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Package resolution design

The package resolution design can be separated in three logical parts:

  1. Running the EIB container - how to run the EIB container so that the RPM resolution has the needed permissions
  2. Building the EIB image - what happens during the RPM resolution logic of EIB's image build
  3. Booting the EIB image - how are the packages actually installed once the EIB image is booted for the first time

Running the EIB container

image

The package resolution workflow begins with the user specifying packages and/or stand-alone RPMs that will be installed when the EIB image is booted. On how to to do a correct specification, see Specify packages for installation.

After the desired specification has been made, the user runs the EIB container with the --privileged option, ensuring that EIB has the needed permissions to successfully run a Podman instance within its container. This is a crucial prerequisite for building a working EIB image with package installation specified (more on this in the next section).

An example of the command can be seen below:

podman run --rm --privileged -it \
-v $IMAGE_DIR:/eib eib:dev build \
--definition-file $DEFINITION_FILE.yaml

NOTE: Depending on the cgroupVersion that Podman operates with, you might also need to run the command with root permissions. This is the case for cgroupVersion: v1. In this version, non-root usage of the --privileged option is not supported. For cgroupVersion: v2, non-root usage is supported.

In order to check the cgroupVersion that Podman operates with, run the following command:

podman info | grep cgroupVersion

Once the EIB container has been successfully executed, it parses all the user provided specification and begins the RPM resolution process.

Building the EIB image

During this phase, EIB prepares the user specified packages for installation. This process is called RPM resolution and it includes:

  1. Validating that each provided package has a GPG signature or comes from a GPG signed RPM repository
  2. Resolving and downloading the dependencies for each specified package
  3. Creating a RPM repository that consists of the specified packages and their dependencies
  4. Configuring the usage of this repositry for package installation during the combustion phase of the EIB image boot

RPM resolution process

image

EIB mainly utilizes Podman's functionality to setup the environment needed for the RPM resolution process. In order to communicate with Podman, EIB first creates a listening service that will facilitate the communication between its own container and Podman. From here onwards, assume that any Podman related operation that EIB does goes through the listening service first.

Once EIB establishes communication with Podman, it parses the user configured ISO/RAW file and converts it to a Podman importable virtual disk tarball. This tarball is imported as an image in Podman.

EIB then proceeds to build the RPM resolver image using the tarball image as a base. This procedure ensures that the validation/resolution of any packages that are specified for installation will be as close to the desired user environment as possible.

All the RPM resolution logic is done during the build of the RPM resolver image. This includes, but is not limited to:

  1. Environment setup:
    • Connecting to SUSE's internal RPM repositories, if specified by the user through operatingSystem.packages.sccRegistrationCode
    • Importing any GPG keys provided by the user under <eib-config-dir>/rpms/gpg-keys
    • Adding any third-party RPM repositories, if specified by the user through operatingSystem.packages.additionalRepos
  2. Validation of:
    • RPM files provided by the user under <eib-config-dir>/rpms
    • Third-party RPM repositories, if specified by the user through operatingSystem.packages.additionalRepos
  3. Downloading the dependencies for all specified packages and side-loaded RPMs to a RPM cache directory

After a successful RPM resolver image build, EIB starts a container from the newly built image and copies the aforementioned RPM cache directory to the combustion directory located in the EIB container. This cache directory is then converted to a ready to use RPM repository by EIB.

The final step in the EIB RPM resolution process is to create an install script which uses the aforementioned RPM repository to install the user specified packages during the EIB image combustion phase.

Troubleshooting

When troubleshooting the RPM resolution process, it is beneficial to look at the following files/directories inside of the EIB build directory:

  1. eib-build.log - general logs for the whole EIB image build process
  2. podman-image-build.log - logs for the build of the EIB resolver image. If missing, but the resolver-image-build directory is present, this means that there is a problem in the configuration of the resolver-image-build directory
  3. podman-system-service.log - logs for the Podman listening service
  4. resolver-image-build directory - build context for the resolver image. Make sure that the Dockerfile holds correct data. When installing side-loaded RPMs, make sure that the rpms and gpg-keys directories are present in the resolver-image-build directory
  5. resolver-tarball-image directory - contains resources related to the creation of the virtual disk tarball archive. If this directory exists, this means that a problem has been encountered while EIB was trying to import the tarball image
  6. prepare-resolver-base-tarball-image.log - logs related to the creation of the virtual disk tarball
  7. createrepo.log - logs related to the conversion of the RPM cache directory to a RPM repository
  8. combustion/rpm-repo directory - the RPM repository; should hold the desired RPMs for installation and their dependencies
  9. combustion/10-rpm-install.sh - script that will be executed during the combustion phase; should use the rpm-repo repository and have all the expected packages specified for installation

Booting the EIB image

During the combustion phase of the EIB image boot, as mentioned above, both the RPM repository and RPM combustion script will be present in the combustion configuration directory respectively under /dev/shm/combustion/config/10-rpm-install.sh and /dev/shm/combustion/config/rpm-repo.

The root combustion script then calls the 10-rpm-install.sh script, which does the following:

  1. Adds the rpm-repo directory as a local RPM repository for its package manager
  2. Installs the desired packages from the newly added rpm-repo repository
  3. Once all packages have been installed it removes the rpm-repo from the package manager

The successful execution of the 10-rpm-install.sh script indicates that all packages have been installed on the operating system. Upon the completion of the image boot, the user should have access to every package that he specified when building the EIB image.