Libguestfs - Dec 2012 - Can't access remote URI

Hi Rich,

We just found that the libguestfs can't access the remote URI.
When doing guestfs__add_drive_opts(), we always add files from
local system, it's related the -c|--connect option.

As I know, we are using local kernel to lunch the min-guest,
and it's hard to attach remote disks to our local min-guest.

Our test team found this problem by using following command,

# virt-sysprep -c qemy+ssh://<host>/system -d domname

Then, for example the path of remote disk is /work/rhel.img,
but we are about to access the /work/rhel.img locally.

So, IMHO, if we are about to not support the remote URI, we
should give a error message first. But access local disks
instead of remote disks are definitely wrong here.

Maybe we also need document this.

Any thoughts?

Thanks,
Wanlong Gao

On Thu, Dec 20, 2012 at 04:00:10PM +0800, Wanlong Gao
wrote:
> Hi Rich,
> 
> We just found that the libguestfs can't access the remote URI.
> When doing guestfs__add_drive_opts(), we always add files from
> local system, it's related the -c|--connect option.
> 
> As I know, we are using local kernel to lunch the min-guest,
> and it's hard to attach remote disks to our local min-guest.
> 
> Our test team found this problem by using following command,
> 
> # virt-sysprep -c qemu+ssh://<host>/system -d domname
> 
> Then, for example the path of remote disk is /work/rhel.img,
> but we are about to access the /work/rhel.img locally.
> 
> So, IMHO, if we are about to not support the remote URI, we
> should give a error message first. But access local disks
> instead of remote disks are definitely wrong here.
> 
> Maybe we also need document this.
> 
> Any thoughts?
John Eckersberg is working on implementing this for libguestfs 1.22.
Most of the libvirt support has been done already, but there is some
more libvirt and libguestfs work.

As for reporting an error, it's difficult because libvirt doesn't give
a simple way to find out if a URI is "remote" or not (whatever
"remote" means).  And even if libvirt did, it's not necessarily
true
that remote URIs wouldn't work, eg. if the user attached a LUN to both
the remote and local machine.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
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