.. _image_types:

Image Types
===========

.. note::

   Before building an image with {kiwi}, it's important to understand
   the different image types and their meaning. This document provides
   an overview of the supported {kiwi} image types, their results,
   and some words about the environment to run the build.

ISO Hybrid Live Image
  An ISO image that can be dumped on a CD/DVD or USB stick
  and boots from this media without interfering with other
  system storage components. A useful pocket system for testing,
  demo, and debugging purposes. For further details, refer
  to :ref:`hybrid_iso`.

Virtual Disk Image
  An image representing the system disk, useful for cloud frameworks
  like Amazon EC2, Google Compute Engine, or Microsoft Azure.
  For further details, refer to :ref:`simple_disk`.

OEM Expandable Disk Image
  An image representing an expandable system disk. This means after
  deployment, the system can resize itself to the new disk geometry.
  The resize operation is configurable as part of the image description,
  and an installation image for CD/DVD, USB stick, and network deployment
  can be created in addition. For further details, refer to:
  :ref:`expandable_disk`.

Docker Container Image
  An archive image suitable for the Docker container engine.
  The image can be loaded via the `docker load` command and
  works within the scope of the container engine.
  For further details, refer to: :ref:`building_container_build`.

WSL Container Image
  An archive image suitable for the Windows Subsystem for Linux
  container engine. The image can be loaded from a Windows System
  that has support for WSL activated. For further details, refer
  to: :ref:`building_wsl_build`.

KIS Root Filesystem Image
  An optional root filesystem image associated with a kernel and initrd.
  The use case for this component image type is highly customizable.
  Many different deployment strategies are possible.
  For further details, refer to: :ref:`kis`.

AWS Nitro Enclave
  An initrd-based image using the `eif` binary format. The image is
  expected to be used in the AWS Nitro Enclave system or for testing
  in QEMU. For further details, refer to: :ref:`eif`.

Image Results
-------------

{kiwi} execution results in an appliance image after a successful run of
the :ref:`kiwi_system_build` or :ref:`kiwi_system_create` command.
The result is the image binary plus some additional metadata files
that are needed for image deployment and/or exist for informative
reasons. By default, the output files follow this naming convention:

`<image-name>.\<arch\>-\<version\>.\<extension\>`

where `<image-name>` is the name stated in the :ref:`image-description` as an
attribute of the :ref:`sec.image` element. The `<arch>` is the CPU
architecture used for the build, `<version>` is the image version defined in
the :ref:`<version><sec.preferences>` element of the image description,
and the `<extension>` is dependent on the image type and its definition.

Any {kiwi} appliance build results in, at least, the following output files:

1. The image binary, `<image-name>.\<arch\>-\<version\>.\<image-extension\>`:

   This is the file containing the actual image binary. Depending
   on the image type and its definition, it can be a virtual disk image
   file, an ISO image, a tarball, etc.

2. The `<image-name>.<arch>-<version>.packages` file:

   This file includes a sorted list of the packages
   that are included in the image. In fact, this is a normalized dump of the
   package manager database. It follows the following CSV format, where each
   line is represented by:

   `<name>|\<epoch\>|\<version\>|\<release\>|\<arch\>|\<disturl\>|\<license\>`

   The values represented here are mainly based on RPM packages' metadata.
   Other package managers may not provide all of these values. In such cases,
   the format is the same, and the fields that cannot be provided are set as
   `None`. This list can be used to track changes across multiple
   builds of the same image description over time by diffing the
   packages installed.

3. The `<image-name>.<arch>-<version>.verified` file:

   This file is the output of a verification done by the package manager
   against the package database. More specifically, it is the output of
   the `rpm` verification process or `dpkg` verification,
   depending on the packaging technology selected for the image.
   In both cases, the output follows the RPM verification syntax. This
   provides an overview of all package statuses right before any boot of
   the image.

