DEMO Image Automation Controller Update

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.

Overview of Resources

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.

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.

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 \
  [email protected] \
  --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: [email protected]
    push:
      branch: 8-demo
  update:
    path: ./manifests
    strategy: Setters

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.

4. Mark the Deployment Manifest for Automated Updates

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

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

Go to your GitHub repository Settings → Deploy keys:

Generate a deploy key secret and apply it:

flux create secret git 8-demo-git-bb-app-auth \
  --url=ssh://[email protected]/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:

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://[email protected]/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

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:

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

Congratulations! You’ve successfully automated image tag updates with Flux’s ImageUpdateAutomation controller.

Links and References

• Flux Image Automation Guide
• Flux CLI Reference
• Kubernetes Concepts Overview
• GitHub Deploy Keys Documentation