TODO list for libguestfs
======================================================================
This list contains random ideas and musings on features we could add
to libguestfs in future.
- RWMJ
Python bindings
---------------
Ideas for the Python bindings:
https://www.redhat.com/archives/fedora-virt/2009-April/msg00114.html
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).
BufferIn
--------
BufferIn should turn into <char *, int> and simple strings in other
languages that can handle 8 bit clean strings.
Limit on transfers would still be 2MB for these types.
- then implement write-file properly
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?
PPC problems
------------
[This section should be filed as bugs, but no one seems to care for
PPC hosts and the hardware is rapidly becoming obsolete]
ppc (32 bit) works with qemu from git, however there is no serial console
ppc64 requires extra parameters:
-M mac99 -cpu ppc64
however it still fails:
invalid/unsupported opcode: 01 - 01 - 1a (06301e83) 00000000018c2738 1
invalid bits: 00400000 for opcode: 0b - 19 - 15 (2d746572) 0000000000009230
no serial console in ppc or ppc64 because no one can tell us what
console=ttyXX option to use
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
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
Standard images
---------------
Equip guestfish with some standard images that it can load
quickly, eg:
load ext2
Maybe it's better to create these on the fly?
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).
virt-rescue TERM
----------------
Pass TERM from the library, through the kernel command line, to the
init script.
Windows-based daemon/appliance
------------------------------
See discussion on list:
https://www.redhat.com/archives/libguestfs/2009-November/msg00165.html
virt-grow, virt-shrink
----------------------
Grow and shrink existing guests. The main problem comes with
MBR-style partitions where you have to actually copy data around the
disk (unless you only want to change the final partition).
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.
