[libvirt] [PATCH RFC] Add a virt-host-validate command to sanity check HV config

[Laine Stump]

On 01/10/2012 12:33 PM, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange"<berrange at redhat.com>
>
> To assist people in verifying that their host is operating in an
> optimal manner, provide a 'virt-host-validate' command. For each
> type of hypervisor, it will check any pre-requisites, or other
> good recommendations and report what's working&  what is not.

In general this seems like a very useful idea, and this looks like a 
good start.

I'm wondering how much networking-related stuff we can put in here. For 
example, lately it would have been useful to have a check looking for a 
system-wide dnsmasq instance listening on all interfaces. I also recall 
cases where iptables/ip6tables/radvd weren't installed 
properly/completely (this seems to usually happen on gentoo, due to its 
"build it yourself" nature). But of course that wouldn't signal a 
problem on a system that wasn't intending to have libvirt setup DHCP for 
the guests.

(Oh, another check related to vhost - if the kernel/iptables version is 
"too low" (I would have to look up the exact versions), then vhost-net 
*shouldn't* be loaded if there are RHEL5 (and other older) guests using 
DHCP and getting addresses from a dhcp server on the host. But again, 
that's not *always* a problem.)

(I've been thinking about some sort of program that could diagnose 
problems with the network plumbing of a guest (by looking at brctl/etc 
output, then doing a tcpdump of the vnetX, virbrY, and ethZ interfaces 
while attempting to ping in/out from the guest, and seeing how far the 
traffic went), but aside from the complexity created by needing to 
execute things on the guest, I anyway don't know how much concrete help 
that could give beyond saying "start looking here".)