Ask HN: An internal catalog of web app stack versions?

I'm looking for a solution for maintaining an internal catalog of websites and web applications, which are being hosted on multiple different servers and software stacks. This catalog should be able to notify the admins when new versions or security updates of stack components are available. I would like to see in one glance how stale the app dependencies are becoming over time.

Typically, the stacks in my case are Node.js, Python, Ruby or PHP based, so it should be possible for a catalog system to scan the official repositories (NPM, PyPi, Gems, etc) for new versions of packages and compare that to the apps' currently installed versions.

Any ideas how this could be done, besides just coding a system (or a bunch of scripts) from scratch to do it?