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KodeKloud Kubernetes level 1 - Setup Kubernetes Namespaces and PODs

#kubernetes #kodekloud #namespace

The Nautilus DevOps team is planning to deploy some micro services on Kubernetes platform. The team has already set up a Kubernetes cluster and now they want to set up some namespaces, deployments etc. Based on the current requirements, the team has shared some details as below:

Create a namespace named dev and deploy a POD within it. Name the pod dev-nginx-pod and use the nginx image with the latest tag. Ensure to specify the tag as nginx:latest.

Note: The kubectl utility on the jump-host has been configured to work with the Kubernetes cluster.

Setup Kubernetes Namespaces and PODs: Complete Guide

Solution

Step 1: Create the Namespace

First, let's create the dev namespace:

kubectl create namespace dev
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Expected output:

namespace/dev created
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Step 2: Verify the Namespace

Check that the namespace was created:

kubectl get namespaces
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Output:

NAME              STATUS   AGE
default           Active   10d
dev               Active   5s
kube-node-lease   Active   10d
kube-public       Active   10d
kube-system       Active   10d
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Step 3: Create the Pod in the dev Namespace

Now create the pod named dev-nginx-pod using the nginx:latest image in the dev namespace:

kubectl run dev-nginx-pod \
  --image=nginx:latest \
  --namespace=dev \
  --restart=Never \
  --port=80
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Expected output:

pod/dev-nginx-pod created
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Step 4: Verify the Pod

Check if the pod is running in the dev namespace:

kubectl get pods -n dev
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Output:

NAME             READY   STATUS    RESTARTS   AGE
dev-nginx-pod   1/1     Running   0          10s
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Step 5: Get Detailed Information

Check pod details:

kubectl describe pod dev-nginx-pod -n dev
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Step 6: Verify Everything

Let's verify all requirements are met:

# Check pod in dev namespace
kubectl get pods -n dev --show-labels

# Check pod image
kubectl get pod dev-nginx-pod -n dev -o jsonpath='{.spec.containers[0].image}'

# Check pod name
kubectl get pod dev-nginx-pod -n dev -o jsonpath='{.metadata.name}'
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Alternative Methods

Method 1: Using YAML Manifest (Recommended for Production)

Create a file named dev-namespace-pod.yaml:

# Create namespace
apiVersion: v1
kind: Namespace
metadata:
  name: dev
---
# Create pod in dev namespace
apiVersion: v1
kind: Pod
metadata:
  name: dev-nginx-pod
  namespace: dev
  labels:
    app: nginx
    environment: dev
spec:
  containers:
  - name: nginx
    image: nginx:latest
    ports:
    - containerPort: 80
  restartPolicy: Never
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Apply the configuration:

kubectl apply -f dev-namespace-pod.yaml
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Method 2: One-Liner with Namespace

Create namespace and pod in one line:

kubectl create namespace dev && kubectl run dev-nginx-pod --image=nginx:latest --namespace=dev --restart=Never
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Method 3: Using YAML Generation

Generate YAML for the pod in the namespace:

kubectl run dev-nginx-pod \
  --image=nginx:latest \
  --namespace=dev \
  --restart=Never \
  --dry-run=client -o yaml > dev-nginx-pod.yaml

kubectl apply -f dev-nginx-pod.yaml
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Verification Commands

Complete Verification Checklist 

# 1. Check namespace exists
kubectl get namespace dev

# 2. List pods in dev namespace
kubectl get pods -n dev

# 3. Check pod status
kubectl get pod dev-nginx-pod -n dev -o wide

# 4. Check pod image
kubectl get pod dev-nginx-pod -n dev -o jsonpath='{.spec.containers[0].image}'

# 5. Check pod events
kubectl describe pod dev-nginx-pod -n dev | grep -A 5 Events

# 6. Check pod logs (if needed)
kubectl logs dev-nginx-pod -n dev

# 7. Check all resources in dev namespace
kubectl get all -n dev
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Quick Status Check 

