The Image Description¶
The image description is a XML file that defines properties of the appliance that will be build by KIWI, for example:
image type (e.g. QEMU disk image, PXE bootable image, Vagrant box, etc.)
packages to be installed on the system
users to be added
We will follow the standard nomenclature when addressing components of the XML file:
An element is a XML “tag”:
<example/>, which we address by the name example.
Elements can have attributes which take values:
<example attr1="val1" attr2=val2"/>.
Elements can have children:
<element> <child/> </element>
Some elements have a content:
<element_with_content>CONTENT, while others are emtpy-element tags:
The image description consists of the root element
image and its
children, for example:
<?xml version="1.0" encoding="utf-8"?> <image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- all settings belong here --> </image>
image element requires the following two attributes (as shown in the
name: A name for this image that must not contain spaces or
schemaversion: The used version of the [KIWI] RNG schema. KIWI will automatically convert your image description from an older schema version to the most recent one (it will perform this only internally and won’t modify your
config.xml). If in doubt, use the latest schema version.
name attribute will be used to create the bootloader entry, however
it can be inconvenient to use as it must be POSIX-safe. You can therefore
provide an alternative name that will be displayed in the bootloader via
displayName, which doesn’t have the same strict rules as
name (it can contain spaces and slashes):
<?xml version="1.0" encoding="utf-8"?> <image schemaversion="7.1" name="LimeJeOS-Leap-15.1" displayName="LimeJeOS-Leap-15.1"> <!-- all setting belong here --> </image>
description element, contains some high level information about the
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <description type="system"> <author>Jane Doe</author> <contact>email@example.com</contact> <specification> LimeJeOS-Leap-15.1, a small image </specification> <license>GPLv3</license> </description> <!-- snip --> </image>
description element must always contain a
type attribute. This
attribute accepts the values
boot. The value
boot is used
by the KIWI developers and is not relevant for the end user, thus
should be always set to
description allows the following optional children:
author: The name of the author of this image.
contact: Some means how to contact the author of the image (e.g. an email address, an IM nickname and network, etc.)
specification: A detailed description of this image, e.g. its use case.
license: If applicable, you can specify a license for the image.
preferences element contains the definition of the various
enabled image types (so-called build types). Each of these build types can
be supplied with attributes specific to that image type, which we described
in the section Build Types.
The elements that are not image type specific are presented afterwards in section Common Elements.
A build type defines the type of an appliance that is produced by KIWI, for instance, a live ISO image or a virtual machine disk.
For example, a live ISO image is specified as follows:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <preferences> <type image="iso" primary="true" flags="overlay" hybridpersistent_filesystem="ext4" hybridpersistent="true"/> <!-- additional preferences --> </preferences> <!-- additional image settings --> </image>
A build type is defined via a single
type element whose only required
image, that defines which image type is created. All other
attributes are optional and can be used to customize an image further. In
the above example we created an ISO image, with the an ext4 filesystem
It is possible to provide multiple
type elements with different
image attributes inside the preferences section. The following XML
snippet can be used to create a live image, an OEM installation image, and
a virtual machine disk of the same appliance:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <preferences> <!-- Live ISO --> <type image="iso" primary="true" flags="overlay" hybridpersistent_filesystem="ext4" hybridpersistent="true"/> <!-- Virtual machine --> <type image="vmx" filesystem="ext4" bootloader="grub2" kernelcmdline="splash" firmware="efi"/> <!-- OEM installation image --> <type image="oem" filesystem="ext4" initrd_system="dracut" installiso="true" bootloader="grub2" kernelcmdline="splash" firmware="efi"> <oemconfig> <oem-systemsize>2048</oem-systemsize> <oem-swap>true</oem-swap> <oem-device-filter>/dev/ram</oem-device-filter> <oem-multipath-scan>false</oem-multipath-scan> </oemconfig> <machine memory="512" guestOS="suse" HWversion="4"/> </type> <!-- additional preferences --> </preferences> <!-- additional image settings --> </image>
Note the additional attribute
primary in the Live ISO image build
type. KIWI will by default build the image which
primary attribute is set
KIWI supports the following values for the
image attribute (further
attributes of the
type element are documented inside the referenced
iso: a live ISO image, see Build an ISO Hybrid Live Image
vmx: build a virtual machine image, see: Build a Virtual Disk Image
oem: results in an expandable image that can be deployed via a bootable installation medium, e.g. a USB drive or a CD. See Build an OEM Expandable Disk Image
pxe: creates an image that can be booted via PXE (network boot), see Build a PXE Root File System Image
oci: container images, see Build a Docker Container Image
xfs: KIWI will convert the image into a mountable filesystem of the specified type.
