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Cover image for Part-88: 🔄 Kubernetes Deployment Updates & Rollout Verification in GCP (Google Kubernetes Engine)
Latchu@DevOps
Latchu@DevOps

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Part-88: 🔄 Kubernetes Deployment Updates & Rollout Verification in GCP (Google Kubernetes Engine)

#kubernetes #cloud #devops #learning

In this guide, we’ll learn how to update Kubernetes Deployments in Google Kubernetes Engine (GKE) using two methods:

  1. kubectl set image (direct image update)
  2. kubectl edit deployment (manual YAML edit)

We’ll also verify rollout status, ReplicaSets, Pods, and rollout history step by step.

📌 Step 00: Introduction

Kubernetes supports updating Deployments in two ways:

  • Set Image → Quick way to update the container image directly.
  • Edit Deployment → Manual way to edit deployment YAML and change the image (or other fields).

By default, updates are performed using a rolling update strategy, ensuring zero downtime.

🔹 Step 01: Update Application (V1 → V2) using set image

1️⃣ Get Container Name from Deployment

kubectl get deployment my-first-deployment -o yaml
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2️⃣ Update Deployment to V2

kubectl set image deployment/my-first-deployment \
  kubenginx=ghcr.io/stacksimplify/kubenginx:2.0.0
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🔍 Verify Rollout

# Check rollout status
kubectl rollout status deployment/my-first-deployment

# Verify deployment details
kubectl get deploy
kubectl describe deployment my-first-deployment
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d1

✅ Kubernetes performs a rolling update, gradually replacing old Pods with new ones without downtime.

🔍 Verify ReplicaSets & Pods

# Check ReplicaSets
kubectl get rs

# Check Pods
kubectl get po
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d2

📌 Observation: A new ReplicaSet is created for version 2.0.0, while old ReplicaSet is scaled down.

🌍 Access Application

# Get LoadBalancer IP
kubectl get svc

# Access via browser or curl
http://<External-IP>
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d3

✅ You should now see Application Version: V2.

📝 Update Change-Cause for Rollout History

# View rollout history
kubectl rollout history deployment/my-first-deployment

# Annotate with change cause
kubectl annotate deployment/my-first-deployment \
  kubernetes.io/change-cause="Deployment UPDATE - App Version 2.0.0 - SET IMAGE OPTION"

# Verify rollout history
kubectl rollout history deployment/my-first-deployment
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d4

🔹 Step 02: Update Application (V2 → V3) using edit deployment

1️⃣ Edit Deployment YAML

kubectl edit deployment/my-first-deployment
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Change the image version:

# From
image: ghcr.io/stacksimplify/kubenginx:2.0.0

# To
image: ghcr.io/stacksimplify/kubenginx:3.0.0
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d5

🔍 Verify Rollout

# Rollout status
kubectl rollout status deployment/my-first-deployment

# Deployment details
kubectl describe deployment/my-first-deployment
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d6

🔍 Verify ReplicaSets & Pods

kubectl get rs
kubectl get po
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📌 Observation: Now we should see 3 ReplicaSets (V1, V2, V3).

d6

🌍 Access Application

kubectl get svc
http://<External-IP>
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✅ Application should now display Version: V3.

d7

📝 Update Change-Cause for Rollout History 

# Rollout history
kubectl rollout history deployment/my-first-deployment

# Annotate with change cause
kubectl annotate deployment/my-first-deployment \
  kubernetes.io/change-cause="Deployment UPDATE - App Version 3.0.0 - EDIT DEPLOYMENT OPTION"

# Verify rollout history again
kubectl rollout history deployment/my-first-deployment
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d8

✅ Recap

In this tutorial, we:

  • Updated a Deployment using kubectl set image
  • Updated another version using kubectl edit deployment
  • Verified rollout status, ReplicaSets, and Pods
  • Annotated rollouts for better history tracking

🎉 With Kubernetes in GCP, updates are seamless, zero-downtime, and fully auditable.

🌟 Thanks for reading! If this post added value, a like ❤️, follow, or share would encourage me to keep creating more content.

— Latchu | Senior DevOps & Cloud Engineer

☁️ AWS | GCP | ☸️ Kubernetes | 🔐 Security | ⚡ Automation
📌 Sharing hands-on guides, best practices & real-world cloud solutions

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