Build a Container Image¶
KIWI NG is capable of building native Container Images from scratch and derived ones. KIWI NG Container images are considered to be native since the KIWI NG tarball image is ready to be loaded into a Container Runtime like Podman, Docker or Containerd, including common container configurations.
The Container configuration metadata is provided to KIWI NG as part of the
XML description file using the
<containerconfig>
tag. The following configuration metadata can be
specified:
containerconfig
attributes:
name
: Specifies the repository name of the Container Image.tag
: Sets the tag of the Container Image.maintainer
: Specifies the author field of the container, this is equivalent to theMAINTAINER
directive in aDockerfile
.user
: Sets the user name or user id (UID) to be used when runningentrypoint
andsubcommand
. Equivalent of theUSER
directive of aDockerfile
.workingdir
: Sets the working directory to be used when runningcmd
andentrypoint
. Equivalent of theWORKDIR
directive in aDockerfile
.
containerconfig
child tags:
subcommand
: Provides the default execution parameters of the container. Equivalent of theCMD
directive in aDockerfile
.labels
: Adds custom metadata to an image using key-value pairs. Equivalent to one or moreLABEL
directives in aDockerfile
.expose
: Define which ports can be exposed to the outside when running this container image. Equivalent to one or moreEXPOSE
directives in aDockerfile
.environment
: Sets environment variables using key-value pairs. Equivalent to one or multipleENV
directives in aDockerfile
.entrypoint
: Sets the binary via which all commands inside the container will be executed. Equivalent of theENTRYPOINT
directive in aDockerfile
.volumes
: Create mountpoints with the given name and mark them to hold external volumes from the host or from other containers. Equivalent to one or moreVOLUME
directives in aDockerfile
.
Other Dockerfile
directives such as RUN
, COPY
or ADD
,
can be mapped to KIWI NG using the
config.sh script file to run bash commands
or the overlay tree to include
additional files.
The following example illustrates how to build a Container Image based on openSUSE Leap:
Make sure you have checked out the example image descriptions, see Example Appliance Descriptions.
Include the
Virtualization/containers
repository to your list:$ zypper addrepo http://download.opensuse.org/repositories/Virtualization:/containers/<DIST> container-tools
where the placeholder
<DIST>
is the preferred distribution.Install umoci and skopeo tools
$ zypper in umoci skopeo
Build the image with KIWI NG:
$ sudo kiwi-ng system build \ --description kiwi/build-tests/x86/leap/test-image-docker \ --set-repo obs://openSUSE:Leap:15.3/standard \ --target-dir /tmp/myimage
Test the Container image.
First load the new image into your Container Runtime:
$ podman load -i kiwi-test-image-docker.x86_64-1.15.3.docker.tar.xz
and then run the image:
$ podman run --rm -it buildsystem /bin/bash