clicfs: creates the image as a filesystem that can be used in live systems
type element furthermore supports the following subelements (as shown
oemconfig is a subelement of
<type image="oem" ...>):
containerconfig: contains settings specific for the creation of container images, see Build a Docker Container Image
oemconfig: configurations relevant for building OEM images, see: Build an OEM Expandable Disk Image
pxedeploy: settings for PXE booting, see Build a PXE Root File System Image
vagrantconfig: instructs KIWI to build a Vagrant box instead of a standard virtual machine image, see KIWI Image Description for Vagrant
systemdisk: used to define LVM or Btrfs (sub)volumens, see Custom Disk Volumes
machine: for configurations of the virtual machines, see Customizing the Virtual Machine
size: for adjusting the size of the final image, see Modifying the Size of the Image.
type element supports a plethora of optional attributes, some of
these are only relevant for certain build types and will be covered in the
appropriate place. Certain attributes are however useful for nearly all
build types and will be covered here:
bootloader: Specifies the bootloader used for booting the image. At the moment
grub2_s390x_emu(a combination of zipl and a userspace GRUB2) are supported. The special
customentry allows to skip the bootloader configuration and installation and leaves this up to the user which can be done by using the
boottimeout: Specifies the boot timeout in seconds prior to launching the default boot option. By default the timeout is set to 10 seconds. It makes sense to set this value to
0for images intended to be started non-interactively (e.g. virtual machines).
bootpartition: Boolean parameter notifying KIWI whether an extra boot partition should be used or not (the default depends on the current layout). This will override KIWI’s default layout.
btrfs_quota_groups: Boolean parameter to activate filesystem quotas if the filesystem is
btrfs. By default quotas are inactive.
btrfs_root_is_snapshot: Boolean parameter that tells KIWI to install the system into a btrfs snapshot. The snapshot layout is compatible with snapper. By default snapshots are turned off.
btrfs_root_is_readonly_snapshot: Boolean parameter notifying KIWI that the btrfs root filesystem snapshot has to made read-only. if this option is set to true, the root filesystem snapshot it will be turned into read-only mode, once all data has been placed to it. The option is only effective if
btrfs_root_is_snapshotis also set to true. By default the root filesystem snapshot is writable.
compressed: Specifies whether the image output file should be compressed or not. This option is only used for filesystem only images or for the
editbootconfig: Specifies the path to a script which is called right before the bootloader is installed. The script runs relative to the directory which contains the image structure.
editbootinstall: Specifies the path to a script which is called right after the bootloader is installed. The script runs relative to the directory which contains the image structure.
filesystem: The root filesystem, the following file systems are supported:
firmwareSpecifies the boot firmware of the appliance, supported options are:
opal. This attribute is used to differentiate the image according to the firmware which boots up the system. It mostly impacts the disk layout and the partition table type. By default
biosis used on x86,
ofwon PowerPC and
force_mbr: Boolean parameter to force the usage of a MBR partition table even if the system would default to GPT. This is occasionally required on ARM systems that use a EFI partition layout but which must not be stored in a GPT. Note that forcing a MBR partition table incurs limitations with respect to the number of available partitions and their sizes.
