A while back I developed VM instance monitoring tool "NIMO", Nova (Openstack's project Nova) Instance Monitor. The need to develop Nimo arise with requirement to monitor VM's boot stages. 

A VM boot undergoes multiple stages, like creating block device, mounting root filesystem, mounting local filesystem, DHCP lease acquiring, post-install activities, etc., and it could fail or stuck at any of these stages. It would be good to have a monitor in place to identify which stage a VM is in while booting and how much time it takes at each stage.

A special need for such tool arise on the cloud space, where end-user do not have access to log on to the hypervisor.

It also helps to people who build custom VM images and add a lot of tasks in post install script and would like to know performance of each step.

The below is the github link and it has an architecture diagram.

I would love to hear all of your response and feel free to use it, extend it.

Thanks,

Jay