Libguestfs - May 2013 - Re: How to use libguestfs access LVM as non-root user?

Hi,

Following code snippet, running as non-root user, will throw up a
'Permission denied' RuntimeError.

Could someone kindly guide me the correct way to handle LVM disk as
non-root user? Cause as http://libguestfs.org homepage claims, "libguestfs
doesn't need root permissions."  A little confused somehow.

import guestfs
g = guestfs.GuestFS()
g.add_drive_opts("/dev/vg0/disk1", format="raw")

Thanks!

--
Qiu Yu

On Thu, May 30, 2013 at 10:21:42PM +0800, Qiu Yu wrote:
> Hi,
> 
> Following code snippet, running as non-root user, will throw up a
> 'Permission denied' RuntimeError.
> 
> Could someone kindly guide me the correct way to handle LVM disk as
> non-root user?
> 
> import guestfs
> g = guestfs.GuestFS()
> g.add_drive_opts("/dev/vg0/disk1", format="raw")
Libguestfs doesn't do anything different from any other program.  I'm
assuming that /dev/vg0/disk1 isn't accessible by non-root (by anyone)
on your host.

On most Linux distros you can add yourself to the 'disk' group
in order to get access to disk devices:

  # usermod -G disk -a yourusername

You may need to log out and log in again after doing that.
> Cause as http://libguestfs.org homepage claims, "libguestfs
> doesn't need root permissions."
Right.  This doesn't mean that libguestfs bypasses OS permissions.  It
just means that root isn't required unnecessarily.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
libguestfs lets you edit virtual machines.  Supports shell scripting,
bindings from many languages.  http://libguestfs.org

On Fri, May 31, 2013 at 12:48 AM, Richard W.M. Jones
<rjones@redhat.com>wrote:
> On Thu, May 30, 2013 at 10:21:42PM +0800, Qiu Yu wrote:
> > Hi,
> >
> > Following code snippet, running as non-root user, will throw up a
> > 'Permission denied' RuntimeError.
> >
> > Could someone kindly guide me the correct way to handle LVM disk as
> > non-root user?
> >
> > import guestfs
> > g = guestfs.GuestFS()
> > g.add_drive_opts("/dev/vg0/disk1", format="raw")
>
> Libguestfs doesn't do anything different from any other program. 
I'm
> assuming that /dev/vg0/disk1 isn't accessible by non-root (by anyone)
> on your host.
>
> On most Linux distros you can add yourself to the 'disk' group
> in order to get access to disk devices:
>
>   # usermod -G disk -a yourusername
>
> You may need to log out and log in again after doing that.
>
Unfortunately, the standard 'disk' group permission only applies to
/dev/sdX device nodes, not to device mapper nodes created by LVM commands.

Thank you for the clarification on libguestfs. I'll try to find out other
way to handle LVM device nodes as non-root user.

--
Qiu Yu