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janak0ff
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Update Deployment and Service in Kubernetes

An application deployed on the Kubernetes cluster requires an update with new features developed by the Nautilus application development team. The existing setup includes a deployment named nginx-deployment and a service named nginx-service. Below are the necessary changes to be implemented without deleting the deployment and service:

1.) Modify the service nodeport from 30008 to 32165
2.) Change the replicas count from 1 to 5
3.) Update the image from nginx:1.19 to nginx:latest

Introduction

Imagine you're a DevOps engineer, and the development team just released new features for your application. You need to update the running application without any downtime. How do you do it in Kubernetes?

In this beginner-friendly guide, we'll walk through updating a Kubernetes deployment and service step by step. We'll cover changing service ports, scaling applications, and updating container images—all without deleting anything!

What You'll Learn

  • How to update Kubernetes services and deployments
  • How to scale applications up or down
  • How to update container images
  • How to find and fix common update errors
  • How to verify your updates are working

Table of Contents

  1. Understanding the Scenario
  2. Prerequisites
  3. Step 1: Check Current State
  4. Step 2: Update the Service NodePort
  5. Step 3: Scale the Deployment
  6. Step 4: Update the Container Image
  7. Step 5: Verify All Changes
  8. Common Issues and Solutions
  9. Essential Commands Reference
  10. Best Practices
  11. Conclusion

Understanding the Scenario

The Problem

The Nautilus development team has created new features for their application. They need you to update the existing Kubernetes deployment without deleting anything.

Current Setup

Before the update, we have:

┌─────────────────────────────────────────────────────────┐
│                 Current Setup                          │
├─────────────────────────────────────────────────────────┤
│                                                         │
│  ┌─────────────────────────────────────────────────┐   │
│  │  Deployment: nginx-deployment                   │   │
│  │  Replicas: 1                                   │   │
│  │  Image: nginx:1.19                             │   │
│  └─────────────────────────────────────────────────┘   │
│                                                         │
│  ┌─────────────────────────────────────────────────┐   │
│  │  Service: nginx-service                         │   │
│  │  Type: NodePort                                │   │
│  │  NodePort: 30008                               │   │
│  └─────────────────────────────────────────────────┘   │
│                                                         │
└─────────────────────────────────────────────────────────┘
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What Needs to Change

Component Current New Why?
NodePort 30008 32165 Port conflict or new requirement
Replicas 1 5 High availability and load distribution
Image nginx:1.19 nginx:latest New features and security patches

Desired State 

┌─────────────────────────────────────────────────────────┐
│                 Desired Setup                          │
├─────────────────────────────────────────────────────────┤
│                                                         │
│  ┌─────────────────────────────────────────────────┐   │
│  │  Deployment: nginx-deployment                   │   │
│  │  Replicas: 5                                   │   │
│  │  Image: nginx:latest                           │   │
│  └─────────────────────────────────────────────────┘   │
│                                                         │
│  ┌─────────────────────────────────────────────────┐   │
│  │  Service: nginx-service                         │   │
│  │  Type: NodePort                                │   │
│  │  NodePort: 32165                               │   │
│  └─────────────────────────────────────────────────┘   │
│                                                         │
└─────────────────────────────────────────────────────────┘
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Prerequisites

Before we start, make sure you have:

  • ✅ A Kubernetes cluster (Minikube, kind, or cloud-based)
  • ✅ kubectl configured and working
  • ✅ A deployment named nginx-deployment
  • ✅ A service named nginx-service
  • ✅ Basic understanding of Kubernetes concepts

Step 1: Check Current State

Before making any changes, let's see what we're working with.