# One command to see everything
kubectl get namespace dev && kubectl get pods -n dev
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Pod Operations in the Namespace

Access the Nginx Web Server 

# Port forward to access nginx
kubectl port-forward dev-nginx-pod 8080:80 -n dev

# Then access http://localhost:8080 in browser
# Or use curl in another terminal
curl http://localhost:8080
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Execute Commands in the Pod 

# Get a shell in the pod
kubectl exec -it dev-nginx-pod -n dev -- /bin/bash

# Check nginx version
kubectl exec dev-nginx-pod -n dev -- nginx -v

# List files in nginx web directory
kubectl exec dev-nginx-pod -n dev -- ls -la /usr/share/nginx/html
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View Pod Logs 

# View logs
kubectl logs dev-nginx-pod -n dev

# Follow logs in real-time
kubectl logs -f dev-nginx-pod -n dev

# View previous logs (if pod restarted)
kubectl logs dev-nginx-pod -n dev --previous
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Clean Up

Delete the Pod 

# Delete the pod
kubectl delete pod dev-nginx-pod -n dev
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Delete the Namespace (and all resources in it) 

# Delete the namespace (will delete all resources in it)
kubectl delete namespace dev
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Delete Using YAML 

kubectl delete -f dev-namespace-pod.yaml
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Advanced Namespace Management

1. Create Multiple Namespaces 

kubectl create namespace dev
kubectl create namespace staging
kubectl create namespace production
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2. Set Default Namespace 

# Set default namespace for current context
kubectl config set-context --current --namespace=dev

# Now all commands without -n will use dev namespace
kubectl get pods
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3. Switch Between Namespaces 

# View current context
kubectl config view --minify | grep namespace

# Switch to a different namespace
kubectl config set-context --current --namespace=staging
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4. List All Pods in All Namespaces 

kubectl get pods --all-namespaces
# or
kubectl get pods -A
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5. Resource Quotas in Namespace 

apiVersion: v1
kind: ResourceQuota
metadata:
  name: dev-quota
  namespace: dev
spec:
  hard:
    requests.cpu: "4"
    requests.memory: 8Gi
    limits.cpu: "8"
    limits.memory: 16Gi
    pods: "10"
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6. Limit Ranges in Namespace 

apiVersion: v1
kind: LimitRange
metadata:
  name: dev-limits
  namespace: dev
spec:
  limits:
  - max:
      cpu: "2"
      memory: 4Gi
    min:
      cpu: "100m"
      memory: 128Mi
    default:
      cpu: "500m"
      memory: 256Mi
    defaultRequest:
      cpu: "250m"
      memory: 128Mi
    type: Container
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Namespace Best Practices

✅ DO's

  1. Use namespaces for environment separation

    • dev, staging, production
    • Isolates resources and configurations

  2. Use namespaces for team separation

    • team-engineering, team-data
    • Prevents resource conflicts

  3. Apply resource quotas

    • Prevents one namespace from consuming all resources
    • Ensures fair resource distribution

  4. Use RBAC with namespaces

    • Limit access to specific namespaces
    • Implement least privilege principle

  5. Use labels for categorization

    • environment: dev
    • owner: team-engineering

❌ DON'Ts

  1. Don't use default namespace for production

    • Harder to manage and secure
    • Can cause resource conflicts

  2. Don't create too many namespaces

    • Maintenance overhead
    • Can become confusing

  3. Don't ignore resource limits

    • Can cause cluster instability
    • Impacts other namespaces

  4. Don't use namespaces for very small environments

    • Overhead not worth it
    • Use labels instead

Troubleshooting Namespace Issues

Issue 1: Pod Not Found 

# Error: pod not found
# Solution: Check namespace
kubectl get pods -n dev
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Issue 2: Namespace Not Found 

# Error: namespace "dev" not found
# Solution: Create namespace
kubectl create namespace dev
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Issue 3: Permission Denied 