fsmountoptions: Specifies the filesystem mount options which are passed via the
-oflag to mount and are included in
fscreateoptions: Specifies the filesystem options used to create the filesystem. In KIWI the filesystem utility to create a filesystem is called without any custom options. The default options are filesystem specific and are provided along with the package that provides the filesystem utility. For the Linux
extfilesystem, the default options can be found in the
/etc/mke2fs.conffile. Other filesystems provides this differently and documents information about options and their defaults in the respective manual page, e.g man mke2fs. With the
fscreateoptionsattribute it’s possible to directly influence how the filesystem will be created. The options provided as a string are passed to the command that creates the filesystem without any further validation by KIWI. For example, to turn off the journal on creation of an ext4 filesystem the following option would be required:
<type fscreateoptions="-O ^has_journal"/>
kernelcmdline: Additional kernel parameters passed to the kernel by the bootloader.
luks: Supplying a value will trigger the encryption of the partitions using the LUKS extension and using the provided string as the password. Note that the password must be entered when booting the appliance!
primary: Boolean option, KIWI will by default build the image which
primaryattribute is set to
target_blocksize: Specifies the image blocksize in bytes which has to match the logical blocksize of the target storage device. By default 512 Bytes is used, which works on many disks. You can obtain the blocksize from the
SSZcolumn in the output of the following command:
blockdev --report $DEVICE
Now that we have covered the
type element, we shall return to the
remaining child-elements of
version: A version number of this image. We recommend to use the following format: Major.Minor.Release, however other versioning schemes are possible, e.g. one can use the version of the underlying operating system.
packagemanager: Specify the package manager that will be used to download and install the packages for your appliance. Currently the following package managers are supported:
dnf. Note that the package manager must be installed on the system calling KIWI, it is not sufficient to install it inside the appliance.
locale: Specify the locale that the resulting appliance will use.
timezone: Override the default timezone of the image to a more suitable value, e.g. the timezone in which the image’s users reside.
rpm-check-signatures: Boolean value that defines whether the signatures of the downloaded RPM packages will be verified before installation. Note that when building appliances for a different distribution you will have to either import the other distribution’s signing-key or set this to
false(RPM will otherwise fail to verify the package signatures, as it does will not trust the signature key of other distributions or even other versions of the same distribution).
rpm-excludedocs: Boolean value that instructs RPM whether to install documentation with packages or not. Please bear in mind that enabling this can have quite a negative impact on user-experience and should thus be used with care.
bootsplash-theme: themes for the bootloader and the bootsplash-screen. These themes have to be either built-in to the bootloader or installed via the
An example excerpt from a image description using these child-elements of
preferences, results in the following image description:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- snip --> <preferences> <version>15.0</version> <packagemanager>zypper</packagemanager> <locale>en_US</locale> <keytable>us</keytable> <timezone>Europe/Berlin</timezone> <rpm-excludedocs>true</rpm-excludedocs> <rpm-check-signatures>false</rpm-check-signatures> <bootsplash-theme>openSUSE</bootsplash-theme> <bootloader-theme>openSUSE</bootloader-theme> <type image="vmx" filesystem="ext4" format="qcow2" boottimeout="0" bootloader="grub2"> </preferences> <!-- snip --> </image>
In the previous section we have covered build types, that are represented
in the image description as the
type element. We have also shown how it
is possible to include multiple build types in the same
appliance. Unfortunately that approach has one significant limitation: one
can only include multiple build types with different settings for the
In certain cases this is undesirable, for instance when building multiple
very similar virtual machine disks. Then one would have to duplicate the
config.xml for each virtual machine. KIWI supports profiles
to work around this issue.
A profile is a namespace for additional settings that can be applied by KIWI on top of the default settings (or other profiles), thereby allowing to build multiple appliances with the same build type but with different configurations.
In the following example, we create two virtual machine images: one for
QEMU (using the
qcow2 format) and one for VMWare (using the
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- snip --> <profiles> <profile name="QEMU" description="virtual machine for QEMU"/> <profile name="VMWare" description="virtual machine for VMWare"/> </profiles> <preferences> <version>15.0</version> <packagemanager>zypper</packagemanager> </preferences> <preferences profiles="QEMU"> <type image="vmx" format="qcow2" filesystem="ext4" bootloader="grub2"> </preferences> <preferences profiles="VMWare"> <type image="vmx" format="vmdk" filesystem="ext4" bootloader="grub2"> </preferences> <!-- snip --> </image>
Each profile is declared via the element
profile, which itself must be a
profiles and must contain the
description is only present for documentation purposes,
name on the other hand is used to instruct KIWI which profile to build
via the command line. Additionally, one can provide the boolean attribute
import, which defines whether this profile should be used by default when
KIWI is invoked via the command line.
