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Kubernetes Cross-Namespace Communication Command Reference Guide

Project Content Table

Author: Md Toriqul Islam
Description: Comprehensive command reference for implementing cross-namespace communication in Kubernetes
Learning Focus: Kubernetes networking, namespace management, and service discovery
Note: Review each command carefully before execution in your environment.

Section 1: Core Setup Commands

Step 1: Environment Preparation

# Install required tools
sudo apt update
sudo apt install vim -y

# Verify kubectl installation
kubectl version --client

# Create required namespaces
kubectl create namespace namespace-a
kubectl create namespace namespace-b

# Verify namespace creation
kubectl get namespaces

Step 2: Configuration File Creation

# Create Nginx deployment configuration
vim nginx-deployment.yaml

# Create Nginx service configuration
vim nginx-service.yaml

# Create BusyBox pod configuration
vim busybox.yaml

# Verify configuration files
ls -l *.yaml

Section 2: Deployment Operations

Nginx Deployment

# Deploy Nginx in namespace-a
kubectl apply -f nginx-deployment.yaml

# Deploy Nginx service
kubectl apply -f nginx-service.yaml

# Verify Nginx deployment
kubectl get deployments -n namespace-a
kubectl get pods -n namespace-a
kubectl get services -n namespace-a

# Check Nginx pod logs
kubectl logs -n namespace-a -l app=nginx

BusyBox Deployment

# Deploy BusyBox in namespace-b
kubectl apply -f busybox.yaml

# Verify BusyBox deployment
kubectl get pods -n namespace-b

# Check BusyBox pod status
kubectl describe pod busybox -n namespace-b

Section 3: Verification and Testing

Cross-Namespace Communication Testing

# Access BusyBox pod shell
kubectl exec -it busybox -n namespace-b -- sh

# Test DNS resolution
nslookup nginx-service.namespace-a.svc.cluster.local

# Test HTTP connection
wget -qO- http://nginx-service.namespace-a.svc.cluster.local

# Exit BusyBox shell
exit

# Verify service endpoints
kubectl get endpoints -n namespace-a nginx-service

Monitoring and Debugging

# Monitor pod status
kubectl get pods -n namespace-a -w
kubectl get pods -n namespace-b -w

# Check service details
kubectl describe service nginx-service -n namespace-a

# View pod logs
kubectl logs -f -n namespace-a -l app=nginx

Section 4: Cleanup Operations

Resource Cleanup

# Remove deployments and services
kubectl delete -f nginx-deployment.yaml
kubectl delete -f nginx-service.yaml
kubectl delete -f busybox.yaml

# Delete namespaces (caution: removes all resources in namespaces)
kubectl delete namespace namespace-a
kubectl delete namespace namespace-b

# Verify cleanup
kubectl get all -n namespace-a
kubectl get all -n namespace-b

Learning Notes

  1. Kubernetes DNS format: <service-name>.<namespace>.svc.cluster.local
  2. Cross-namespace communication requires proper service exposure
  3. Always verify service endpoints before testing connectivity
  4. Use appropriate namespace contexts for commands
  5. Monitor logs for troubleshooting connection issues

💡 Best Practice: Always verify resource creation in the correct namespace before testing connectivity

⚠️ Warning: Deleting namespaces will remove ALL resources within them

📝 Note: Keep service names consistent across configurations for easier maintenance