Depending on the image type, the following output files exist:

image="tbz"
  For this image type, the result is mainly a root tree packed in a tarball:

  - **root archive**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.tar.xz`

image="btrfs|ext2|ext3|ext4|squashfs|xfs"
  The image root tree data is packed into a filesystem image of the given
  type; hence, the result for an `ext4` image would be:

  - **filesystem image**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.ext4`

image="iso"
  The image result is an ISO file:

  - **live image**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.iso`

image="oem"
  An image representing an expandable disk image. {kiwi} can also produce an
  installation ISO for this disk image by setting `installiso="true"` in
  the :ref:`\<preferences\>\<type\><sec.preferences>`) section or a tarball,
  including the artifacts for a network deployment, by setting `installpxe="true"`.
  For further details, see :ref:`expandable_disk`. The results for `oem`
  can be:

  - **disk image**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.raw`
  - **installation image (optional)**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.install.iso`
  - **installation pxe archive (optional)**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.install.tar`

  The disk image can also be provided in one of the various virtual disk
  formats, which can be specified in the `format` attribute of the
  :ref:`\<preferences\>\<type\><sec.preferences>` section. For further
  details, see :ref:`simple_disk`. The result for e.g., `format="qcow2"`
  would be:

  - **disk image**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.qcow2`

  instead of the `.raw` default disk format.

image="docker"
  An archive image suitable for the Docker container engine. The result is
  a loadable (`docker load -i <image>`) tarball:

  - **container**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.docker.tar.xz`

image="oci"
  An archive image that builds a container matching the OCI
  (Open Container Interface) standard. The result is a tarball matching OCI
  standards:

  - **container**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.oci.tar.xz`

image="appx"
  An archive image suitable for the Windows Subsystem for Linux
  container engine. The result is an `appx` binary file:

  - **container**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.appx`

image="wsl"
  An archive image suitable for the Windows Subsystem for Linux
  container engine >= v2.4.4. The result is a gzip-compressed tar
  archive with the `.wsl` extension:

  - **container**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.wsl`

image="kis"
  An optional root filesystem image associated with a kernel and initrd.
  All three binaries are packed in a tarball. See :ref:`kis` for further
  details about the kis archive:

  - **kis archive**:
    :file:`{exc_image_base_name}.x86_64-{exc_image_version}.tar.xz`

Image Bundle Format
-------------------

The result files as mentioned above are used in the {kiwi} result bundler.
The `kiwi-ng result bundle` command can be used to copy or package the
mandatory image files to create a customer release. In this process, it's
possible to apply a specific name pattern suitable for the requirements
of the release. A typical result bundle call can look like the following:

.. code:: bash

   $ kiwi-ng result bundle --target-dir /path/to/image/build_result \
         --bundle-dir=/path/to/image/release_result \
         --id=release_identifier

In this call, and depending on the image type, the required files as they
exist in :file:`/path/to/image/build_result` are copied to
:file:`/path/to/image/release_result/`. The only modification to the file
names is the `--id` information, which is appended with a `-` at the
end of the version substring. If we take
:file:`{exc_image_base_name}.x86_64-{exc_image_version}.iso` as an example.
This file would be bundled as
:file:`{exc_image_base_name}.x86_64-{exc_image_version}-release_identifier.iso`.

Depending on the use case and the customer requirements, this naming
schema and the default way the kiwi bundler processes the result files
is not appropriate. To allow for a more flexible naming schema when
bundling results, {kiwi} allows you to specify a bundle_format per type, like
in the following example:

.. code:: xml

   <type image="..." bundle_format="name_pattern">
       <!-- type definition -->
   </type>

The specified `name_pattern` is used as the base name for the image
files the bundler uses. As part of the `name_pattern`, the following
placeholders, which are replaced by their real value, can be used:

%N
  Turns into the contents of the `name` attribute of the `<image>` section.

%P
  Turns into the profile name used at build time of the image.
  If multiple profiles were used to build the image, the result
  name consists of the individual profile names concatenated
  by a `_` in the order of their specification in the image
  description and/or the command line.

%A
  Turns into the architecture name at build time of the image.
  Arch names are taken from Python's `platform.machine` information.

%I
  Turns into the identifier name given via the `--id` option at the
  call time of the bundler.

%T
  Turns into the contents of the `image` attribute of the `<type>` section.

%M
  Turns into the major number of the `<version>` section.

%m
  Turns into the minor number of the `<version>` section.

%p
  Turns into the patch number of the `<version>` section.

%v
  Turns into the version text of the `<version>` section.