A profile inherits the default settings which do not belong to any
profile. It applies only to elements that contain the profile in their
profiles attribute. The attribute
profiles expects a comma separated
list of profiles for which the settings of this element apply. The
attribute is present in the following elements only:
packages(see Defining Repositories and Adding or Removing Packages)
Profiles can furthermore inherit settings from another profile via the
<profiles> <profile name="VM" description="virtual machine"/> <profile name="QEMU" description="virtual machine for QEMU"> <requires>VM</requires> </profile> </profiles>
QEMU would inherit the settings from
VM in the above
We cover the usage of profiles when invoking KIWI and when building in the Open Build Service in Building Images with Profiles.
User accounts can be added or modified via the
users element, which
supports a list of multiple
user child elements:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <users> <user password="this_is_soo_insecure" home="/home/me" name="me" groups="users" pwdformat="plain" /> <user password="$1$wYJUgpM5$RXMMeASDc035eX.NbYWFl0" home="/root" name="root" groups="root" /> </users> </image>
user element represents a specific user that is added or
modified. The following attributes are mandatory:
name: the UNIX username
home: the path to the user’s home directory
Additionally, the following optional attributes can be specified:
groups: A comma separated list of UNIX groups. The first element of the list is used as the user’s primary group. The remaining elements are appended to the user’s supplementary groups. When no groups are assigned then the system’s default primary group will be used.
id: The numeric user id of this account.
pwdformat: The format in which
passwordis provided, either
encrypted(the latter is the default).
password: The password for this user account. It can be provided either in cleartext form (
pwdformat="plain") or in
crypt’ed form (
pwdformat="encrypted"). Plain passwords are discouraged, as everyone with access to the image description would know the password. It is recommended to generate a hash of your password, e.g. using the
mkpasswdtool (available in most Linux distributions via the
$ mkpasswd -m sha-512 -S $(date +%N) -s <<< INSERT_YOUR_PASSWORD_HERE
users element furthermore accepts a list of profiles (see
Image Profiles) to which it applies via the
profiles attribute, as shown in the following example:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <profiles> <profile name="VM" description="standard virtual machine"/> <profile name="shared_VM" description="virtual machine shared by everyone"/> </profiles> <!-- snip --> <users> <user password="$1$wYJUgpM5$RXMMeASDc035eX.NbYWFl0" home="/root" name="root" groups="root" /> </users> <users profiles="VM"> <user password="$1$blablabl$FRTFJZxMPfM6LA1g0EZ5h1" home="/home/devel" name="devel" /> </users> <users profiles="shared_VM"> <user password="super_secr4t" pwdformat="plain" home="/share/devel" name="devel" groups="users,devel" /> </users> </image>
Here the settings for the root user are shared among all appliances. The
configuration of the
devel user on the other hand depends on the profile.
Defining Repositories and Adding or Removing Packages¶
A crucial part of each appliance is the package and repository
selection. KIWI allows the end user to completely customize the selection
of repositories and packages via the
KIWI installs packages into your appliance from the repositories defined in the image description. Therefore at least one repository must be defined, as KIWI will otherwise not be able to fetch any packages.
