libguestfs/TODO

TODO list for libguestfs
======================================================================

This list contains random ideas and musings on features we could add
to libguestfs in future.

   - RWMJ

FUSE API
--------

The API needs more test coverage, particularly lesser-used system
calls.

The big unresolved issue is UID/GID mapping between guest filesystem
IDs and the host.  It's not easy to automate this because you need
extra details about the guest itself in order to get to its
UID->username map (eg. /etc/passwd from the guest).

febootstrap / debootstrap inside appliance
------------------------------------------

This was originally proposed as a way to install new operating systems
in the appliance.  However no one has come up with a workable
solution.

Haskell bindings
----------------

Complete the Haskell bindings (see discussion on haskell-cafe).

Complete bind tests
-------------------

Complete the bind tests - must test the return values and error cases.

virt-inspector - make libvirt XML
---------------------------------

It should be possible to generate libvirt XML from virt-inspector
data, at least partially.  This would be just another output type so:

 virt-inspector --libvirt guest.img

Note that recent versions of libvirt/virt-install allow guests to be
imported, so this is not so useful any more.

"Standalone/local mode"
-----------------------

Instead of running guestfsd (the daemon) inside qemu, there should be
an option to just run guestfsd directly.

The architecture in this mode would look like:

     +------------------+
     | main program     |
     |------------------|
     | libguestfs       |
     +--------^---------+
          |   | reply
      cmd |   |
     +----v-------------+
     | guestfsd         |
     +------------------+

Notes:

(1) This only makes sense if we are running as root.

(2) There is no console / kernel messages in this configuration, but
we might consider capturing stderr from the daemon.

(3) guestfs_config and guestfs_add_drive become no-ops.

Obviously in this configuration, commands are run directly on the
local machine's disks.  You could just run the commands themselves
directly, but libguestfs provides a convenient API and language
bindings.  Also deals with tricky stuff like parsing the output of the
LVM commands.  Also we get to leverage other code such as
virt-inspector.

This is mainly useful from live CDs, ie. virt-p2v.

Should we bother having the daemon at all and just link the guestfsd
code directly into libguestfs?

Supermin appliance to febootstrap
---------------------------------

Supermin appliance functionality should be moved into febootstrap.

Ideas for extra commands
------------------------

  General glibc / core programs:
    chgrp
    more mk*temp calls

  ext2 properties:
    chattr
    lsattr
    badblocks
    blkid
    debugfs
    dumpe2fs
    e2image
    e2undo
    filefrag
    findfs
    logsave
    mklost+found
    ext2undelete

  SELinux:
    chcat
    restorecon
    ch???

  Oddball:
    pivot_root
    fts(3) / ftw(3)

Other initrd-* commands
-----------------------

Such as:

initrd-extract
initrd-replace

Simple editing of configuration files
-------------------------------------

Some easy non-Augeas methods to edit configuration files.
I'm thinking:

  replace /etc/file key value

which would look in /etc/file for any instances of

  key=...
  key ...
  key:...

and replace them with

  key=value
  key value
  key:value

That would solve about 50% of reconfiguration needs, and for the
rest you'd use Augeas, 'download'+'upload' or 'edit'.

RWMJ: I had a go at implementing this, but it's quite error-prone to
do this sort of editing inside the C-based daemon code.  It's far
better to do it with Augeas, or else to use an external language like
Perl.

Quick Perl scripts
------------------

Currently we can't do Perl "one-liners".  ie. The current syntax for
any short Perl one-liner would be:

  perl -MSys::Guestfs -e '$g = Sys::Guestfs->new(); $g->add_drive ("foo"); $g->launch; $g->mount ("/dev/sda1", "/"); ....'

You can see we're well beyond a single line just getting to the point
of adding drives and mounting.

First suggestion:

 $h = create ($filename, \"/dev/sda1\" => \"/\");

 $h = create ([$file1, $file2], \"/dev/sda1\" => \"/\");

To mount read-only, add C<ro =E<gt> 1> like this:

 $h = create ($filename, \"/dev/sda1\" => \"/\", ro => 1);

which is equivalent to the following sequence of calls:

 $h = Sys::Guestfs->new ();
 $h->set_autosync (1);
 $h->add_drive_ro ($filename);
 $h->launch ();
 $h->mount_ro (\"/dev/sda1\", \"/\");

Command-line form would be:

 perl -MSys::Guestfs=:all -e '$_=create("guest.img", "/dev/sda1" => "/"); $_->cat ("/etc/fstab");'

That's not brief enough for one-liners, so we could have an extra
autogenerated module which creates a Sys::Guestfs handle singleton
(the handle is an implicit global variable as in guestfish), eg:

 perl -MSys::Guestfs::One -e 'inspect("guest.img"); cat ("/etc/fstab");'

How would editing files work?

ntfsclone
---------

Useful imaging tool:
http://man.linux-ntfs.org/ntfsclone.8.html

virt-rescue pty
---------------

See:
http://search.cpan.org/~rgiersig/IO-Tty-1.08/Pty.pm
http://www.perlmonks.org/index.pl?node_id=582185

Note that pty requires cooperation inside the C code too (there are
two sides to a pty, and one has to be handled after the fork).

Windows-based daemon/appliance
------------------------------

See discussion on list:
https://www.redhat.com/archives/libguestfs/2009-November/msg00165.html

qemu locking
------------

Add -drive file=...,lock=exclusive and -drive file=...,lock=shared

Change libguestfs and libvirt to do the right thing, so that multiple
instances of qemu cannot stomp on each other.

virt-disk-explore
-----------------

For multi-level disk images such as live CDs:
http://rwmj.wordpress.com/2009/07/15/unpack-the-russian-doll-of-a-f11-live-cd/

It's possible with libguestfs to recursively look for anything that
might be a filesystem, mount-{,loop} it and look in those, revealing
anything in a disk image.

However this won't work easily for VM disk images in the disk image.
One would have to download those to the host and launch another
libguestfs instance.

List, mount filesystems by UUID and label
-----------------------------------------

[See related:
http://www.redhat.com/archives/libguestfs/2009-August/msg00031.html]

List filesystems by UUID or label.

Mount filesystems by UUID or label.  (I'm not really sure if we can do
this at the moment but we ought to be able to do it, and perhaps make
it easier by having a direct command).

Map filesystems to disk blocks
------------------------------

Map files/filesystems/(any other object) to the actual disk
blocks they occupy.

And vice versa.

Is it even possible?

Integration with host intrusion systems
---------------------------------------

Perfect way to monitor VMs from outside the VM.  Look for file
hashes, log events, login/logout etc.

http://www.ossec.net/
http://la-samhna.de/samhain/
http://sourceforge.net/projects/aide/
http://osiris.shmoo.com/
http://sourceforge.net/projects/tripwire/

Resizing, shrinking, specifying sizes in guestfish
--------------------------------------------------

Owing to an oversight we don't really supporting shrinking
filesystems.  See:

https://bugzilla.redhat.com/show_bug.cgi?id=585221
https://bugzilla.redhat.com/show_bug.cgi?id=585222
https://bugzilla.redhat.com/show_bug.cgi?id=585223

But a related problem is how to specify sizes to guestfish, ie. "100M"
or "1G".  Currently the specific alloc and sparse functions contain
code to parse these size strings, but that cannot be used anywhere
else that would take a byte count.  This is awkward because some
commands take units of megabytes (lvresize, sfdiskM) or sectors
(part-add), with no unifying theme.