Check the Deployment 

kubectl get deployment nginx-deployment
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Expected Output:

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   1/1     1            1           66s
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What This Tells Us:

  • READY: 1/1 - One pod is running and ready
  • UP-TO-DATE: 1 - All pods are on the current version
  • AVAILABLE: 1 - One pod is available to serve traffic

Check the Service 

kubectl get service nginx-service
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Expected Output:

NAME            TYPE       CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
nginx-service   NodePort   10.43.22.56   <none>        80:30008/TCP   66s
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What This Tells Us:

  • TYPE: NodePort - Service is exposed on a node port
  • PORT(S): 80:30008/TCP - Port 80 maps to node port 30008

Check the Pods 

kubectl get pods
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Expected Output:

NAME                                READY   STATUS    RESTARTS   AGE
nginx-deployment-6655dc8cfb-5ps5g   1/1     Running   0          66s
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What This Tells Us:

  • READY: 1/1 - The pod is ready
  • STATUS: Running - The pod is running correctly

Check the Image Version 

kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].image}'
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Expected Output:

nginx:1.19
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Step 2: Update the Service NodePort

The first change we need to make is updating the NodePort from 30008 to 32165.

Option A: Using kubectl edit (Interactive)

This is the most intuitive way for beginners:

kubectl edit service nginx-service
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This opens the service YAML in your default editor. Find the nodePort field and change it:

spec:
  ports:
  - nodePort: 32165    # Change from 30008 to 32165
    port: 80
    protocol: TCP
    targetPort: 80
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Save and exit. The service will update automatically.

💡 Pro Tip: Your editor might be nano, vim, or vi. Use the appropriate commands to save and exit.

Option B: Using kubectl patch (Quick Command)

For a quick update without opening an editor:

kubectl patch service nginx-service -p '{"spec":{"ports":[{"nodePort":32165,"port":80,"protocol":"TCP","targetPort":80}]}}'
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Option C: Using YAML File (Recommended for Production)

First, save the current service YAML:

kubectl get service nginx-service -o yaml > nginx-service.yaml
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Edit the file:

nano nginx-service.yaml
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Change the nodePort:

spec:
  ports:
  - nodePort: 32165
    port: 80
    protocol: TCP
    targetPort: 80
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Apply the changes:

kubectl replace -f nginx-service.yaml
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Verify the Update 

kubectl get service nginx-service
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Expected Output:

NAME            TYPE       CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
nginx-service   NodePort   10.43.22.56   <none>        80:32165/TCP   2m
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Notice the NodePort has changed to 32165!

Step 3: Scale the Deployment

Now let's increase the number of replicas from 1 to 5.

Option A: Using kubectl scale (Recommended) 

kubectl scale deployment nginx-deployment --replicas=5
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Expected Output:

deployment.apps/nginx-deployment scaled
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Option B: Using kubectl edit 

kubectl edit deployment nginx-deployment
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Find and change:

spec:
  replicas: 5    # Change from 1 to 5
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Save and exit.

Option C: Using kubectl patch 

kubectl patch deployment nginx-deployment -p '{"spec":{"replicas":5}}'
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Watch the Scaling Happen

You can watch as new pods are created:

kubectl get pods -w
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Expected Output:

NAME                                 READY   STATUS    RESTARTS   AGE
nginx-deployment-6655dc8cfb-5ps5g    1/1     Running   0          2m
nginx-deployment-6655dc8cfb-7xyzx    0/1     Pending   0          1s
nginx-deployment-6655dc8cfb-8abcd    0/1     Pending   0          1s
nginx-deployment-6655dc8cfb-9efgh    0/1     Pending   0          1s
nginx-deployment-6655dc8cfb-0ijkl    0/1     Pending   0          1s
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After a few seconds, they'll all be running.

Verify the Scaling 

kubectl get deployment nginx-deployment
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Expected Output:

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   5/5     5            5           3m
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Now we have 5 pods running!

kubectl get pods
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Expected Output:

NAME                                 READY   STATUS    RESTARTS   AGE
nginx-deployment-6655dc8cfb-5ps5g    1/1     Running   0          3m
nginx-deployment-6655dc8cfb-7xyzx    1/1     Running   0          30s
nginx-deployment-6655dc8cfb-8abcd    1/1     Running   0          30s
nginx-deployment-6655dc8cfb-9efgh    1/1     Running   0          30s
nginx-deployment-6655dc8cfb-0ijkl    1/1     Running   0          30s
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Step 4: Update the Container Image

Now we need to update the image from nginx:1.19 to nginx:latest.

