[et-mgmt-tools] Greatly improved Xen support for koan

[Michael DeHaan]

For those using Cobbler for virtualization installs, I've commited a 
change to the Mercurial repository that you will probably be interested 
in.  

Basically koan now uses the "virtinst" library to install virtualized 
images rather than using "libvirt" directly.    "virtinst" is the same 
library that virt-manager uses to install virtual machines.   So, how 
does this affect the running of koan?

-- The biggest change is that koan now terminates very quickly, with the 
rest of the virtual installation going on in the background.    This 
allows multiple parallel virtual installs if someone wants to do it.   
This should make koan much more usable in batch context.   If you want 
to watch the installation progress, usage of xm or virt-manager will 
allow that).
-- Koan also names each virtual system after the mac address they are 
created with, such that they are unique.  So no more "xenguest" and 
"xenguest_1" kind of thing, which was error prone when you installed a 
machine and then it crashed, causing naming conflicts.   (--xen-name 
will probably be removed from cobbler also, as it's no longer needed).  
If you are using koan with "--system" instead of "--profile", the MAC 
address can be controlled from cobbler, along with other fine tunning 
arguments.  If not, it will be randomly generated.   If anyone has any 
objections to this naming scheme, you might want to speak up.  I can 
think of a couple of alternate ways to name domains automatically -- 
"$profilename_$timestamp" isn't so bad.
-- Koan no longer writes any files to /var/koan -- anywhere, because it 
doesn't have to.   

This is still undergoing some testing, but I would call it very stable 
at this point.   I'm just going to be tweaking output and error handling 
a bit, if anything.
Further down the road, this will enable koan to do hardware virtual 
installs and handle other virtualization types.  

Note that depending on what distro you are running, Xen will save the 
configuration files in one of the following:
/etc/xen
/var/lib/xen
/var/run/xen

So, if you have domains that get stopped, looking in those directories 
will tell you which ones you have to start.   Also on FC6 and later you 
can experiment with "virsh" for management of inactive domains.

0.2.7 will probably be released sometime later next week ... unless you 
want to play with the upstream code (please do, not too many computers 
have exploded from using it, I promise)

--Michael