Tag Archives: libguestfs

Dockerfile for running libguestfs, virt-tools and virt-v2v

FROM fedora
RUN dnf install -y libguestfs libguestfs-tools-c virt-v2v \
                   libvirt-daemon libvirt-daemon-config-network

# https://bugzilla.redhat.com/show_bug.cgi?id=1045069
RUN useradd -ms /bin/bash v2v
USER v2v
WORKDIR /home/v2v

# This is required for virt-v2v because neither systemd nor
# root libvirtd runs, and therefore there is no virbr0, and
# therefore virt-v2v cannot set up the network through libvirt.
ENV LIBGUESTFS_BACKEND direct
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libguestfs for RHEL 7.5 preview

As usual I’ve placed the proposed RHEL 7.5 libguestfs packages in a public repository so you can try them out.

Thanks to Pino Toscano for doing the packaging work.

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Great new changes coming to nbdkit

Eric Blake has been doing some great stuff for nbdkit, the flexible plugin-based NBD server.

  • Full parallel request handling.
    You’ve always been able to tell nbdkit that your plugin can handle multiple requests in parallel from a single client, but until now that didn’t actually do anything (only parallel requests from multiple clients worked).
  • An NBD forwarding plugin, so if you have another NBD server which doesn’t support a feature like encryption or new-style protocol, then you can front that server with nbdkit which does.

As well as that he’s fixed lots of small bugs with NBD compliance so hopefully we’re now much closer to the protocol spec (we always check that we interoperate with qemu’s nbd client, but it’s nice to know that we’re also complying with the spec). He also fixed a potential DoS where nbdkit would try to handle very large writes which would delay a thread in the server indefinitely.


Also this week, I wrote an nbdkit plugin for handling the weird Xen XVA file format. The whole thread is worth reading because 3 people came up with 3 unique solutions to this problem.

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Fedora 27 virt-builder images

Fedora 27 has just been released, and I’ve just uploaded virt-builder images so you can try it right away:

$ virt-builder -l | grep fedora-27
fedora-27                aarch64    Fedora® 27 Server (aarch64)
fedora-27                armv7l     Fedora® 27 Server (armv7l)
fedora-27                i686       Fedora® 27 Server (i686)
fedora-27                ppc64      Fedora® 27 Server (ppc64)
fedora-27                ppc64le    Fedora® 27 Server (ppc64le)
fedora-27                x86_64     Fedora® 27 Server
$ virt-builder fedora-27 \
      --root-password password:123456 \
      --install emacs \
      --selinux-relabel \
      --size 30G
$ qemu-system-x86_64 \
      -machine accel=kvm:tcg \
      -cpu host -m 2048 \
      -drive file=fedora-27.img,format=raw,if=virtio &

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Tip: Changing the qemu product name in libguestfs

20:30 < koike> Hi. Is it possible to configure the dmi codes for libguestfs? I mean, I am running cloud-init inside a libguestfs session (through python-guestfs) in GCE, the problem is that cloud-init reads /sys/class/dmi/id/product_name to determine if the machine is a GCE machine, but the value it read is Standard PC (i440FX + PIIX, 1996) instead of the expected Google Compute Engine so cloud-init fails.

The answer is yes, using the guestfs_config API that lets you set arbitrary qemu parameters:

g.config('-smbios',
         'type=1,product=Google Compute Engine')

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Fedora 26 is out, virt-builder images available

Fedora 26 is released today. virt-builder images are already available for almost all architectures:

$ virt-builder -l | grep fedora-26
fedora-26                aarch64    Fedora® 26 Server (aarch64)
fedora-26                armv7l     Fedora® 26 Server (armv7l)
fedora-26                i686       Fedora® 26 Server (i686)
fedora-26                ppc64      Fedora® 26 Server (ppc64)
fedora-26                ppc64le    Fedora® 26 Server (ppc64le)
fedora-26                x86_64     Fedora® 26 Server

For example:

$ virt-builder fedora-26
$ qemu-system-x86_64 -machine accel=kvm:tcg -cpu host -m 2048 \
    -drive file=fedora-26.img,format=raw,if=virtio

Why not s390x? That’s because qemu doesn’t yet emulate enough of the s390x instruction set / architecture so that we can run Fedora under TCG emulation.

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virt-builder Debian 9 image available

Debian 9 (“Stretch”) was released last week and now it’s available in virt-builder, the fast way to build virtual machine disk images:

$ virt-builder -l | grep debian
debian-6                 x86_64     Debian 6 (Squeeze)
debian-7                 sparc64    Debian 7 (Wheezy) (sparc64)
debian-7                 x86_64     Debian 7 (Wheezy)
debian-8                 x86_64     Debian 8 (Jessie)
debian-9                 x86_64     Debian 9 (stretch)

$ virt-builder debian-9 \
    --root-password password:123456
[   0.5] Downloading: http://libguestfs.org/download/builder/debian-9.xz
[   1.2] Planning how to build this image
[   1.2] Uncompressing
[   5.5] Opening the new disk
[  15.4] Setting a random seed
virt-builder: warning: random seed could not be set for this type of guest
[  15.4] Setting passwords
[  16.7] Finishing off
                   Output file: debian-9.img
                   Output size: 6.0G
                 Output format: raw
            Total usable space: 3.9G
                    Free space: 3.1G (78%)

$ qemu-system-x86_64 \
    -machine accel=kvm:tcg -cpu host -m 2048 \
    -drive file=debian-9.img,format=raw,if=virtio \
    -serial stdio

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