First: Find the Container Name

This is a common pitfall! You need to know the container name to update it.

kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].name}'
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Or use describe:

kubectl describe deployment nginx-deployment | grep -A 5 "Containers:"
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Expected Output:

Containers:
  nginx-container:
    Image:         nginx:1.19
    Port:          <none>
    Host Port:     <none>
    Environment:   <none>
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The container name is nginx-container.

Update the Image

Option A: Using kubectl set image (Recommended)

kubectl set image deployment/nginx-deployment nginx-container=nginx:latest
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Expected Output:

deployment.apps/nginx-deployment image updated
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Option B: Using Wildcard

kubectl set image deployment/nginx-deployment *=nginx:latest
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Option C: Using Container Index

kubectl set image deployment/nginx-deployment [0]=nginx:latest
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Option D: Using kubectl edit

kubectl edit deployment nginx-deployment
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Find and change:

spec:
  template:
    spec:
      containers:
      - image: nginx:latest    # Change from nginx:1.19
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Watch the Rolling Update 

kubectl rollout status deployment nginx-deployment
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Expected Output:

Waiting for deployment "nginx-deployment" rollout to finish: 1 out of 5 new replicas have been updated...
Waiting for deployment "nginx-deployment" rollout to finish: 2 out of 5 new replicas have been updated...
Waiting for deployment "nginx-deployment" rollout to finish: 3 out of 5 new replicas have been updated...
Waiting for deployment "nginx-deployment" rollout to finish: 4 out of 5 new replicas have been updated...
Waiting for deployment "nginx-deployment" rollout to finish: 5 out of 5 new replicas have been updated...
deployment "nginx-deployment" successfully rolled out
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Understanding the Rolling Update

When you update the image, Kubernetes performs a rolling update:

Before Update:
┌─────────────────────────────────────────────────────────┐
│  Old ReplicaSet (nginx:1.19)                          │
│  ┌───┐ ┌───┐ ┌───┐ ┌───┐ ┌───┐                     │
│  │   │ │   │ │   │ │   │ │   │                       │
│  └───┘ └───┘ └───┘ └───┘ └───┘                     │
│  1    2    3    4    5                               │
└─────────────────────────────────────────────────────────┘

During Update:
┌─────────────────────────────────────────────────────────┐
│  Old ReplicaSet        │  New ReplicaSet               │
│  (nginx:1.19)          │  (nginx:latest)              │
│  ┌───┐ ┌───┐ ┌───┐    │  ┌───┐                      │
│  │   │ │   │ │   │    │  │   │                      │
│  └───┘ └───┘ └───┘    │  └───┘                      │
│  1    2    3           │  4 (new)                    │
│                        │                              │
│  ┌───┐ ┌───┐          │  ┌───┐ ┌───┐               │
│  │   │ │   │          │  │   │ │   │               │
│  └───┘ └───┘          │  └───┘ └───┘               │
│  4    5               │  5 (new)  6 (new)           │
└─────────────────────────────────────────────────────────┘

After Update:
┌─────────────────────────────────────────────────────────┐
│  New ReplicaSet (nginx:latest)                        │
│  ┌───┐ ┌───┐ ┌───┐ ┌───┐ ┌───┐                     │
│  │   │ │   │ │   │ │   │ │   │                       │
│  └───┘ └───┘ └───┘ └───┘ └───┘                     │
│  1    2    3    4    5                               │
└─────────────────────────────────────────────────────────┘
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Key Points:

  • New pods are created before old ones are removed
  • Zero downtime during the update
  • If something goes wrong, Kubernetes stops the update

Step 5: Verify All Changes

Now let's verify everything was updated correctly.

