Add Uptime kuma community container - #8495

I answered there.

@derStephan Thank you for your first PR! 👏

I think it's a nice idea to integrate a full, standalone monitoring tool like this, and would prefer it over tools like "upptime" that rely on github.com.

My main problem with this is the integration of the docker socket, because it is such a gaping security boundary violation waiting to be exploited. I know some other community containers are using it, too, and I'm unhappy with that, and at least would like to not allow even more containers to use it.

From my perspective this would also be useful without the docker socket. It would require more configuration work, and provide less details automatically, but that's the price for better security protection, I'd say.

@derStephan Do you think you could change the integration to work like that? For Nextcloud there's e.g. /status.php as easy monitoring target.

Apart from this fundamental issue I'd have a few smaller remarks, which I'll hold back until we found a common ground.

@pabzm Thank you for your thoughts.

I generally agree that this can be a security issue. However, it only allows read-only access to the socket. And without that, it is still useful for remote servers but not for the internal health documentation. Glances container is using this socket as well because without it, it will be useless.

The status.php requires a running nextcloud and will not alert in cases like #8437.

I can put a fat warning in the readme - as I did for the downtime during backups. Then the actual user can decide.

done.