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In this hands‐on walkthrough, you’ll use Flux’s ImageUpdateAutomation controller to detect new container image tags, commit updates to your Git repository, and deploy the changes automatically on your Kubernetes cluster.

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Overview of Resources

Resource TypePurposeFlux CLI Example
GitRepositoryTracks your application manifests in Gitflux create source git <name> --url=<repo-url> --branch=<branch> --export
ImageUpdateAutomationAutomates image tag updates in YAML and pushes to Gitflux create image update <name> --git-repo-ref=<git-source> --interval=1m --export
Secret (Git deploy key)Holds SSH key for authenticating Git pushesflux create secret git <name> --url=ssh://git@github.com/... --ssh-key-algorithm=ecdsa --export

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Prerequisites

  • A Kubernetes cluster with Flux v0.34+ installed.
  • A Git repository containing your application’s Kubernetes manifests under ./manifests.
  • An ImagePolicy resource in flux-system (e.g., 8-demo-image-policy-bb-app) selecting the desired image tags.
For more details, see the Flux Image Automation Guide and the Flux CLI reference.

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1. Inspect the Flux CLI for Image Updates

Open a terminal in your cluster directory and verify the ImageUpdateAutomation commands: 
flux create image update -h
You should see usage details for creating an ImageUpdateAutomation resource, which watches a Git repo and applies image tag updates to your manifests.

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2. Create the ImageUpdateAutomation Resource

Generate the ImageUpdateAutomation YAML without applying it: 
flux create image update 8-demo-image-update-bb-app \
  --git-repo-ref=8-demo-source-git-bb-app \
  --checkout-branch=8-demo \
  --author-name=fluxcdbot \
  --author-email=fluxcdbot@users.noreply.github.com \
  --git-repo-path="./manifests" \
  --push-branch=8-demo \
  --interval=100s \
  --export > 8-demo-image-update-bb-app.yml
Inspect 8-demo-image-update-bb-app.yml: 
apiVersion: image.toolkit.fluxcd.io/v1beta1
kind: ImageUpdateAutomation
metadata:
  name: 8-demo-image-update-bb-app
  namespace: flux-system
spec:
  interval: 1m40s
  sourceRef:
    kind: GitRepository
    name: 8-demo-source-git-bb-app
  git:
    checkout:
      ref:
        branch: 8-demo
    commit:
      author:
        name: fluxcdbot
        email: fluxcdbot@users.noreply.github.com
    push:
      branch: 8-demo
  update:
    path: ./manifests
    strategy: Setters

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3. Configure the GitRepository Source

Define your application Git source and reconcile it: 
flux create source git 8-demo-source-git-bb-app \
  --url=https://github.com/sidd-harth-2/bb-app-source \
  --branch=8-demo \
  --interval=1m0s \
  --export > 8-demo-source-git-bb-app.yml

kubectl apply -f 8-demo-source-git-bb-app.yml
kubectl apply -f 8-demo-image-update-bb-app.yml

flux reconcile source git 8-demo-source-git-bb-app -n flux-system
flux reconcile image update 8-demo-image-update-bb-app -n flux-system
flux get images all
flux get image update
At this stage, ImageUpdateAutomation will report no updates made, since it doesn’t know where in your manifests to apply new tags.

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4. Mark the Deployment Manifest for Automated Updates

Ensure an ImagePolicy named 8-demo-image-policy-bb-app exists in flux-system to select the desired image tags.
Edit manifests/deployment.yml and annotate the image field: 
apiVersion: apps/v1
kind: Deployment
metadata:
  name: block-buster
  namespace: 8-demo
spec:
  replicas: 1
  template:
    spec:
      containers:
        - name: app
          image: siddharth67/bb-app-flux-demo:7.8.0 # {"$imagepolicy": "flux-system:8-demo-image-policy-bb-app"}
          imagePullPolicy: Always
Commit and push your changes: 
git add manifests/deployment.yml
git commit -m "Add image policy marker"
git push origin 8-demo

flux reconcile source git 8-demo-source-git-bb-app -n flux-system
flux get image update

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5. Handle Git Authentication for Push Access

After marking the manifest, the controller locates the change but cannot push: 
flux get image update
# MESSAGE: authentication required
The image shows a GitHub repository page with a branch selection dropdown open, displaying various branches like "2-demo" and "9-demo." The page includes options for code management, such as "Compare & pull request" and "Add a README."
Go to your GitHub repository Settings → Deploy keys:
The image shows a GitHub repository settings page, specifically the "Deploy keys" section, indicating that there are no deploy keys for the repository.
Generate a deploy key secret and apply it: 
flux create secret git 8-demo-git-bb-app-auth \
  --url=ssh://git@github.com/sidd-harth-2/bb-app-source.git \
  --ssh-key-algorithm=ecdsa \
  --ssh-ecdsa-curve=p521 \
  --export > 8-demo-git-bb-app-auth-secret.yml

kubectl apply -f 8-demo-git-bb-app-auth-secret.yml -n flux-system
Copy the public key from the secret and add it in GitHub as a write deploy key. Authenticate if prompted:
The image shows a GitHub "Confirm access" page prompting the user to enter their password to proceed. It includes a password input field, a "Confirm" button, and links for terms, privacy, and security.

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6. Reconfigure GitRepository Source to Use SSH

Regenerate the GitRepository to reference your SSH URL and secret: 
flux create source git 8-demo-source-git-bb-app \
  --url=ssh://git@github.com/sidd-harth-2/bb-app-source.git \
  --branch=8-demo \
  --secret-ref=8-demo-git-bb-app-auth \
  --timeout=10s \
  --export > 8-demo-source-git-bb-app.yml

kubectl apply -f 8-demo-source-git-bb-app.yml
flux reconcile source git 8-demo-source-git-bb-app -n flux-system

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7. Final Reconciliation and Verification

Trigger the image update and verify the new tag is committed and deployed: 
flux reconcile image update 8-demo-image-update-bb-app -n flux-system
flux get images all
flux get image update
Now Flux will commit the updated tag (e.g., 7.8.1) to your manifests/deployment.yml. Confirm on GitHub:
The image shows a GitHub repository page for "bb-app-source" with a focus on the "manifests" directory, displaying files like "deployment.yml," "namespace.yml," and "service.yml." The branch is 16 commits ahead and 1 commit behind the main branch.
Finally, ensure the new image is running in your cluster: 
kubectl -n 8-demo get deploy block-buster -o wide
Expected output: 
block-buster  1/1  1  1  1m  app  docker.io/siddharth67/bb-app-flux-demo:7.8.1
The image shows a game interface for "Block Buster" with details like pod name, IP, and app version. It prompts the user to "PRESS START" to begin the game.
Congratulations! You’ve successfully automated image tag updates with Flux’s ImageUpdateAutomation controller.

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