I’m a Nagios admin, use it to monitor various items.
In the old days Nagios was used with things like NRPE and NCSA etc, still popular but the best IMHO now is passive checks via NCPA.
NCPA has two services, one is ncpa_listener and the other is ncpa_passive. As the names suggest, one is a listener which listens on each node port 5693, while the other is the passive check system which reads configs for the checks to send to the NRDP server running on the Nagios server.
NCPA though, via it’s listening port 5693 and via URL’s / API can be called, to pull all sorts of stuff from cpu, mem, disks, etc to calling any nagios plugin etc.
My suggestion would be to be able to call NCPA to it’s URL’s to pull any details wanted into LibreNMS.
One could then simply use current NCPA infrastructure (which is on all endpoints) to graph items that Nagios (core) doesn’t do.
For one environment I work on this would be extremely useful and will get LibreNMS into that environment to not only handle NCPA-based nodes, but every other network device that needs graphing.