  • Set appropriate resource limits

4. Monitoring

  • Set up monitoring per namespace
  • Configure alerts based on namespace
  • Track resource usage by namespace

Common Operations

Viewing Resources in Namespace

# List all resources in namespace
kubectl get all -n development

# Get specific resource type
kubectl get pods -n development

Deleting Resources

# Delete specific resource
kubectl delete pod pod-name -n development

# Delete all resources in namespace
kubectl delete all --all -n development

# Delete namespace and all its resources
kubectl delete namespace development

Troubleshooting

Common Issues and Solutions

  1. Namespace Stuck in Terminating State 

    # Force delete namespace
kubectl get namespace development -o json > tmp.json
# Edit tmp.json and remove "kubernetes" from finalizers
curl -k -H "Content-Type: application/json" -X PUT --data-binary @tmp.json \
http://localhost:8001/api/v1/namespaces/development/finalize

  2. Resource Quota Exceeded 

    # Check quota usage
kubectl describe resourcequota -n development

# Check pod resource requests/limits
kubectl describe pod pod-name -n development

  3. Permission Issues 

    # Check RBAC permissions
kubectl auth can-i create pods -n development

Next Steps

  1. Learn about RBAC for namespace access control
  2. Implement monitoring for namespace resources
  3. Set up CI/CD pipelines with namespace isolation
  4. Configure network policies between namespaces
  5. Implement multi-tenancy using namespaces