The kraken-common package is the shared utility namespace for the Kraken build system and the Kraken wrapper CLI. It contains various generic utilities, as well as the tools for loading the metadata of a Kraken project.

Aside from general utilities that are used by one, the other or both, this package also implements the shared logic for executing Kraken Python and BuildDSL build scripts and retrieving its metadata.

The following types of Kraken script runners are currently available via the kraken.common package:

• PythonScriptRunner: Matches a kraken.py or .kraken.py file and runs it as a pure Python script.
• BuildDslScriptRunner: Matches a kraken.build or .kraken.build file and runs it as a builddsl script, with the buildscript() function being available by default.

A Kraken project contains at least one .kraken.py file (build script) and maybe a .kraken.lock file (lock file). The build script at the root of a project may contain hints for the Kraken wrapper CLI to be able to correctly bootstrap an environment that contains the Kraken build system.

from kraken.common import buildscript

buildscript(
    requirements=["kraken-std ^0.4.16"],
)

buildscript {
    requires "kraken-std ^0.4.16"
}

The way that this works is that the buildscript() function raises an exception that aborts the execution of the build script before the rest of the script is executed, and the exception contains the metadata. When the build script is executed by the Kraken build system instead, the function does nothing.

The API to capture the data passed to a call to the buildscript() function is as follows:

from kraken.common import BuildscriptMetadata

with BuildscriptMetadata.capture() as metadata_future:
    ...

metadata = metadata_future.result()