I have a dozen server applications installed on my customers intranets (they can send http requests over the internet but cannot be called from outside). They're written in various technologies, mainly java and Go.

I want them to regularly push information about their state towards a central server which is visible on internet. Some of this information is generic (is it ON ?), some is specific (size of a cache in an application for example). The main goal is to be able to make a small web page on which I could instantly check the state of every servers. And maybe later add some kind of notification in case of problem.

Obviously I can do this by writing a few dozen lines of code each side (or a little more if I put this data in a database) but in order to ease future evolution, it could be interesting to use some existing norms or libraries.

So, what are the current opensource free and light solutions to do this, preferably with no central configuration when I add a server ? I'd prefer a norm over a library.