# Error: unauthorized to access namespace
# Solution: Check RBAC permissions
kubectl auth can-i get pods --namespace=dev
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Issue 4: Resource Quota Exceeded 

# Error: exceeded quota
# Solution: Check quota usage
kubectl describe quota -n dev
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Issue 5: Pod Stuck in Pending 

# Pod stays in Pending state
# Check events
kubectl describe pod dev-nginx-pod -n dev
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Complete Example: Multi-Environment Setup

Here's a complete example with multiple namespaces:

# dev-namespace.yaml
---
apiVersion: v1
kind: Namespace
metadata:
  name: dev
  labels:
    environment: development
    type: non-production
---
apiVersion: v1
kind: Namespace
metadata:
  name: staging
  labels:
    environment: staging
    type: pre-production
---
apiVersion: v1
kind: Namespace
metadata:
  name: production
  labels:
    environment: production
    type: production
---
# Deploy dev pod
apiVersion: v1
kind: Pod
metadata:
  name: dev-nginx-pod
  namespace: dev
  labels:
    app: nginx
    environment: dev
spec:
  containers:
  - name: nginx
    image: nginx:latest
    ports:
    - containerPort: 80
---
# Deploy staging pod (different image version)
apiVersion: v1
kind: Pod
metadata:
  name: staging-nginx-pod
  namespace: staging
  labels:
    app: nginx
    environment: staging
spec:
  containers:
  - name: nginx
    image: nginx:1.21.6
    ports:
    - containerPort: 80
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Apply everything:

kubectl apply -f dev-namespace.yaml
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Quick Reference Commands

Namespace Commands 

# Create namespace
kubectl create namespace <name>

# List namespaces
kubectl get namespaces

# Delete namespace
kubectl delete namespace <name>

# Get namespace details
kubectl describe namespace <name>
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Pod Commands with Namespace 

# Create pod in namespace
kubectl run <pod-name> --image=<image> --namespace=<ns>

# List pods in namespace
kubectl get pods -n <ns>

# Get pod details
kubectl describe pod <pod-name> -n <ns>

# Delete pod from namespace
kubectl delete pod <pod-name> -n <ns>

# Get logs
kubectl logs <pod-name> -n <ns>

# Exec into pod
kubectl exec -it <pod-name> -n <ns> -- /bin/bash
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Lab Completion Summary

✅ Task Requirements Checklist

  • [x] Namespace created: dev namespace exists
  • [x] Pod created: dev-nginx-pod in dev namespace
  • [x] Image specified: Using nginx:latest
  • [x] Pod running: Status is Running with 1/1 READY
  • [x] Proper tagging: Image tag is nginx:latest

Final Verification Command 

# Show everything in one go
echo "=== Namespaces ===" && \
kubectl get namespace dev && \
echo -e "\n=== Pods in dev namespace ===" && \
kubectl get pods -n dev && \
echo -e "\n=== Pod Details ===" && \
kubectl get pod dev-nginx-pod -n dev -o wide && \
echo -e "\n=== Container Image ===" && \
kubectl get pod dev-nginx-pod -n dev -o jsonpath='{.spec.containers[0].image}' && echo
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Expected output:

=== Namespaces ===
NAME   STATUS   AGE
dev    Active   1m

=== Pods in dev namespace ===
NAME             READY   STATUS    RESTARTS   AGE
dev-nginx-pod   1/1     Running   0          45s

=== Pod Details ===
NAME             READY   STATUS    RESTARTS   AGE   IP           NODE
dev-nginx-pod   1/1     Running   0          45s   10.22.0.10   jump-host

=== Container Image ===
nginx:latest
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Success! 🎉

You have successfully:

  1. ✅ Created the dev namespace
  2. ✅ Deployed the dev-nginx-pod pod with nginx:latest image
  3. ✅ Verified the pod is running in the correct namespace
  4. ✅ Demonstrated various operations within the namespace

The Nautilus DevOps team's requirement has been fully satisfied!

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