A repository is added to the description via the
which is a child of the top-level
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- snip --> <repository type="rpm-md" alias="kiwi" priority="1"> <source path="obs://Virtualization:Appliances:Builder/openSUSE_Leap_15.1"/> </repository> <repository type="rpm-md" alias="OS" imageinclude="true"> <source path="obs://openSUSE:Leap:15.1/standard"/> </repository> </image>
In the above snippet we defined two repositories:
The repository belonging to the KIWI project: obs://Virtualization:Appliances:Builder/openSUSE_Leap_15.1 at the Open Build Service (OBS)
The RPM repository belonging to the OS project: obs://openSUSE:Leap:15.1/standard, at the Open Build Service (OBS). The translated http URL will also be included in the final appliance.
repository element accepts one
source child element, which
contains the URL to the repository in an appropriate format and the
following optional attributes:
type: repository type, accepts one of the following values:
rpm-md. For ordinary RPM repositories use
rpm-md, for ordinary APT repositories
imageinclude: Specify whether this repository should be added to the resulting image, defaults to false.
imageonly: A repository with
imageonly="true"will not be available during image build, but only in the resulting appliance. Defaults to false.
priority: An integer priority for all packages in this repository. If the same package is available in more than one repository, then the one with the highest priority is used.
alias: Name to be used for this repository, it will appear as the repository’s name in the image, which is visible via
dnf repolist. KIWI will construct an alias from the path in the
sourcechild element (replacing each
_), if no value is given.
repository_gpgcheck: Specify whether or not this specific repository is configured to to run repository signature validation. If not set, the package manager’s default is used.
package_gpgcheck: Boolean value that specifies whether each package’s GPG signature will be verified. If omitted, the package manager’s default will be used
components: Distribution components used for
debrepositories, defaults to
distribution: Distribution name information, used for deb repositories.
profiles: List of profiles to which this repository applies.
Supported repository paths¶
The actual location of a repository is specified in the
repository via its only attribute
path. KIWI supports the
following paths types:
ftp://URL: a URL to the repository available via HTTP(s) or FTP.
obs://$PROJECT/$REPOSITORY: evaluates to the repository
$REPOSITORYof the project
$PROJECTavailable on the Open Build Service (OBS). By default KIWI will look for projects on build.opensuse.org, but this can be overridden using the runtime configuration file (see The Runtime Configuration File). Note that it is not possible to add repositories using the
obs://path from different OBS instances (use direct URLs to the
.repofile instead in this case).
obsrepositories:/: special path only available for builds using the Open Build Service. The repositories configured for the OBS project in which the KIWI image resides will be available inside the appliance. This allows you to configure the repositories of your image from OBS itself and not having to modify the image description.
file:///path/to/file: an absolute path to a local directory or file available on the host building the appliance.
iso:///path/to/image.iso: the specified ISO image will be mounted during the build of the KIWI image and a repository will be created pointing to the mounted ISO.
Adding and removing packages¶
Now that we have defined the repositories, we can define which packages
should be installed on the image. This is achieved via the
element which includes the packages that should be installed, ignore or
removed via individual
package child elements:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <packages type="bootstrap"> <package name="udev"/> <package name="filesystem"/> <package name="openSUSE-release"/> <!-- additional packages installed before the chroot is created --> </packages> <packages type="image"> <package name="patterns-openSUSE-base"/> <!-- additional packages to be installed into the chroot --> </packages> </image>
packages element provides a collection of different child elements
that instruct KIWI when and how to perform package installation or
packages element acts as a group, whose behavior can be
configured via the following attributes:
uninstallor one of the following build types:
type="bootstrap"are pre-installed to populate the images’ root file system before chrooting into it.
type="image"are installed immediately after the initial chroot into the new root file system.
type="uninstall"are removed from the image, for details see Uninstall System Packages.
And packages which belong to a build type are only installed when that specific build type is currently processed by KIWI.
profiles: a list of profiles to which this package selection applies (see Image Profiles).
patternType: selection type for patterns, supported values are:
plusRecommended, see: The product and namedCollection element.
We will describe the different child elements of
packages in the following
package element represents a single package to be installed (or
removed), whose name is specified via the mandatory
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- snip --> <packages type="bootstrap"> <package name="udev"/> </packages> </image>
which adds the package
udev to the list of packages to be added to the
Packages can also be included only on specific architectures via the
attribute. KIWI compares the
arch attributes value with the output of
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- snip --> <packages type="image"> <package name="grub2"/> <package name="grub2-x86_64-efi" arch="x86_64"/> <package name="shim" arch="x86_64"/> </packages> </image>
which results in
shim being only installed on 64
Bit images, but GRUB2 also on 32 Bit images.