Complete Verification Script 

#!/bin/bash
echo "=== Deployment and Service Update Verification ==="
echo "==================================================="

echo -e "\n📦 DEPLOYMENT STATUS:"
kubectl get deployment nginx-deployment

echo -e "\n🔌 SERVICE STATUS:"
kubectl get service nginx-service

echo -e "\n📊 POD STATUS:"
kubectl get pods -l app=nginx

echo -e "\n🖼️  CURRENT IMAGE:"
kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].image}'
echo ""

echo -e "\n🔢 REPLICA COUNT:"
kubectl get deployment nginx-deployment -o jsonpath='{.spec.replicas}'
echo ""

echo -e "\n🚪 NODEPORT:"
kubectl get service nginx-service -o jsonpath='{.spec.ports[0].nodePort}'
echo ""

echo -e "\n📈 ROLLOUT STATUS:"
kubectl rollout status deployment nginx-deployment

echo -e "\n📋 ROLLOUT HISTORY:"
kubectl rollout history deployment nginx-deployment

echo -e "\n==================================================="
echo -e "✅ All verification complete!"
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Manual Verification Commands

1. Check Deployment:

kubectl get deployment nginx-deployment
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Expected Output:

NAME               READY   UP-TO-DATE   AVAILABLE   AGE
nginx-deployment   5/5     5            5           5m
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2. Check Service:

kubectl get service nginx-service
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Expected Output:

NAME            TYPE       CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
nginx-service   NodePort   10.43.22.56   <none>        80:32165/TCP   5m
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3. Check Pods:

kubectl get pods
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Expected Output:

NAME                                 READY   STATUS    RESTARTS   AGE
nginx-deployment-xxxxxxxxxx-xxxxx    1/1     Running   0          2m
nginx-deployment-xxxxxxxxxx-yyyyy    1/1     Running   0          2m
nginx-deployment-xxxxxxxxxx-zzzzz    1/1     Running   0          2m
nginx-deployment-xxxxxxxxxx-aaaaa    1/1     Running   0          2m
nginx-deployment-xxxxxxxxxx-bbbbb    1/1     Running   0          2m
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4. Check Image:

kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].image}'
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Expected Output:

nginx:latest
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5. Check Replicas:

kubectl get deployment nginx-deployment -o jsonpath='{.spec.replicas}'
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Expected Output:

5
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6. Check NodePort:

kubectl get service nginx-service -o jsonpath='{.spec.ports[0].nodePort}'
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Expected Output:

32165
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7. Check Rollout History:

kubectl rollout history deployment nginx-deployment
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Expected Output:

REVISION  CHANGE-CAUSE
1         <none>
2         <none>
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Common Issues and Solutions

Issue 1: "Unable to find container named 'nginx'"

Error:

error: unable to find container named "nginx"
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Why This Happens:

  • The container name in your deployment isn't nginx
  • Container names are case-sensitive

Solution:

# Find the correct container name
kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].name}'

# Use the correct name
kubectl set image deployment/nginx-deployment <correct-name>=nginx:latest

# Or use wildcard
kubectl set image deployment/nginx-deployment *=nginx:latest
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Issue 2: Service YAML Not Found

Error:

error: the path "nginx-service.yaml" does not exist
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Why This Happens:

  • You tried to use kubectl replace -f but the file doesn't exist

Solution:

# Save the current service to a file
kubectl get service nginx-service -o yaml > nginx-service.yaml

# Edit the file
nano nginx-service.yaml

# Now apply it
kubectl replace -f nginx-service.yaml
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Issue 3: NodePort Already in Use

Error:

Error: node port 32165 is already in use
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Why This Happens:

  • Another service is using the same NodePort

Solution:

# Check what's using the port
kubectl get services --all-namespaces | grep 32165

# Choose a different port
kubectl patch service nginx-service -p '{"spec":{"ports":[{"nodePort":32166,"port":80,"protocol":"TCP","targetPort":80}]}}'
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Issue 4: Rolling Update Stuck

Error:

deployment "nginx-deployment" exceeded its progress deadline
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Why This Happens:

  • New pods aren't becoming ready
  • Image pull issues
  • Resource constraints

Solution:

# Check pod status
kubectl get pods

# Check pod details
kubectl describe pod -l app=nginx

# Check events
kubectl get events --field-selector involvedObject.name=nginx-deployment

# If stuck, rollback
kubectl rollout undo deployment nginx-deployment
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Issue 5: ImagePullBackOff

