Building in the Open Build Service

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Abstract

This document gives a brief overview how to build images with KIWI in version 9.19.6 inside of the Open Build Service. A tutorial on the Open Buildservice itself can be found here: https://en.opensuse.org/openSUSE:Build_Service_Tutorial

The next generation KIWI is fully integrated with the Open Build Service. In order to start it’s best to checkout one of the integration test image build projects from the base Testing project Virtualization:Appliances:Images:Testing_$ARCH:$DISTRO at:

https://build.opensuse.org

For example the test images for SUSE on x86 can be found here.

Advantages of using the Open Build Service (OBS)

The Open Build Service offers multiple advantages over running KIWI locally:

  • OBS will host the latest successful build for you without having to setup a server yourself.

  • As KIWI is fully integrated into OBS, OBS will automatically rebuild your images if one of the included packages or one of its dependencies or KIWI itself get updated.

  • The builds will no longer have to be executed on your own machine, but will run on OBS, thereby saving you resources. Nevertheless, if a build fails, you get a notification via email (if enabled in your user’s preferences).

Differences Between Building Locally and on OBS

Note, there is a number of differences when building images with KIWI using the Open Build Service. Your image that build locally just fine, might not build without modifications.

The notable differences to running KIWI locally include:

  • OBS will pick the KIWI package from the repositories configured in your project, which will most likely not be the same version that you are running locally. This is especially relevant when building images for older versions like SUSE Linux Enterprise. Therefore, include the custom appliances repository as described in the following section: Recommendations.

  • When KIWI runs on OBS, OBS will extract the list of packages from config.xml and use it to create a build root. In contrast to a local build (where your distributions package manager will resolve the dependencies and install the packages), OBS will not build your image if there are multiple packages that could be chosen to satisfy the dependencies of your packages 1. This shows errors like this:

    unresolvable: have choice for SOMEPACKAGE: SOMEPAKAGE_1 SOMEPACKAGE_2
    

    This can be solved by explicitly specifying one of the two packages in the project configuration via the following setting:

    Prefer: SOMEPACKAGE_1
    

    Place the above line into the project configuration, which can be accessed either via the web interface (click on the tab Project Config on your project’s main page) or via osc meta -e prjconf.

    Warning

    We strongly encourage you to remove your repositories from config.xml and move them to the repository configuration in your project’s settings. This usually prevents the issue of having the choice for multiple package version and results in a much smoother experience when using OBS.

  • By default, OBS builds only a single build type and the default profile. If your appliance uses multiple build types, put each build type into a profile, as OBS cannot handle multiple build types.

    There are two options to build multiple profiles on OBS:

    1. Use the <image> element and add it bellow the XML declaration (<?xml ..?>):

      <?xml version="1.0" encoding="utf-8"?>
      
      <!-- OBS-Profiles: foo_profile bar_profile -->
      
      <image schemaversion="7.1" name="openSUSE-Leap-15.1">
        <!-- image description with the profiles foo_profile and bar_profile
      </image>
      
    2. Use the multibuild feature.

    The first option is simpler to use, but has the disadvantage that your appliances are built sequentially. The multibuild feature allows to build each profile as a single package, thereby enabling parallel execution, but requires an additional _multibuild file. For the above example config.xml would have to be adapted as follows:

    <?xml version="1.0" encoding="utf-8"?>
    
    <!-- OBS-Profiles: @BUILD_FLAVOR@ -->
    
    <image schemaversion="7.1" name="openSUSE-Leap-15.1">
      <!-- image description with the profiles foo_profile and bar_profile
    </image>
    

    The file _multibuild would have the following contents:

    <multibuild>
      <flavor>foo_profile</flavor>
      <flavor>bar_profile</flavor>
    </multibuild>
    
  • Subfolders in OBS projects are ignored by default by osc and must be explicitly added via osc add $FOLDER 2. Bear that in mind when adding the overlay files inside the root/ directory to your project.

  • OBS ignores file permissions. Therefore config.sh and images.sh will always be executed through BASH (see also: User Defined Scripts).

Recommendations

Working with OBS

Although OBS is an online service, it is not necessary to test every change by uploading it. OBS will use the same process as osc build does, so if your image builds locally via osc build it should also build online on OBS.

Repository Configuration

When setting up the project, enable the images repository: the images repository’s checkbox can be found at the bottom of the selection screen that appears when clicking Add from a Distribution in the Repositories tab. Or specify it manually in the project configuration (it can be accessed via osc meta -e prj):

<repository name="images">
  <arch>x86_64</arch>
</repository>

Furthermore, OBS requires additional repositories from which it obtains your dependent packages. These repositories can be provided in two ways:

  1. Add the repositories to the project configuration on OBS and omit them from config.xml. Provide only the following repository inside the image description:

    <repository type="rpm-md">
      <source path="obsrepositories:/"/>
    </repository>
    

    This instructs OBS to inject the repositories from your project into your appliance.

