X-Git-Url: http://git.annexia.org/?p=libguestfs.git;a=blobdiff_plain;f=README;h=d56d21ee77e9edf458320491b7266967c139f109;hp=a017249f3339712451c7e0d5dee09c5fc16afadf;hb=58e7e42033b1ac5044ae03f0aa5d5082c5fdb497;hpb=863d13ea1aadddc122ad82f4dad20e73231b48f2 diff --git a/README b/README index a017249..d56d21e 100644 --- a/README +++ b/README @@ -1,4 +1,4 @@ -libguestfs is a library for accessing and modifying guest disk images. +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: @@ -6,38 +6,79 @@ 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 +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, +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 mount guest filesystems on -the host (requires root privs and NFS). +in the context of the guest. Also you can access filesystems over FTP. -libguestfs is a library that can be linked with C and C++ management -programs (or management programs written in other languages, if people -contribute the language bindings). You can also use it from shell -scripts or the command line. +Libguestfs is a library that can be linked with C and C++ management +programs (or management programs written in OCaml, Perl, Python, Ruby, Java +or Haskell). You can also use it from shell scripts or the command line. -libguestfs was written by Richard W.M. Jones (rjones@redhat.com). -For discussion please use the fedora-virt mailing list: +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: - https://www.redhat.com/mailman/listinfo/fedora-virt + http://www.redhat.com/mailman/listinfo/libguestfs + + +Home page +---------------------------------------------------------------------- + + http://libguestfs.org/ Requirements ---------------------------------------------------------------------- -- recent QEMU with vmchannel support +- recent QEMU >= 0.10 with vmchannel support + http://lists.gnu.org/archive/html/qemu-devel/2009-02/msg01042.html + +- febootstrap >= 2.3 + +- fakeroot + +- fakechroot >= 2.9 + +- XDR, rpcgen (on Linux these are provided by glibc) + +- squashfs-tools (mksquashfs only) + +- (Optional) Augeas (http://augeas.net/) -- febootstrap >= 1.2 +- perldoc (pod2man, pod2text) to generate the manual pages and + other documentation. -- XDR, rpcgen +- (Optional) Readline to have nicer command-line editing in guestfish. + +- (Optional) 'reged' program from chntpw to decode Windows registry + entries (http://home.eunet.no/~pnordahl/ntpasswd/) + +- (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 XML::XPath, Sys::Virt modules (for libvirt support +in virt-inspector). + +- (Optional, but highly recommended) perl-libintl for translating perl code. + Running ./configure will check you have all the requirements installed on your machine. @@ -59,25 +100,197 @@ Finally run the tests: make check If everything works, you can install the library and tools by running -these commands as root: +this command as root: make install + +Fedora +---------------------------------------------------------------------- + +We provide packages for Fedora >= 11 in Fedora. Use those, or build +from our source RPMs - it's far simpler that way. + +You can compile libguestfs on Fedora 10 but you cannot use it with the +version of qemu in Fedora 10. You need to compile your own qemu, see +section 'qemu' below. + + +RHEL / EPEL / CentOS etc +---------------------------------------------------------------------- + +We provide packages in EPEL which cover RHEL/CentOS >= 5. Use those +or build from our source RPMs. + + +Debian +---------------------------------------------------------------------- + +libguestfs is now built as a package in Debian by Guido Gunther and +the other Debian libvirt maintainers. See: + +http://wiki.debian.org/Teams/DebianLibvirtTeam#Packages + +You can build for Debian in two different ways, either building a +Fedora-based appliance using febootstrap, yum, rpm, fakeroot, +fakechroot (all packaged in Debian). However the recommended way is +to build a Debian-based appliance using debootstrap and debirf. + +Both ways are supported by the configure script. + + +qemu +---------------------------------------------------------------------- + +By far the most common problem is with broken or incompatible +qemu releases. + +First of all, you need qemu >= 0.10.4, which contains a vmchannel +implementation. There are several, conflicting, incompatible things +called 'vmchannel' which at one time or another have been added or +proposed for qemu/KVM. The _only_ one we support is this one: + + http://lists.gnu.org/archive/html/qemu-devel/2009-02/msg01042.html + +Secondly, 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. + + +Supermin appliance +---------------------------------------------------------------------- + +If you configure with --enable-supermin then we will build a supermin +appliance (supermin = super-minimized). This is a very specialized +appliance which is built on-the-fly at runtime (specifically, when you +call guestfs_launch). + +The normal appliance is a self-contained Linux operating system, based +on the Fedora/RHEL/CentOS Linux distro. So it contains a complete +copy of all the libraries and programs needed, like kernel, libc, +bash, coreutils etc etc. + +The supermin appliance removes the kernel and all the executable +libraries and programs from the appliance. That just leaves a +skeleton of config files and some data files, which is obviously +massively smaller than the normal appliance. At runtime we rebuild +the appliance on-the-fly from the libraries and programs on the host +(eg. pulling in the real /lib/libc.so, the real /bin/bash etc.) + +Although this process of rebuilding the appliance each time sounds +slow, it turns out to be faster than using the prebuilt appliance. +(Most of the saving comes from not compressing the appliance - it +transpires that decompressing the appliance is the slowest part of the +whole boot sequence). On my machine, a new appliance can be built in +under a fifth of a second, and the boot time is several seconds +shorter. + +The big advantage of the supermin appliance for distributions like +Fedora is that it gets security fixes automatically from the host, so +there is no need to rebuild the whole of libguestfs for a security +update in some underlying library. + +There are several DISADVANTAGES: + +It won't work at all except in very narrow, controlled cases like the +Fedora packaging case. We control the dependencies of the libguestfs +RPM tightly to ensure that the required binaries are actually present +on the host. + +Furthermore there are certain unlikely changes in the packages on the +host which could break a supermin appliance, eg. an updated library +which depends on an additional data file. + +Also supermin appliances are subjected to changes in the host kernel +which might break compatibility with qemu -- these are, of course, +real bugs in any case. + +Lastly, supermin appliances really can't be moved between branches of +distributions (eg. built on Fedora 12 and moved to Fedora 10) because +they are not self-contained and they rely on certain libraries being +around. You shouldn't do this anyway. + +Use supermin appliances with caution. + + Notes on cross-architecture support ---------------------------------------------------------------------- At the moment we basically don't support cross-architecture or 32-on-64. This limits what is possible for some guests. Filesystem -operations and NFS export will work fine, but running commands in +operations and FTP export will work fine, but running commands in guests may not be possible. To enable this requires work for cross-architecture and 32-on-64 -support in febootstrap. +support in febootstrap, fakeroot and fakechroot. The daemon/ directory contains its own configure script. This is so that in future we will be able to cross-compile the daemon. +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 find or port the following packages +first: + + - fakeroot + - fakechroot + - python + - rpm-python http://www.rpm.org/ + - yum http://yum.baseurl.org/ + - febootstrap http://et.redhat.com/~rjones/febootstrap/ + + Copyright and license information ----------------------------------------------------------------------