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Updating container images

General process overview

Argo CD Image Updater can update container images managed by one or more of your Argo CD applications, according to how it is configured.

The workflow of Argo CD Image Updater can be described as follows:

  • It scans for currently configured Argo CD Application resources either using the Kubernetes or the Argo CD API (depending on how you installed the Argo CD Image Updater). The Applications to consider can be further limited by having Argo CD Image Updater selecting only those applications whose name match a given pattern, or match a given label.

  • It then goes through the list of Applications found and inspects each for the the annotation This annotation holds a list of image names that should be updated, and is a mandatory annotation for Argo CD Image Updater to indicate it should process this Application. Read more about the syntax expected in this annotations's value in the marking images for update section in this doc.

  • For each image found in the list, Argo CD Image Updater will first check if this image is actually deployed with the application. It does a strict check for the complete image name, including the registry the image is pulled from. For example, and, while both referring to some/image, are not considered equal. This strict behavior can be relaxed, however. See forcing image updates for further explanation.

  • If Argo CD Image Updater considers an image from the list eligible for an update check, it will connect the corresponding container registry to see if there is a newer version of the image according to the update strategy and other constraints that may have been configured for the image (e.g. a list of tags that are allowed to consider).

  • If a newer version of an image was found, Argo CD Image Updater will try to update the image according to the configured update method. Please note that Argo CD Image Updater will never update your manifests, instead it re-configures your Application sources to use the new image tag, and control is handed over to Argo CD.

Multi-arch images and clusters

As of version 0.12, Argo CD Image Updater has full support for multi-arch images (and multi-arch clusters) by being able to inspect images with multiple manifests (i.e. a manifest list).

Multi-arch currently only is supported for update strategies which fetch image meta-data: latest and digest. Multi-arch will be ignored for the update strategies that do not fetch meta-data, semver and name.

By default, Argo CD Image Updater will only consider updating to images that have a manifest for the same platform where itself runs on. If you are on a cluster that has nodes of multiple architectures, and are pinning certain workloads to certain nodes, you will have to tell Argo CD Image Updater which platforms are allowed for a certain application or an image. This can be done by setting an appropriate annotation per image or for all images of a given application as a default setting.

Multi-arch is also implemented by the test command.

Sync policies and image updates

As explained above, the Argo CD Image Updater will assume that Argo CD will update the manifests in your cluster to use any new image that has been set by the Argo CD Image Updater.

Argo CD Image Updater will work best with automatic syncing enabled for the Argo CD applications that are being updated.

Rollback and image updates

Currently, Argo CD Image Updater does not honor the rollback status of an Argo CD application, and keeps updating to new images also for Applications that are being rolled back. However, Argo CD will disable auto-sync for such applications.

Honoring rollbacked applications correctly is on our roadmap.