LXD is a container hypervisor providing a ReST API to manage LXC containers.
This tutorial will show how to create a custom LXD image based on a basic Debian (or Debian-based distribution like Ubuntu) installation, to use locally or to publish.
- Ubuntu 16.04 or newer
- You should know how to create and launch an LXD/LXC container
Originally authored by Marcin Mikołajczak
Install required packages
To create minimal Debian system in specified directory from existing Linux installation, we will use debootstrap. Install it using:
sudo apt install debootstrap
We assume that you have already installed and configured LXD. If not, complete the “Setting up LXD on Ubuntu 16.04” tutorial.
Creating basic system installation
Installing Debian with debootstrap
After installing debootstrap, we can create a minimal installation of Debian in a specified directory. The command takes two arguments: the release to create and the target directory . To install Debian Sid (unstable) in new temporary directory:
mkdir /tmp/sid-lxd sudo debootstrap sid /tmp/sid-lxd
ⓘ You can specify a mirror as a third argument to install another Debian-based distribution. For example, to install Ubuntu Artful, use
sudo debootstrap artful /tmp/somewhere http://archive.ubuntu.com/ubuntu/.
sudo chroot /tmp/sid-lxd wget -qO- https://deb.nodesource.com/gpgkey/nodesource.gpg.key | apt-key add - echo 'deb https://deb.nodesource.com/node_8.x sid main' > /etc/apt/sources.list.d/nodesource.list echo 'deb-src https://deb.nodesource.com/node_8.x sid main' >> /etc/apt/sources.list.d/nodesource.list exit
Compressing system root directory in .tar.gz file.
If everything worked fine, create a compressed tarball of the root directory of your newly installed system:
sudo tar -cvzf rootfs.tar.gz -C /tmp/sid-lxd .
Creating a metadata file
metadata.yaml file describes things like image creation date, name, architecture and description. To create an LXD image, we need to provide such a file. Here’s an example of how simple metadata file should look:
architecture: "x86_64" creation_date: 1458040200 # To get current date in Unix time, use `date +%s` command properties: architecture: "x86_64" description: "Debian Unstable (sid) with preconfigured Node.js repository (20171227)" os: "debian" release: "sid"
Creating a tarball from the metadata file
After creating metadata file, we need to create tarball containing this file:
tar -cvzf metadata.tar.gz metadata.yaml
Now, it’s time for importing our new LXD image!
Importing LXD images
After creating them, let’s import our two tarballs as LXD images:
lxc image import metadata.tar.gz rootfs.tar.gz --alias sid-nodejs
We can now create a new container from this image:
lxc launch sid-nodejs tutorial lxc exec tutorial bash
You can verify whether our container uses Node.js repository with
sudo apt update && sudo apt-cache show nodejs. The
nodejs package should contain
1nodesource1 in “Version”.
Making images public
Configuring the LXD daemon
The LXD daemon works as an image server. In order to use it, we have to make LXD listen to the network and tag our image as public:
lxc config set core.https_address "[::]:8443"
Now, other users can add our server as a public image server using:
lxc remote add [name] [IP] --public
They can use following command to create containers from our image:
lxc launch [name]:[image-name]
Making LXD images public
To make our LXD image available for our server users, we have to modify the
public parameter, it’s
false by default:
lxc image edit sid-nodejs
It will open image properties in system default text editor. Replace
false in the last line with
true and save the file. You have just shared your LXD image!
Now you should know how to create LXD images and use LXD daemon to share them with others.
If you’d like to know more about LXD, take a look at the following resources:
Also, if you have questions or need help, you can find direct help here: