.. _lxd-openstack-images: LXD and OpenStack images ======================== `LXD`_ is an open-source tool for orchestrating virtual machines and system containers. It is image based, and provides support for a large number of distributions and architectures. `OpenStack`_ is an open-source cloud platform designed to create and manage cloud resources. By aggregating physical resources such as distributed compute, network, and storage into a pool, OpenStack then allocates virtual resources on-demand to users out of this pool. It does not handle virtualisation itself, but acts as a wrapper that leverages existing virtualisation technologies. What are these images? ---------------------- Canonical provides cloud image artefacts on `cloud-images.ubuntu.com`_ that have been customised to run on public clouds, including LXD and OpenStack. To learn more about these artefacts and supported architectures, visit our Ubuntu :doc:`cloud image artefacts <../public-images-reference/artefacts>` documentation. How do you access them? ----------------------- Go to `cloud-images.ubuntu.com`_ and select a release. For the latest LTS release, Ubuntu 24.04 LTS Noble Numbat, you would navigate to ``noble > current``. Note that all artefacts are architecture specific, in the format ``--cloudimg--``. LXD and OpenStack also have `minimal cloud images`_: Ubuntu images that have a reduced runtime footprint, optimised kernel and boot process. They are smaller and boot faster, but are not designed for environments requiring human interaction or debugging. LXD images ~~~~~~~~~~ To import an image into LXD, you will need two artefacts: 1. A LXD tarball: - The :ref:`lxd-tarball-ref` artefact has the extension ``*.lxd.tar.xz`` - It contains the metadata needed by LXD to instantiate a container or virtual machine as well as a folder for any custom templates 2. A file system for a container or a bootable disk image for a virtual machine: - The file system for a container can be either a * :ref:`root-tarball-ref` (``*-root.tar.xz``), or a * :ref:`squashfs-ref` (``*.squashfs``) - The bootable disk image for a virtual machine is a :ref:`qcow-ref` image (``*.img``) The following are example commands to import an image for creating LXD containers and virtual machines based on downloaded Ubuntu 24.04 artefacts: .. code :: bash lxc image import noble-server-cloudimg-amd64-lxd.tar.xz \ noble-server-cloudimg-amd64-root.tar.xz --alias noble_container .. code :: bash lxc image import noble-server-cloudimg-amd64-lxd.tar.xz \ noble-server-cloudimg-amd64.img --alias noble_vm OpenStack images ~~~~~~~~~~~~~~~~ OpenStack uses QCOW images. Download the artefact for your chosen architecture with the ``*.img`` extension. Use the `OpenStack command-line client`_ to interact with OpenStack. An example of uploading an image looks something like this: .. code :: bash openstack image create “Ubuntu-24.04” \ --file noble-server-cloudimg-amd64.img \ --disk-format qcow2 \ --container-format bare \ --public To learn more about managing images with OpenStack, you can refer to the `Manage images`_ section of their documentation. How do you configure them? -------------------------- Configuring an Ubuntu cloud image allows you to make changes that tailor the image to your specific use case. You can automate the creation of user accounts, configure SSH access, or install software before the instance starts. LXD images ~~~~~~~~~~ You can configure your cloud images in LXD either before you import them or after. Configuring your images before importing them is most commonly done by editing the ``metadata.yaml`` file contained in the LXD tarball. Configuring your images after importing them is done through the CLI. If you are interested in configuration of LXD containers rather than images, take a look at the Ubuntu Server `LXD containers`_ documentation. Configuring metadata ^^^^^^^^^^^^^^^^^^^^ LXD metadata is stored in the ``metadata.yaml`` file in the LXD tarball. This file contains all of the information needed to run an image in LXD. To make changes to this file, you will have to: 1. Uncompress the LXD tarball. 2. Make modifications to the ``metadata.yaml`` file. See the `LXD image format`_ documentation to learn more about image metadata and the templates you may wish to modify. 3. Compress the metadata and templates. This snippet from the `How to customise LXD image metadata for cloud-init`_ guide referenced below demonstrates a typical workflow: .. code :: bash # Uncompress original LXD metadata $ tar xf ${RELEASE}-server-cloudimg-amd64-lxd.tar.xz # Add directives to create /etc/cloud/cloud.cfg.d/95-use-lxd.cfg $ cat > templates/cloud-init-use-lxd.tpl < add-lxd.yaml <> metadata.yaml # Compress LXD metadata and templates $ tar -czf ${RELEASE}-server-cloudimg-amd64-prefer-lxd.tar.xz metadata.yaml templates/ Configuring cloud-init ^^^^^^^^^^^^^^^^^^^^^^ `Cloud-init`_ is used to initialise cloud instances on first boot. Refer to `How to customise LXD image metadata for cloud-init`_ for a guide on configuring cloud-init for LXD before initialisation. If you want to configure ``cloud-init`` once an instance has been created (but not booted), refer to the `LXD docs on cloud-init`_. Configuring after import using CLI ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The `LXD documentation on images`_ has an extensive guide on managing images. Two of the most common use cases are to set individual properties or to edit all of the image properties. .. code :: bash # set a specific image property lxc image set-property .. code :: bash # edit the full image properties lxc image edit OpenStack images ~~~~~~~~~~~~~~~~ OpenStack has an extensive guide on `modifying images`_ that is applicable to the QCOW images Ubuntu provides. It leverages ``libguestfs`` `tools`_ in order to access and modify disk images. You can use the ``guestfish`` `interactive shell`_ (which exposes the full functionality of the ``guestfs`` API) or rely on the ``virt-*`` tools from ``libguestfs`` to perform specific tasks. For instance, use ``virt-cat`` for displaying files, ``virt-df`` for checking free space and ``virt-inspector`` for inspecting VM images. .. Links .. _LXD: https://canonical.com/lxd .. _OpenStack: https://ubuntu.com/openstack .. _cloud-images.ubuntu.com: https://cloud-images.ubuntu.com/ .. _minimal cloud images: https://cloud-images.ubuntu.com/minimal/ .. _OpenStack command-line client: https://docs.openstack.org/ocata/admin-guide/common/cli-install-openstack-command-line-clients.html .. _Manage images: https://docs.openstack.org/ocata/admin-guide/common/cli-manage-images.html#create-or-update-an-image-glance .. _LXD containers: https://documentation.ubuntu.com/server/how-to/containers/lxd-containers/ .. _LXD image format: https://documentation.ubuntu.com/lxd/en/latest/reference/image_format/ .. _How to customise LXD image metadata for cloud-init: https://discourse.ubuntu.com/t/how-to-customize-lxd-image-metadata-for-cloud-init/25157 .. _Cloud-init: https://cloudinit.readthedocs.io/en/latest/index.html .. _LXD docs on cloud-init: https://documentation.ubuntu.com/lxd/en/latest/cloud-init/ .. _LXD documentation on images: https://documentation.ubuntu.com/lxd/en/latest/howto/images_manage/ .. _modifying images: https://docs.openstack.org/image-guide/modify-images.html .. _tools: https://libguestfs.org/ .. _interactive shell: https://libguestfs.org/guestfish.1.html