Error:

ImagePullBackOff
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Why This Happens:

  • Image tag doesn't exist
  • Wrong image name
  • Registry authentication issues

Solution:

# Check if image exists locally
docker pull nginx:latest

# Check the image tag
kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].image}'

# Fix the image tag
kubectl set image deployment/nginx-deployment nginx-container=nginx:1.25
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Essential Commands Reference

Service Commands

Command Description
kubectl get service nginx-service View service details
kubectl describe service nginx-service Detailed service info
kubectl edit service nginx-service Edit service
kubectl patch service nginx-service -p '...' Patch service
kubectl get service nginx-service -o yaml Get service YAML

Deployment Commands

Command Description
kubectl get deployment nginx-deployment View deployment
kubectl scale deployment nginx-deployment --replicas=5 Scale replicas
kubectl set image deployment/nginx-deployment CONTAINER=IMAGE Update image
kubectl rollout status deployment nginx-deployment Check rollout
kubectl rollout history deployment nginx-deployment View history
kubectl rollout undo deployment nginx-deployment Rollback

Pod Commands

Command Description
kubectl get pods List pods
kubectl describe pod POD_NAME Pod details
kubectl logs POD_NAME View logs
kubectl exec -it POD_NAME -- /bin/bash Shell into pod

Verification Commands

Command Description
kubectl get deployment -o jsonpath='{.spec.replicas}' Get replica count
kubectl get deployment -o jsonpath='{.spec.template.spec.containers[0].image}' Get image
kubectl get service -o jsonpath='{.spec.ports[0].nodePort}' Get NodePort
kubectl get pods -l app=nginx Filter by label

Best Practices

✅ DO's

1. Always Check Current State First

# Before making changes
kubectl get deployment,service,pods
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2. Use --dry-run to Test Commands

kubectl set image deployment/nginx-deployment nginx-container=nginx:latest --dry-run=client
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3. Find Container Name Before Updating Images

kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].name}'
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4. Monitor Rollout Status

kubectl rollout status deployment nginx-deployment
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5. Save YAML Files for Repeatability

kubectl get deployment nginx-deployment -o yaml > nginx-deployment.yaml
kubectl get service nginx-service -o yaml > nginx-service.yaml
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6. Use Specific Image Tags in Production

# Development
image: nginx:latest

# Production
image: nginx:1.25.3
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7. Test Changes in Staging First

# Test in staging
kubectl set image deployment/nginx-staging nginx-container=nginx:latest

# After testing, apply to production
kubectl set image deployment/nginx-production nginx-container=nginx:latest
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8. Document Your Changes

kubectl annotate deployment nginx-deployment kubernetes.io/change-cause="Updated to nginx:latest for new features"
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❌ DON'Ts

1. Don't Delete Resources

# BAD - This deletes everything
kubectl delete deployment nginx-deployment
kubectl delete service nginx-service

# GOOD - Update instead
kubectl scale deployment nginx-deployment --replicas=5
kubectl set image deployment/nginx-deployment nginx-container=nginx:latest
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2. Don't Use Wrong Container Names

# BAD - Wrong name
kubectl set image deployment/nginx-deployment nginx=nginx:latest

# GOOD - Check name first
kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].name}'
kubectl set image deployment/nginx-deployment nginx-container=nginx:latest
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3. Don't Forget to Verify

# Always verify after changes
kubectl get deployment,service,pods
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4. Don't Ignore Error Messages

# Read and understand errors
# They tell you exactly what's wrong
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5. Don't Scale Without Understanding Impact

# Consider resource constraints
# Ensure you have enough capacity
kubectl describe nodes
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Complete Real-World Example

Here's a complete session showing the entire process:

# 1. Check current state
echo "=== Current State ==="
kubectl get deployment nginx-deployment
kubectl get service nginx-service
kubectl get pods

# Output:
# NAME               READY   UP-TO-DATE   AVAILABLE   AGE
# nginx-deployment   1/1     1            1           66s
# NAME            TYPE       CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
# nginx-service   NodePort   10.43.22.56   <none>        80:30008/TCP   66s
# NAME                                READY   STATUS    RESTARTS   AGE
# nginx-deployment-6655dc8cfb-5ps5g   1/1     Running   0          66s

