WARNING: work in progress

Use this repository at your own risk. This is a work in progress. For official ROS2 yocto layers, refer to this repository

meta-ros2 generator

This repository contains a script to generate bitbake recipes for ROS2. It does so by using a package list from here

Next, the script will download the zipfile, extract the meta-data and generate bitbake recipes.

Usage

 $ mkdir git
 $ git clone https://github.com/ros/rosdistro.git
 $ git clone https://github.com/windelbouwman/meta-ros2-generator.git
 $ cd meta-ros2-generator
 $ python make_meta_ros.py ../rosdistro/dashing/distribution.yaml meta-ros2/recipes-generated

Now, to use this, include the meta-ros2 layer in your build, and build rclpy for example:

 $ bitbake rclpy

Directories

• meta-ros2 : ros2 meta layer for yocto
• meta-ros2/recipes-generated : folder filled with data from the script in this repo.
• meta-ros2/recipes-manual/dependency-patches : a folder with patches to yocto recipes to satisfy ros2 dependencies on non-ros2 packages
• meta-ros2/recipes-manual/python-packages : some python packages which are pretty new.
• meta-ros2/recipes-manual/ros2-patches : specific ros2 recipe patches. This folder would ideally be empty.

Design

To build ROS2 upon yocto/openembedded, we take the distribution file of ROS2, which is a YAML file with a list of target packages and versions. This distribution file describes a certain ROS2 distribution. Each package and version points to an URL where the ROS package is located. This package is then downloaded, and its meta data is inspected.

The meta data of each ROS2 package contains information about the build-tool, and the dependencies of the package.

The build-tool is most of the cases ament-cmake, cmake or ament-python. ROS uses a custom build system on top of cmake, called ament. For this build type, we create a bbclass for the openembedded build system.

For each ROS package, we create a bitbake recipe automatically. Not all generated recipes work out of the box as expected, so for these cases, we create some extra additions to the recipe in the form of a .bbappend file. These bbappend files modify the automatically generated recipes so that they are compilable.

Notable issues:

• poco-vendor and yaml-vendor. These libraries are a wrapper around the poco and yaml libraries. The strategy for these libraries is to prevent their usage, and modify the recipes which include them, to not include those libraries, but the original yaml and poco libraries instead.

• ament-cmake: this package requires itself as build system. This means that ament-cmake is build using ament-cmake. This results in a circular dependency. To solve this, we build ament-cmake with cmake. This works.