System container image builder for LXC and LXD


Type Service Status
CI GitHub Build Status
Project status CII Best Practices CII Best Practices

Command line options

The following are the command line options of distrobuilder. You can use distrobuilder to create container images for both LXC and LXD.

$ distrobuilder
System container image builder for LXC and LXD

  distrobuilder [command]

Available Commands:
  build-dir      Build plain rootfs
  build-lxc      Build LXC image from scratch
  build-lxd      Build LXD image from scratch
  help           Help about any command
  pack-lxc       Create LXC image from existing rootfs
  pack-lxd       Create LXD image from existing rootfs
  repack-windows Repack Windows ISO with drivers included

      --cache-dir         Cache directory
      --cleanup           Clean up cache directory (default true)
      --debug             Enable debug output
      --disable-overlay   Disable the use of filesystem overlays
  -h, --help              help for distrobuilder
  -o, --options           Override options (list of key=value)
  -t, --timeout           Timeout in seconds
      --version           Print version number

Use "distrobuilder [command] --help" for more information about a command.

Installing from package

distrobuilder is available from the snapstore.

sudo snap install distrobuilder --classic

Installing from source

To compile distrobuilder from source, first install the Go programming language, and some other dependencies.

  • Debian-based: sudo apt update sudo apt install -y golang-go debootstrap rsync gpg squashfs-tools git
  • ArchLinux-based: sudo pacman -Syu sudo pacman -S go debootstrap rsync gnupg squashfs-tools git --needed

Second, download the source code of the distrobuilder repository (this repository).

git clone https://github.com/lxc/distrobuilder

Third, enter the directory with the source code of distrobuilder and run make to compile the source code. This will generate the executable program distrobuilder, and it will be located at $HOME/go/bin/distrobuilder.

cd ./distrobuilder

Finally, you can run distrobuilder as follows. You may also add to your $PATH the directory $HOME/go/bin/ so that you do not need to run the command with the full path.


How to use

In the following, we see how to create a container image for LXD.

Creating a container image

To create a container image, first create a directory where you will be placing the container images, and enter that directory.

mkdir -p $HOME/ContainerImages/ubuntu/
cd $HOME/ContainerImages/ubuntu/

Then, copy one of the example yaml configuration files for container images into this directory. In this example, we are creating an Ubuntu container image.

cp $HOME/go/src/github.com/lxc/distrobuilder/doc/examples/ubuntu.yaml ubuntu.yaml

Build the container image for LXD

Finally, run distrobuilder to create the container image. We are using the build-lxd option to create a container image for LXD.

sudo $HOME/go/bin/distrobuilder build-lxd ubuntu.yaml

If the command is successful, you will get an output similar to the following. The lxd.tar.xz file is the description of the container image. The rootfs.squasfs file is the root filesystem (rootfs) of the container image. The set of these two files is the container image.

$ ls -l
total 100960
-rw-r--r-- 1 root   root         676 Oct  3 16:15 lxd.tar.xz
-rw-r--r-- 1 root   root   103370752 Oct  3 16:15 rootfs.squashfs
-rw-r--r-- 1 ubuntu ubuntu      7449 Oct  3 16:03 ubuntu.yaml

Adding the container image to LXD

To add the container image to a LXD installation, use the lxc image import command as follows.

$ lxc image import lxd.tar.xz rootfs.squashfs --alias mycontainerimage
Image imported with fingerprint: 009349195858651a0f883de804e64eb82e0ac8c0bc51880

Let's see the container image in LXD. The ubuntu.yaml had a setting to create an Ubuntu 20.04 (focal) image. The size is 98.58MB.

$ lxc image list mycontainerimage
|      ALIAS       | FINGERPRINT  | PUBLIC | DESCRIPTION  |  ARCH  |  SIZE   |         UPLOAD DATE         |
| mycontainerimage | 009349195858 | no     | Ubuntu focal | x86_64 | 98.58MB | Oct 3, 2020 at 5:10pm (UTC) |

Launching a LXD container from the container image

To launch a container from the freshly created container image, use lxc launch as follows. Note that you do not specify a repository of container images (like ubuntu: or images:) because the image is located locally.

$ lxc launch mycontainerimage c1
Creating c1
Starting c1

Build a LXC container image

Using LXC containers instead of LXD may require the installation of lxc-utils. Having both LXC and LXD installed on the same system will probably cause confusion. Use of raw LXC is generally discouraged due to the lack of automatic Apparmor protection.

For LXC, instead use:

$ sudo $HOME/go/bin/distrobuilder build-lxc ubuntu.yaml
$ ls -l
total 87340
-rw-r--r-- 1 root root      740 Jan 19 03:15 meta.tar.xz
-rw-r--r-- 1 root root 89421136 Jan 19 03:15 rootfs.tar.xz
-rw-r--r-- 1 root root     4798 Jan 19 02:42 ubuntu.yaml

Adding the container image to LXC

To add the container image to a LXC installation, use the lxc-create command as follows.

lxc-create -n myContainerImage -t local -- --metadata meta.tar.xz --fstree rootfs.tar.xz

Then start the container with

lxc-start -n myContainerImage

Repack Windows ISO

With LXD it's possible to run Windows VMs. All you need is a Windows ISO and a bunch of drivers. To make the installation a bit easier, distrobuilder added the repack-windows command. It takes a Windows ISO, and repacks it together with the necessary drivers.

Currently, distrobuilder supports Windows 10, Windows Server 2012, Windows Server 2016, and Windows Server 2019. The Windows version will automatically be detected, but in case this fails you can use the --windows-version flag to set it manually. It supports the values w10, 2k12, 2k16, and 2k19 for Windows 10, Windows Server 2012, Windows Server 2016 and Windows Server 2019 respectively.

Here's how to repack a Windows ISO:

distrobuilder repack-windows path/to/Windows.iso path/to/Windows-repacked.iso

More information on repack-windows can be found by running

distrobuilder repack-windows -h

Install Windows

Run the following commands to initialize the VM, to configure (=increase) the allocated disk space and finally attach the full path of your prepared ISO file. Note that the installation of Windows 10 takes about 10GB (before updates), therefore a 30GB disk gives you about 20GB of free space.

lxc init win10 --empty --vm -c security.secureboot=false
lxc config device override win10 root size=30GiB
lxc config device add win10 iso disk source=/path/to/Windows-repacked.iso boot.priority=10

Now, the VM win10 has been configured and it is ready to be started. The following command starts the virtual machine and opens up a VGA console so that we go through the graphical installation of Windows.

lxc start win10 --console=vga

Taken from: https://blog.simos.info/how-to-run-a-windows-virtual-machine-on-lxd-on-linux/


Examples of yaml files for various distributions can be found in the examples directory and in the lxc-ci repository.


Error "Cannot install into target '/var/cache/distrobuilder.123456789/rootfs' mounted with noexec or nodev"

You have installed distrobuilder into a LXD container and you are trying to run it. distrobuilder does not run in a LXD container. Run distrobuilder on the host, or in a VM.

Error "error: This revision of snap "distrobuilder" was published using classic confinement"

You are trying to install the distrobuilder snap package. The distrobuilder snap package has been configured to use the classic confinement. Therefore, when you install it, you have to add the flag --classic as shown above in the instructions.

Error "You must be root to run this tool"

You must be root in order to run the distrobuilder tool. The tool runs commands such as mknod that require administrative privileges. Prepend sudo when running distrobuilder.