Contributor guide

The following outlines common directory locations:

  • Documentation - project documentation

  • releng_tool/api/ - api for supporting releng-tool extensions

  • releng_tool/engine/ - core implementation

  • releng_tool/ext/ - extensions that are maintained in the official tree

  • releng_tool/extract/ - translate fetched content to a build’s working area

  • releng_tool/fetch/ - support for fetching content from package sites

  • releng_tool/tool/ - definitions for host tools used by tool features

  • test/ - testing-related content for this project’s implementation

releng-tool is built on the Python language and aims to be the minimum dependency for users of the tool. Specific features enabled by a developer’s project may require additional tools (e.g. using Git to fetch sources requires git to be installed); however, a user should not be required to install tools for features that are not being used.


Developers are free to submit contributions for this project. Developers wishing to contribute should read this project’s CONTRIBUTING document. A reminder that any contributions must be signed off with the Developer Certificate of Origin.

Implementation (source, comments, commits, etc.) submitted to this project should be provided in English.

Root directory

A user invoking releng-tool will attempt to operate in a project root directory. Any content managed by this tool (e.g. creating directories, downloading sources, etc.) should all be performed inside the root directory. Some exceptions exist where a user requests to adjust the download directory (e.g. providing the --dl-dir argument).

Fetching design

Packages can describe where external content should be fetched from. The most common fetching method is a simple URI-style fetch such as downloading an archive from an HTTP/FTP location. Assets acquired in this manner are downloaded into the root directory’s download folder (e.g. <ROOT>/dl). The extraction phase will later use this folder to find package content to prepare against.

releng-tool also supports the fetching of content from version control systems. Sources can either be fetched and placed into an archive, in a similar fashion as fetching an archive from HTTP/FTP locations, or sources can be fetched into a “cache directory” if supported (typically distributed version controlled sources). For example, Git repositories (see also Git’s --git-dir) will be stored in the root directory’s cache folder (e.g. <ROOT>/cache). During the extraction stage, target revisions will be pulled from the cache location using the git client.

Not all packages will fetch content (e.g. placeholder packages).

Extraction design

In most cases, the extraction phase will process archives (e.g. .tar.gz, .zip, etc.) and place their content into a package’s build working directory. Implementation will vary for fetching implementation which stores content into a cache directory. For example, Git and Mercurial sources have their own extraction implementations to pull content from their respective distributed file systems into a package’s build working directory.

Host and Build environment

releng-tool attempts to minimize the impact of a host system’s environment on a project’s build. For example, the build phase of a package should not be pulling compiler flags provided from the host system’s environment. These flags should be provided from the package definition. Tools invoked by releng-tool will attempt to be invoked to ignore these external environment variables. Some exceptions apply such as environment variables dealing with authorization tokens.


Developers wishing to provide extensions to releng-tool should read the API implementation found in this tool’s repository (releng_tool/api/ Implementation in the API folder aims to be “API safe” – there is a strong attempt to prevent the changing of classes, methods, etc. to prevent compatibility issues as both releng-tool and extensions (if any) evolve. A developer for a releng-tool project would register an extension to load using the extensions configuration option inside the project configuration (releng):

#!/usr/bin/env python
# -*- coding: utf-8 -*-


extensions = [

On start, releng-tool will use this extension configuration to find and invoke the setup stage for each available extension.

An extension will define releng_setup to be registered into releng-tool. The call will provide an instance to the releng-tool application which allows an extension to register custom fetching, extraction and package implementations.

#!/usr/bin/env python
# -*- coding: utf-8 -*-

import releng_tool.api

def releng_setup(app):
    # explicit version check for releng-tool version (if needed)

    # fetch support (for custom fetch implementation)
    app.add_fetch_type('ext-myextension', <impl>)

    # extraction support (for custom extraction implementation)
    app.add_extract_type('ext-myextension', <impl>)

    # package support (configure, build, installation modifications)
    app.add_package_type('ext-myextension', <impl>)

For more information on available API interfaces, see the documentation found inside the API implementation.


Improvements to this project’s documentation (found inside Documentation) are always welcome – not only for adding/updating documentation for releng-tool features but also translations.

For users interested in translations for this project, please see the following repositories: