Automated Deployments on K3s with ArgoCD Image Updater

ArgoCD Image Updater triggers a deployment by automatically updating the manifest in your Git repo whenever a new image is pushed to the registry. This post covers the annotation-based configuration.

Annotation configuration

Add the following annotations to your Application resource:

metadata:
  annotations:
    argocd-image-updater.argoproj.io/image-list: app=ghcr.io/user/app
    argocd-image-updater.argoproj.io/write-back-method: git
    argocd-image-updater.argoproj.io/app.update-strategy: newest-build

With write-back-method: git, the new image tag gets committed straight back to the repo, preserving ArgoCD’s single-source-of-truth principle.

Write-back with Kustomize

If you’re using Kustomize, the images block in kustomization.yaml gets updated automatically:

kubectl -n argocd logs deploy/argocd-image-updater -f

Once you see Successfully updated image in the logs, the flow is working.

Tip: don’t forget to set up a pull secret for private registries, or Image Updater won’t be able to list tags.

That’s it. From now on, every git push triggers CI to build the image and push it to GHCR, and Image Updater pulls it down to the cluster.