Zenoss – Cloud Monitoring Tool
Zenoss is an open-source platform released under the GNU General Public License (GPL) version 2. It provides easy to use web UI to monitor performance, events, configuration, and inventory. Zenoss is one of the best for unified monitoring since it is Cloud agnostic and is also available as open-source. Zenoss provides powerful plugins named Zenpacks. It supports monitoring on Hypervisors (ESX, KVM, Xen, HyperV), Private Cloud Platforms (CloudStack, OpenStack, vCloud/vSphere), and Public Clouds (AWS).