I am looking for library to support server / switch monitoring, to actually be able to check with the device if it's working OK. However this requires some sort of auto-detection and device support.

Basically I need to automatically detect a new device, start monitoring it like CPU and PING. So how do I auto-detect the machine remotely, this is something I need library for.

Rackspace has something like this - "Cloud Monitoring API". But is there anything opensource which can be used same way?

The Nagios and others doesnt have such API, and the big and expensive systems are too big to handle in public cloud, so there must be some other network monitoring engine with API, which can add a new servers automatically and support user isolation for example so I dont see other servers except mine.