# 2. Update service nodePort
echo -e "\n=== Updating Service ==="
kubectl patch service nginx-service -p '{"spec":{"ports":[{"nodePort":32165,"port":80,"protocol":"TCP","targetPort":80}]}}'
# Output: service/nginx-service patched

# 3. Scale deployment
echo -e "\n=== Scaling Deployment ==="
kubectl scale deployment nginx-deployment --replicas=5
# Output: deployment.apps/nginx-deployment scaled

# 4. Find container name
echo -e "\n=== Finding Container Name ==="
kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].name}'
# Output: nginx-container

# 5. Update image
echo -e "\n\n=== Updating Image ==="
kubectl set image deployment/nginx-deployment nginx-container=nginx:latest
# Output: deployment.apps/nginx-deployment image updated

# 6. Monitor rollout
echo -e "\n=== Rollout Status ==="
kubectl rollout status deployment nginx-deployment
# Output: deployment "nginx-deployment" successfully rolled out

# 7. Verify all changes
echo -e "\n=== Final State ==="
kubectl get deployment nginx-deployment
kubectl get service nginx-service
kubectl get pods

echo -e "\n=== Detailed Verification ==="
echo "Replicas: $(kubectl get deployment nginx-deployment -o jsonpath='{.spec.replicas}')"
echo "Image: $(kubectl get deployment nginx-deployment -o jsonpath='{.spec.template.spec.containers[0].image}')"
echo "NodePort: $(kubectl get service nginx-service -o jsonpath='{.spec.ports[0].nodePort}')"
echo "Pods: $(kubectl get pods -l app=nginx --no-headers | wc -l)"

# Output:
# === Final State ===
# NAME               READY   UP-TO-DATE   AVAILABLE   AGE
# nginx-deployment   5/5     5            5           5m
# NAME            TYPE       CLUSTER-IP    EXTERNAL-IP   PORT(S)        AGE
# nginx-service   NodePort   10.43.22.56   <none>        80:32165/TCP   5m
# NAME                                READY   STATUS    RESTARTS   AGE
# nginx-deployment-xxxxxxxxxx-xxxxx   1/1     Running   0          2m
# nginx-deployment-xxxxxxxxxx-yyyyy   1/1     Running   0          2m
# nginx-deployment-xxxxxxxxxx-zzzzz   1/1     Running   0          2m
# nginx-deployment-xxxxxxxxxx-aaaaa   1/1     Running   0          2m
# nginx-deployment-xxxxxxxxxx-bbbbb   1/1     Running   0          2m

# === Detailed Verification ===
# Replicas: 5
# Image: nginx:latest
# NodePort: 32165
# Pods: 5
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Summary

Key Takeaways

  1. Updates Are Easy: Kubernetes makes it simple to update services and deployments
  2. Zero Downtime: Rolling updates ensure your application stays available
  3. Find Container Names First: Always check container names before updating images
  4. Verify Everything: Always check that your updates worked correctly
  5. Use the Right Tools: Different commands for different updates

What You Learned

✅ How to check current deployment and service status
✅ How to update a service NodePort
✅ How to scale a deployment
✅ How to find the correct container name
✅ How to update container images
✅ How to monitor rolling updates
✅ How to verify all changes

Final Status

After completing all updates:

┌─────────────────────────────────────────────────────────┐
│                 Successful Update!                     │
├─────────────────────────────────────────────────────────┤
│                                                         │
│  ✅ Deployment: nginx-deployment                       │
│     Replicas: 5 (scaled from 1)                       │
│     Image: nginx:latest (updated from 1.19)           │
│                                                         │
│  ✅ Service: nginx-service                             │
│     Type: NodePort                                     │
│     NodePort: 32165 (updated from 30008)              │
│                                                         │
│  ✅ Pods: 5 running                                    │
│     Status: All healthy                                │
│                                                         │
└─────────────────────────────────────────────────────────┘
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