    Additional repositories can be added by invoking osc meta -e prj and adding a line of the following form as a child of <repository name="images">:

    <path project="$OBS_PROJECT" repository="$REPOSITORY_NAME"/>
    

    The order in which you add repositories matters: if a package is present in multiple repositories, then it is taken from the first repository. The last repository is subject to path expansion: its repository paths are included as well.

    Don’t forget to add the repository from the Virtualization:Appliances:Builder project, providing the latest stable version of KIWI (which you are very likely using for your local builds).

    The following example repository configuration 3 adds the repositories from the Virtualization:Appliances:Builder project and those from the latest snapshot of openSUSE Tumbleweed:

    <project name="Virtualization:Appliances:Images:openSUSE-Tumbleweed">
      <title>JeOS for Tumbleweed </title>
      <description>Host JeOS images for Tumbleweed</description>
      <repository name="images">
        <path project="Virtualization:Appliances:Builder" repository="Factory"/>
        <path project="openSUSE:Factory" repository="snapshot"/>
        <arch>x86_64</arch>
      </repository>
    </project>
    

    The above can be simplified further using the path expansion of the last repository to:

    <project name="Virtualization:Appliances:Images:openSUSE-Tumbleweed">
      <title>JeOS for Tumbleweed </title>
      <description>Host JeOS images for Tumbleweed</description>
      <repository name="images">
        <path project="Virtualization:Appliances:Builder" repository="Factory"/>
        <arch>x86_64</arch>
      </repository>
    </project>
    

    Now Virtualization:Appliances:Builder is the last repository, which’ repositories are included into the search path. As openSUSE:Factory/snapshot is among these, it can be omitted from the repository list.

  2. Keep the repositories in your config.xml configuration file. If you have installed the latest stable KIWI as described in Installation then you should add the following repository to your projects configuration (accessible via osc meta -e prjconf), so that OBS will pick the latest stable KIWI version too:

    <repository name="images">
      <path project="Virtualization:Appliances:Builder" repository="$DISTRO"/>
      <arch>x86_64</arch>
    </repository>
    

    Replace $DISTRO with the appropriate name for the distribution that you are currently building and optionally adjust the architecture.

We recommend to use the first method, as it integrates better into OBS. Note that your image description will then no longer build outside of OBS though. If building locally is required, use the second method.

Warning

Adding the repositories to project’s configuration makes it impossible to build images for different distributions from the same project.

Since the repositories are added for every package in your project, all your image builds will share the same repositories, thereby resulting in conflicts for different distributions.

We recommend to create a separate project for each distribution. If that is impossible, you can keep all your repositories (including Virtualization:Appliances:Builder) in config.xml. That however usually requires a large number of workarounds via Prefer: settings in the project configuration and is thus not recommended.

Project Configuration

The Open Build Service will by default create the same output file as KIWI when run locally, but with a custom filename ending (that is unfortunately unpredictable). This has the consequence that the download URL of your image will change with every rebuild (and thus break automated scripts). OBS can create symbolic links with static names to the latest build by adding the following line to the project configuration:

Repotype: staticlinks

If build Vagrant images (see KIWI Image Description for Vagrant) add the repository-type vagrant. OBS creates a boxes/ subdirectory in your download repositories, which contains JSON files for Vagrant 4.

If you have added your repositories to config.xml, you probably see errors of the following type:

unresolvable: have choice for SOMEPACKAGE: SOMEPAKAGE_1 SOMEPACKAGE_2

Instead of starting from scratch and manually adding Prefer: statements to the project configuration, we recommend to copy the current project configuration of the testing project Virtualization:Appliances:Images:Testing_$ARCH:$DISTRO into your own project. It provides a good starting point and can be adapted to your OBS project.

1

This is a design decision made by OBS: as it’s purpose is to build packages in a reproducible fashion it cannot make a decision which package to choose from multiple available ones. A package manager build for end-users on the other hand must make an a choice, as it would be otherwise hardly usable.

2

osc compresses added folders into a cpio archive and decompresses it before running your builds. The only downside of this is, that the contents of your overlay is not conveniently visible via the web interface.

3

Taken from the project Virtualization:Appliances:Images:openSUSE-Tumbleweed

4

Vagrant uses these JSON files for automatic updates of your Vagrant boxes.