Libguestfs - Mar 2012 - mounting using guestfish

[Please remember to post all questions on the mailing list]

On Thu, Mar 08, 2012 at 09:41:19PM +0700, Tho Huynh
wrote:
> Can I mount the guest's file system into a folder/path (mountpoint)
> in the host machine using guestfish?
No, but you don't need to.
> And accessing that folder equal to accessing the guest's file
> system.  What I'm trying to do is to copy a file from one guest to
> another directly but to achieve full disk speed.
Guestfish cannot connect to two guests at the same time, so you would
need to download the file from one guest and upload it to the other.
(I'm still assuming here that you are using libguestfs live).  eg:

  guestfish --live -d Source download /some/file /tmp/file
  guestfish --live -d Destination upload /tmp/file /some/file

If that isn't fast enough or you need to avoid the local copy, it is
possible to connect two handles together and copy the file directly
between them, but you'd have to write a script against the API (eg. in
Perl/Python/etc).

	.  .  .

In the *non-live* case, there is another method: add the disks of both
guests, 'launch', and copy the file between mountpoints (see the
'mkmountpoint' command).  Surprisingly, this is not necessarily going
to be faster than downloading and uploading.  This method also has
some limitations -- it's not possible to use two guests that have
conflicting volume group names; and even security issues -- a
malicious guest could interfere with the other guest.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.  Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/

hi Mr Rich.
I`m new to programming on Linux, new to Perl, Python.
How long do you think it will take me to finish the script ?
Thank you.
Comment if you have time :)


________________________________
 From: Richard W.M. Jones <rjones at redhat.com>
To: Tho Huynh <feeliwood at yahoo.com>; libguestfs at redhat.com 
Sent: Friday, 9 March 2012, 1:23
Subject: Re: mounting using guestfish
 
[Please remember to post all questions on the mailing list]

On Thu, Mar 08, 2012 at 09:41:19PM +0700, Tho Huynh
wrote:
> Can I mount the guest's file system into a folder/path (mountpoint)
> in the host machine using guestfish?
No, but you don't need to.
> And accessing that folder equal to accessing the guest's file
> system.? What I'm trying to do is to copy a file from one guest to
> another directly but to achieve full disk speed.
Guestfish cannot connect to two guests at the same time, so you would
need to download the file from one guest and upload it to the other.
(I'm still assuming here that you are using libguestfs live).? eg:

? guestfish --live -d Source download /some/file /tmp/file
? guestfish --live -d Destination upload /tmp/file /some/file

If that isn't fast enough or you need to avoid the local copy, it is
possible to connect two handles together and copy the file directly
between them, but you'd have to write a script against the API (eg. in
Perl/Python/etc).

??? .? .? .

In the *non-live* case, there is another method: add the disks of both
guests, 'launch', and copy the file between mountpoints (see the
'mkmountpoint' command).? Surprisingly, this is not necessarily going
to be faster than downloading and uploading.? This method also has
some limitations -- it's not possible to use two guests that have
conflicting volume group names; and even security issues -- a
malicious guest could interfere with the other guest.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-df lists disk usage of guests without needing to install any
software inside the virtual machine.? Supports Linux and Windows.
http://et.redhat.com/~rjones/virt-df/
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On Fri, Mar 09, 2012 at 01:11:23AM -0800, THO HUYNH
wrote:
> Do you have any documentation about the implementation of mounting
> using guestfish.  I want to know how it works inside then write the
> script.
Libguestfs live access works slightly differently from ordinary use of
libguestfs, and all the examples only explain the ordinary way.

The main documentation is here:

http://libguestfs.org/guestfs.3.html#api_overview

Once you've decided what language you want to use, you'll need to
follow one of these pages:

http://libguestfs.org/guestfs-perl.3.html
http://libguestfs.org/guestfs-python.3.html
http://libguestfs.org/guestfs-ocaml.3.html
http://libguestfs.org/guestfs-ruby.3.html
http://libguestfs.org/guestfs-java.3.html

Because it's live, you need to add the domain using the 'live'
option,
see:

http://libguestfs.org/guestfs.3.html#guestfs_add_domain

To download and upload between handles, you'll need to use two
threads, a pipe between them, and the regular download/upload APIs:

http://libguestfs.org/guestfs.3.html#guestfs_download
http://libguestfs.org/guestfs.3.html#guestfs_upload
http://libguestfs.org/guestfs.3.html#guestfs_tar_out
http://libguestfs.org/guestfs.3.html#guestfs_tar_in
(etc)

I suggest writing some code and reading the many programs in the
source of libguestfs, and if you get stuck, posting specific questions
on the mailing list.

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
New in Fedora 11: Fedora Windows cross-compiler. Compile Windows
programs, test, and build Windows installers. Over 70 libraries supprt'd
http://fedoraproject.org/wiki/MinGW http://www.annexia.org/fedora_mingw