[fedora-virt] customizing VMM on a per-user basis to use libguestfs?

Bill Davidsen davidsen at tmr.com
Fri Apr 24 16:00:13 UTC 2009

Daniel P. Berrange wrote:
> On Tue, Apr 21, 2009 at 12:10:31PM -0400, Robert P. J. Day wrote:
>>   is there a mechanism for customizing VMM settings on a per-user
>> basis?  i ask since i'd like to test guestfish and libguestfs on a
>> recently-created VM but, by default, new VM images are created in
>> /var/lib/libvirt/images, and that directory is not accessible to
>> non-root users.
>>   as a non-root user, if i was about to start working with VMs, i'd
>> like to be able to invoke "virt-manager" and, *before* creating any
>> VMs, set some config options, such as where my images are going to go
>> (ideally, in a personal images directory).  that would make those
>> images accessible to my account.
>>   but if i fire up "virt-manager", i can see "Edit" -> "Preferences"
>> but that doesn't allow me that kind of per-user configuration.  does
>> that kind of configuration even exist?  and, with those default
>> settings and permissions, how *would* one use libguestfs and guestfish
>> as a regular user?
>>   or am i once again missing something critical?
> There are two classes of libvirt driver connection
>  - Privileged, per-host connections
>  - Unprivileged, per-user connections
> Xen provides a per-host connection. UserModeLinux and QEMU provide 
> both (qemu:///system and qemu:///session). VirtualBox just proivides
> a per-user instance (vbox:///session) and so on.
> Now by default in Fedora, when connecting to QEMU, virt-manager will
> use the privileged per-host connection, so VMs end up in the system
> directory /var/lib/libvirt/images.
> Our goal (perhaps for F12) should be for local desktop virt use
> cases to use the unprivileged  QEMU connection qemu://session
> by default, and have VM disk images stored in your home directory

I'm not sure that home directory is where people would want images, I 
suspect that an arbitrary location would be far more flexible. Using KVM 
without a VMM, I can put images in someplace obvious, like 
$HOME/virtual/Images (with install ISO images in ~/virtual/ISO) so my 
virtual machines are not co-mingled with other things. My system stuff 
is in /mnt/virtual/Images and people use it by using qemu-img to make a 
local qcow2 images for their personal machines (including test config, 

- did I make clear why some flexibility is desirable?
- is there any technical reason not to make this an arbitrary path?

bill davidsen <davidsen at tmr.com>
  CTO TMR Associates, Inc

"You are disgraced professional losers. And by the way, give us our money back."
    - Representative Earl Pomeroy,  Democrat of North Dakota
on the A.I.G. executives who were paid bonuses  after a federal bailout.

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