CWATCH (pronounced "quatch" is short for "container watch" - as this project started out as a "how do I do that?" to monitor containers. It has since turned into an image watcher, but "cwatch" sounds better :)
As mentioned above, this started as a "how do I do that?" - and yes, other options are available (i.e. WatchTower) - but that wouldn't have taught me anything. This has been an end to end experiment in getting (re)used to GitHub, DockerHub, Dockerfile and some scripting.
You can find the source on GitHub
You can find the Docker Image on Docker Hub