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In this walkthrough, you’ll connect your Kubernetes deployment to Docker Hub and automate updates via Flux GitOps. We’ll cover:
  1. Logging in to Docker Hub
  2. Pulling an existing image
  3. Retagging and pushing to your account
  4. Updating the Kubernetes Deployment manifest
  5. Deploying via Flux
  6. Verifying the live application

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Prerequisites

RequirementPurpose
Docker Hub account (free tier)Host and manage container images
Docker CLI installedBuild, pull, push, and manage images
Clone of the bb-app-source repositorySource manifests for the application
The image shows a Docker login page where a user is prompted to enter their username or email address to continue to Docker Hub.

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1. Log in to Docker Hub

First, clear any existing sessions and then authenticate: 
docker logout
docker login
# Enter your Docker ID and password or access token
# Username: <your-dockerhub-username>
# Password: <your-password-or-access-token>
# Login Succeeded
For security, use a Docker Hub access token instead of your account password.

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2. Pull the Base Image

Fetch the pre-built Block Buster image from the original repository: 
docker pull siddharth67/block-buster-dev:7.8.0
# 7.8.0: Pulling from siddharth67/block-buster-dev
# Digest: sha256:cf54e2a9efad47898d8ae12a3956b2ce7dbc69f239a22804ee78f691
# Status: Image is up to date for docker.io/siddharth67/block-buster-dev:7.8.0

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3. Retag and Push to Your Docker Hub

Tag the image under your own namespace and push: 
docker tag \
  siddharth67/block-buster-dev:7.8.0 \
  <your-username>/bb-app-flex-demo:7.8.0

docker push <your-username>/bb-app-flex-demo:7.8.0
# Pushing layers to <your-username>/bb-app-flex-demo
# latest: digest: sha256:cfc54e2a396562b2ce7dbc69f239a22804e78f691 size: 3662
Replace <your-username> consistently. Never commit credentials or tokens into Git repositories.
After a successful push, confirm that the bb-app-flex-demo repository with tag 7.8.0 appears in your Docker Hub account.

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4. Update the Kubernetes Deployment Manifest

Switch to the 8-demo branch and edit the deployment to reference your image: 
cd ../bb-app-source/
git checkout 8-demo
Open deployment.yaml and update the container image: 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: blockbuster
  namespace: dev
spec:
  replicas: 1
  selector:
    matchLabels:
      app: blockbuster
  template:
    metadata:
      labels:
        app: blockbuster
    spec:
      containers:
        - name: app
          image: <your-username>/bb-app-flex-demo:7.8.0
          imagePullPolicy: Always
          resources:
            requests:
              memory: "10Mi"
              cpu:    "100m"
Commit and push your change: 
git add deployment.yaml
git commit -m "chore: update image to <your-username>/bb-app-flex-demo:7.8.0"
git push origin 8-demo

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5. Deploy with Flux

In your Flux cluster repository, create a GitRepository source and Kustomization: 
cd ../block-buster/flux-clusters/dev-cluster

# Define the Git source tracking the 8-demo branch
flux create source git bb-app-source \
  --url https://github.com/sidd-harth-2/bb-app-source \
  --branch 8-demo \
  --interval 1m \
  --export > bb-app-source.yaml

# Create a Kustomization to apply manifests from the source
flux create kustomization bb-app-kustomize \
  --source GitRepository/bb-app-source \
  --path ./manifests \
  --prune true \
  --interval 1m \
  --target-namespace dev \
  --export > bb-app-kustomize.yaml

# Apply the Flux resources
kubectl apply -f bb-app-source.yaml
kubectl apply -f bb-app-kustomize.yaml
Trigger an immediate reconciliation and verify: 
flux reconcile source git flux-system
flux reconcile kustomization flux-system

kubectl get ns
# NAME           STATUS   AGE
# dev            Active   1m
kubectl -n dev get all
# Confirm the blockbuster Deployment, Service, Pod, etc.

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6. Verify the Application

Point your browser to the NodePort (e.g., localhost:30008) and confirm the high score persistence in version 7.8.0:
The image shows a screenshot of a block-breaking game called "Block Buster" with a "Game Over" message. The game interface includes colorful blocks, a paddle, and a ball, along with game information like score and lives.
You’ve now integrated Docker Hub with Kubernetes and automated your deployment using Flux GitOps. Next up: creating a FluxRepository to track image updates and automate version bumps.

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