4.9k stars · MIT · v4.33.0 (2026-05-30), read from /releases/latest and confirmed by ungh.cc as 2026-05-30; the yearless '30 May' resolves to 2026 because it is in the past · Track this in Scout
It tells you when a container image you use has a newer version, and it never changes anything.
▶Repo detailsthe review · specs · pros & cons · install
What it is
A single Go program, also published as a container image, that checks registries on a schedule for new tags or changed digests. It can discover what to watch from the containers already running, from a Docker Compose file, from Kubernetes, Swarm or Nomad, or from a plain list.
What it is good for. Any machine running more than three or four containers. The ordinary failure is not dramatic: something you installed eighteen months ago is eighteen months behind, including its security fixes, and nothing ever said so. This is also the safe half of a job that has a dangerous half — the tools that update containers automatically are the ones that break a service at three in the morning. Separating "tell me" from "do it" is the entire design, and it is why this belongs on a machine where an unexpected restart matters.
- MIT, one program, no database, and it holds its state in a small local file.
- It reports through about twenty channels — email, Telegram, Discord, Slack, Gotify, ntfy, a webhook of your own — so it fits whatever you already read.
- It only reads. It has no ability to change a running container, which means it cannot cause an outage.
- It tells you and stops. Applying the update is still a job you do by hand.
- Checking many images often will hit the rate limits on public registries, so the schedule needs a little thought.
- Its newest release, v4.33.0, is dated 30 May 2026, and the code was last pushed on 3 September 2026. It ships slowly, which is normal for a tool this small and worth knowing anyway.
mag37/dockcheckIt answers the same question as a shell script and then offers to apply the updates you pick, where this one runs continuously and never applies anything.
Track this in Scout- containrrr/watchtower
It is the best-known tool for this and it updates containers automatically, but it was archived in December 2025 and its page carries the banner 'This project is no longer maintained'.
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docker run -d --name diun \ -e "TZ=Europe/London" \ -e "DIUN_WATCH_WORKERS=10" \ -e "DIUN_WATCH_SCHEDULE=0 */6 * * *" \ -e "DIUN_PROVIDERS_DOCKER=true" \ -v "$PWD/data:/data" \ -v "/var/run/docker.sock:/var/run/docker.sock" \ crazymax/diun:latest
