Use distrobuilder to create images#

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/ 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 file system (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, Windows Server 2019 and Windows Server 2022. 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, 2k19 and 2k22 for Windows 10, Windows Server 2012, Windows Server 2016, Windows Server 2019 and Windows Server 2022 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: 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.