It is sometimes necessary to include additional packages into the image
which are not available in the package manager’s native format. KIWI
supports the inclusion of ordinary archives via the
name attribute specifies the filename of the archive (KIWI looks
for the archive in the image description folder).
<packages type="image"> <archive name="custom-program1.tgz"/> <archive name="custom-program2.tar"/> </packages>
KIWI will extract the archive into the root directory of the image using
GNU tar, thus only archives
supported by it can be included. When multiple
archive elements are
specified then they will be applied in a top to bottom order. If a file is
already present in the image, then the file from the archive will overwrite
it (same as with the image overlay).
Uninstall System Packages¶
KIWI supports two different methods how packages can be removed from the appliance:
Packages present as a child element of
<packages type="uninstall">will be gracefully uninstalled by the package manager alongside with dependent packages and orphaned dependencies.
Packages present as a child element of
<packages type="delete">will be removed by RPM/DPKG without any dependency check, thus potentially breaking dependencies and compromising the underlying package database.
uninstall packages request deletes:
the listed packages,
the packages dependent on the listed ones, and
any orphaned dependency of the listed packages.
Use this feature with caution as it can easily cause the removal of sensitive tools leading to failures in later build stages.
Removing packages via
type="uninstall" can be used to completely remove a
build time tool (e.g. a compiler) without having to specify a all
dependencies of that tool (as one would have when using
type="delete"). Consider the following example where we wish to compile a
custom program in
config.sh. We ship its source code via an
archive element and add the build tools (
<packages type="image"> and
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <!-- snip --> <packages type="image"> <package name="ca-certificates"/> <package name="coreutils"/> <package name="ninja"/> <package name="clang"/> <package name="meson"/> <archive name="foo_app_sources.tar.gz"/> </packages> <!-- These packages will be uninstalled after running config.sh --> <packages type="uninstall"> <package name="ninja"/> <package name="meson"/> <package name="clang"/> </packages> </image>
pushd /opt/src/foo_app mkdir build export CC=clang meson build cd build && ninja && ninja install popd
<packages type="uninstall"> element will make sure that the final
appliance will no longer contain our tools required to build
thus making our image smaller.
There are also other use cases for
type="uninstall", especially for
specialized appliances. For containers one can often remove the package
shadow (it is required to setup new user accounts) or any left over
partitioning tools (
fdisk). All networking tools can be
safely uninstalled in images for embedded devices without a network
KIWI supports the inclusion of openSUSE products or of namedCollections
(patterns in SUSE based distributions or groups for RedHat based
distributions). These can be added via the
child elements, which both take the mandatory
name attribute and the
namedCollection can be utilized to shorten the list of
packages that need to be added to the image description tremendously. A
named pattern, specified with the namedCollection element is a
representation of a predefined list of packages. Specifying a pattern will
install all packages listed in the named pattern. Support for patterns is
distribution specific and available in SLES, openSUSE, CentOS, RHEL and
Fedora. The optional
patternType attribute on the packages element allows
you to control the installation of dependent packages. You may assign one
of the following values to the
onlyRequired: Incorporates only patterns and packages that the specified patterns and packages require. This is a “hard dependency” only resolution.
plusRecommended: Incorporates patterns and packages that are required and recommended by the specified patterns and packages.
Packages can be explicitly marked to be ignored for installation inside a
packages collection. This useful to exclude certain packages from being
installed when using patterns with
patternType="plusRecommended" as shown
in the following example:
<image schemaversion="7.1" name="LimeJeOS-Leap-15.1"> <packages type="image" patternType="plusRecommended"> <namedCollection name="network-server"/> <package name="grub2"/> <package name="kernel"/> <ignore name="ejabberd"/> <ignore name="puppet-server"/> </packages> </image>
Packages can be marked as ignored during the installation by adding a
ignore child element with the mandatory
name attribute set to the
package’s name. Optionally one can also specify the architecture via the
arch similarly to The package element.
ignore elements as children of a
<packages type="delete"> or
<packages type="uninstall"> element has no effect! The packages will
still get deleted.