[Libguestfs] Can't access remote URI

[Richard W.M. Jones]

On Thu, Dec 20, 2012 at 06:30:12PM +0800, Wanlong Gao wrote:
> On 12/20/2012 05:53 PM, Richard W.M. Jones wrote:
> > On Thu, Dec 20, 2012 at 05:30:03PM +0800, Wanlong Gao wrote:
> >> On 12/20/2012 05:08 PM, Richard W.M. Jones wrote:
> >>> 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.
> >>
> >> So, at this time, we should report a useful message to user but not just
> >> fail without any thing. Right?
> > 
> > I don't know how you can report a useful message, since it's not
> > obvious if a libvirt URI is remote.  eg. How about the URI
> > "qemu+ssh://foo/session" where the hostname of the local machine is
> > "foo.example.com"?  Or the hostname is "bar.example.com" but the local
> > DNS contains a PTR record "foo" -> "bar"?
> 
> Oops, I don't have a good idea either.
> So, as John is doing this work, can you share the working progress and the roadmap
> so that we can help doing something?

[Adding John to the CC list]

Rich.

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