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From Wido den Hollander <>
Subject [KVM] Helper for agent during HA operations
Date Wed, 07 Aug 2013 17:53:05 GMT

In our production setups we have seen some crashes of the KVM agent. 
This could happen for all kinds of reasons, but that's not what I wanted 
to discuss.

Also see this issue:

What I've been writing for a PoC in our company is a small helper 
written in Python which runs on port 8251.

The Investigator can query this webservice (attached) which will simply 
tell it which VMs are running on that host.

It's online here:

You can also do a query like this:

This way we can more reliably verify if a specific VM is still running 
if the Agent stops responding for some reason. A ICMP echo-request isn't 
safe since the Security Groups could prevent ICMP from coming through.

I'd rather not have the management server query libvirt directly, since 
that would open a potential security whole. This webservice is read-only 
and on my production setups I have libvirt listening on the private 
bridge only.

What do you think?


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