diun

Diun is a tool that watches Docker container images and notifies you when updates are available. When you run software using containers, those containers are built from base images that get updated over time, sometimes with new features, sometimes with security fixes. Without something like Diun, you would need to check each image registry manually to see whether a newer version exists, which is easy to forget and easy to fall behind on.

Diun runs in the background and periodically polls the container registries where your images are hosted. When it detects a new tag or a change in an image digest (a fingerprint that changes whenever the image content changes), it sends you a notification. This works with a range of notification services including Discord, Gotify, Slack, and others, so you can route alerts to whatever you already use for operations.

The tool supports several ways of discovering which images to watch. It can monitor Docker containers currently running on a host, watch Kubernetes clusters, read Compose files, or work from a list of images you specify manually. This means it fits into many different infrastructure setups without requiring major changes.

Installation is straightforward: run Diun as a standalone binary or as a Docker container itself. A configuration file lets you set the polling schedule, define which registries to check, and specify how to authenticate with private registries that require credentials.

Diun is written in Go and released under the MIT license. It is self-hosted, meaning you run it on your own machines rather than relying on an external service.