Root Generator

The root generator is responsible for generating and conifguring a tarball of the root filesystem. The root generator supports the following parameters:

config_file: Path to the yaml configuration file of the root filesystem.
output: Path to the folder where the generated artifacts are placed.
–no-config: Skip the configuration step. This flag allows a two-step build which first creates the tarball containing all selected packages, and then applies the use configuration.
–sysroot: The sysroot flag allows to add additional packages only required as part of the sysroot for cross-compiling.

The core part of the root generator is implemented in ebcl/tools/root/root.py. The main function takes care of parsing the command line parameters and then runs create_root of the RootGenerator class, and finally runs finalize to cleanup temporary artifacts.

The build process implemented in create_root executes the following high level steps:

In case of a sysroot build: Add additional packages to the list of selected packages.
Create the root tarball using either elbe, kiwi or debootstrap.
In case of not skipping the configuration: Copy the overlays and run the config scripts.
Move the resulting tarball to the output folder.

Implementation details

Root tarball generation

TODO: write section

Root configuration

The root filesystem configuration is shared code between the root generator and the root configurator and is implemented in ebcl/tools/root/init.py. For configuring the root tarball the following steps are executed:

Extract the tarball to a temporary folder.
Copy the host files to this folder, overwriting existing files if necessary.
Execute the configuration scripts in the given environment.
Pack the result as tarball.

Copying of the files and running the scripts is common code for all tools and implemented in the Files class contained in ebcl/common/files.py.

Copy the host files

The host files which shall be overlayed to the root filesystem are defined in the configuration file using the host_files parameters. These configuration is parsed using parse_files of ebcl/common/files.py. For each file or folder a source value is required. This source value is interpreted as relative path to the config file. Optionally a destination, a mode, a uid and a gid can be given. These additional parameters are evaluted by copy_files. If uid and gid is not given, the user id 0, and the group id 0 is used, which means root user and group. If no mode is given the mode is not modified, i.e. the value is kept for the file.

Run the configuration scripts