containers-images

Source files required used to build the Kubic containers.

Repository Layout

The source code of each image is organized as an independent KIWI project in a dedicated folder under the root of the repository.

Each folder contains a *kiwi.ini description file that is used as a template to generate the Kubic & CaaSP description files by running the pre_checking.sh script. This script will set the prefix for the image name and the base image to use.

Tagging images

The tag of the image is expected to be the same value as the main application that the image is providing. In order to keep the application version and image tag consistent over time there is an automation procedure in place for the builds within the Open Build Service. The replace_using_package_version service serves that purpose and should be used in the following way:

1. Include an arbitrary placeholder in the kiwi description file as the tag value.
2. In OBS set the replace_using_package_version service to replace the placeholder.

Consider the following example for a mariadb image:

1. In kubic-mariadb-image.kiwi use the %%VERSION%% placeholder:

(...)
<containerconfig name="kubic/mariadb" tag="%%VERSION%%"/>
(...)

2. In the _service file of the OBS project include:

<service name="replace_using_package_version" mode="buildtime">
    <param name="file">kubic-mariadb-image.kiwi</param>
    <param name="regex">%%VERSION%%</param>
    <param name="parse-version">minor</param>
    <param name="package">mariadb</param>
</service>

This configuration will set the tag to the mariadb package version at build time. This specially handy for images based on rolling releases like Tumbleweed, where the application versions might change at anytime.

The parse-version optional parameter is used to simplify the version string. It can take major, minor and patch values. patch will use a version style like MAJOR.MINOR.PATCH (three decimal numbers separated by dots), minor something like MAJOR.MINOR and major will just use the first decimal number. If not present the full version string is used.

Additional tags

Additional tags are appended in to the registry by using the following OBS specific syntax:

<!-- OBS-AddTag: name1:tag1 name2:tag2 -->

If tag includes the <RELEASE> marker this is replaced by the release number, which is different for every build. Thus using something like:

<!-- OBS-AddTag: kubic/mariadb:%%VERSION%%-<RELEASE> -->

Would produce an image reference like kubic/mariadb:10.2-5.1 where 10.2 stands for MAJOR.MINOR version of mariadb package and 5.1 stands for revision 5 build 1. This is an additional reference to what is defined within the kiwi description file.

The replace_using_package_version can be called multiple times in _service file, so tagging an image with multiple tags based on different version levels is also possible.

Consider the kiwi file has:

<!-- OBS-AddTag: kubic/mariadb:%%SHORT_VERSION%% kubic/mariadb:%%LONG_VERSION%%-<RELEASE> -->

and _service file has:

<service name="replace_using_package_version" mode="buildtime">
    <param name="file">kubic-mariadb-image.kiwi</param>
    <param name="regex">%%SHORT_VERSION%%</param>
    <param name="parse-version">major</param>
    <param name="package">mariadb</param>
</service>
<service name="replace_using_package_version" mode="buildtime">
    <param name="file">kubic-mariadb-image.kiwi</param>
    <param name="regex">%%LONG_VERSION%%</param>
    <param name="parse-version">patch</param>
    <param name="package">mariadb</param>
</service>

For this specific case the tags would be expanded to something like kubic/mariadb:10 and kubic/mariadb:10.2.3-6.2.

Note OBS-AddTag is only applied to published images when published to the registry, this has no effect on the resulting binary.