Libguestfs is a library for accessing and modifying guest disk images. Amongst the things this is good for: making batch configuration changes to guests, getting disk used/free statistics (see also: virt-df), migrating between virtualization systems (see also: virt-p2v), performing partial backups, performing partial guest clones, cloning guests and changing registry/UUID/hostname info, and much else besides. Libguestfs uses Linux kernel and qemu code, and can access any type of guest filesystem that Linux and qemu can, including but not limited to: ext2/3/4, btrfs, FAT and NTFS, LVM, many different disk partition schemes, qcow, qcow2, vmdk. Libguestfs provides ways to enumerate guest storage (eg. partitions, LVs, what filesystem is in each LV, etc.). It can also run commands in the context of the guest. Also you can access filesystems over FUSE. Libguestfs is a library that can be linked with C and C++ management programs (or management programs written in OCaml, Perl, Python, Ruby, Java, PHP, Haskell or C#). You can also use it from shell scripts or the command line. Libguestfs was written by Richard W.M. Jones (rjones@redhat.com) and hacked on by lots of other people. For discussion, development, patches, etc. please use the mailing list: http://www.redhat.com/mailman/listinfo/libguestfs Home page ---------------------------------------------------------------------- http://libguestfs.org/ Requirements ---------------------------------------------------------------------- - recent QEMU >= 0.12 with virtio-serial support - febootstrap >= 3.0 *NB*: febootstrap 2.x WILL NOT WORK febootstrap 3.x is distro-independent, and is required on Debian and other distros too - XDR, rpcgen (on Linux these are provided by glibc) - pcre (Perl Compatible Regular Expressions C library) (optional) - libmagic (the library that corresponds to the 'file' command) (optional) - libvirt (optional) - libxml2 (optional) - Augeas (http://augeas.net/) (optional) - gperf - squashfs-tools (mksquashfs only) - genisoimage / mkisofs - hivex >= 1.2.1 (http://libguestfs.org/download) - (Optional) Berkeley DB 'db_dump' and 'db_load' utilities (db4-utils or db4.X-util or similar) - (Optional) FUSE to build the FUSE module - perldoc (pod2man, pod2text, pod2html) to generate the manual pages and other documentation. - (Optional) Readline to have nicer command-line editing in guestfish. - (Optional) xmllint to validate virt-inspector RELAX NG schema - (Optional) OCaml if you want to rebuild the generated files, and also to build the OCaml bindings - (Optional) local Fedora mirror - (Optional) Perl if you want to build the perl bindings - (Optional) Python if you want to build the python bindings - (Optional) Ruby, rake if you want to build the ruby bindings - (Optional) Java, JNI, jpackage-utils if you want to build the java bindings - (Optional) GHC if you want to build the Haskell bindings - (Optional) Perl Sys::Virt module. - (Optional) Perl Win::Hivex module. - (Optional) Perl Pod::Usage module. - (Optional) Perl Test::More module (from perl Test::Simple). - (Optional) Perl String::ShellQuote module. - (Optional, but highly recommended) perl-libintl for translating perl code. - (Optional) po4a for translating manpages and POD files. - (Optional) PHP, phpize if you want to build the PHP bindings Running ./configure will check you have all the requirements installed on your machine. Building ---------------------------------------------------------------------- Then make the daemon, library and root filesystem: ./configure [--with-mirror=URI] make Use the optional --with-mirror parameter to specify the URI of a local Fedora mirror. See the discussion of the MIRROR parameter in the febootstrap(8) manpage. Finally run the tests: make check If everything works, you can install the library and tools by running this command as root: make install qemu ---------------------------------------------------------------------- By far the most common problem is with broken or incompatible qemu releases. Different versions of qemu have problems booting the appliance for different reasons. This varies between versions of qemu, and Linux distributions which add their own patches. If you find a problem, you could try using your own qemu built from source (qemu is very easy to build from source), with a 'qemu wrapper'. Qemu wrappers are described in the guestfs(3) manpage. Note on using KVM ---------------------------------------------------------------------- By default the configure script will look for qemu-kvm (KVM support). You will need a reasonably recent processor for this to work. KVM is much faster than using plain Qemu. You may also need to enable KVM support for non-root users, by following these instructions: http://www.linux-kvm.org/page/FAQ#How_can_I_use_kvm_with_a_non-privileged_user.3F On some systems, this will work too: chmod o+rw /dev/kvm On some systems, the chmod will not survive a reboot, and you will need to make edits to the udev configuration. vmchannel ---------------------------------------------------------------------- Previous versions of libguestfs required something called "vmchannel". Vmchannel is a special device given to virtual machines which allows them to communicate in some way with the host, often (but not always) without using a traditional network device. In reality, there is no one thing called "vmchannel". This idea has been reimplemented several times under the name vmchannel, and other hypervisors have their own incompatible implementation(s) too. In libguestfs <= 1.0.71, we required a specific vmchannel which is properly known as "guestfwd" and has been upstream in qemu since here: http://lists.gnu.org/archive/html/qemu-devel/2009-02/msg01042.html In libguestfs >= 1.0.71 we don't require any vmchannel implementation, as long as qemu has been compiled with support for SLIRP (user mode networking, or "-net user"), which is almost always the case. In libguestfs >= 1.5.4 we switched again to using qemu's virtio-serial and removed all the other vmchannels and the SLIRP channel. Supermin appliance ---------------------------------------------------------------------- In libguestfs >= 1.7.19 the supermin appliance is the default and only supported form of appliance. For more information see febootstrap (http://people.redhat.com/~rjones/febootstrap/). Mirroring tip ---------------------------------------------------------------------- On my machines I can usually rebuild the appliance in around 3 minutes. If it takes much longer for you, use a local Fedora mirror or squid. To use squid to cache yum downloads, read this first: https://lists.dulug.duke.edu/pipermail/yum/2006-August/009041.html (In brief, because yum chooses random mirrors each time, squid doesn't work very well with default yum configuration. To get around this, choose a Fedora mirror which is close to you, set this with './configure --with-mirror=[...]', and then proxy the whole lot through squid by setting http_proxy environment variable). You will also need to substantially increase the squid configuration limits: http://fedoraproject.org/wiki/Using_Mock_to_test_package_builds#Using_Squid_to_Speed_Up_Mock_package_downloads Porting to other Linux distros / non-Linux ---------------------------------------------------------------------- libguestfs itself should be fairly portable to other Linux distributions. Non-Linux ports are trickier, but we will accept patches if they aren't too invasive. The main porting issues are with the dependencies needed to build the appliance. You will need to port the febootstrap first (http://people.redhat.com/~rjones/febootstrap/). Copyright and license information ---------------------------------------------------------------------- Copyright (C) 2009-2010 Red Hat Inc. The library is distributed under the LGPLv2+. The programs are distributed under the GPLv2+. Please see the files COPYING and COPYING.LIB for full license information.