ROS2 for Rust

Build status

Target	Status
Ubuntu 20.04

Introduction

This is a set of projects (bindings, code generator, examples and more) that enables developers to write ROS2 applications in Rust.

Features

The current set of features include:

Generation of all builtin ROS types
Support for publishers and subscriptions
Tunable QoS settings

What's missing?

Lots of things!

Component nodes
Clients and services
Tests
Documentation

Limitations

The rclrs interface is very limited for now and might not be idiomatic yet, any help and suggestion on the interface would be greatly appreciated
Due to the current ROS2 support of non-default clients, packages containing definitions of messages used in Rust crates must be present in the current workspace; otherwise message crates generation won't be triggered

Sounds great, how can I try this out?

Here, the Foxy distribution of ROS 2 is used, but newer distributions can be used by simply replacing 'foxy' with the distribution name.

# First, make sure to have ROS 2 and vcstool installed (alternatively, install vcstool with pip):
# sudo apt install ros-foxy-desktop ros-foxy-test-interface-files python3-vcstool libclang-dev clang
# Install the colcon-cargo and colcon-ros-cargo plugins
pip install git+https://github.com/colcon/colcon-cargo.git git+https://github.com/colcon/colcon-ros-cargo.git
# Install the cargo-ament-build plugin
cargo install cargo-ament-build

# In your workspace directory (ideally an empty one), run 
mkdir src
git clone https://github.com/ros2-rust/ros2_rust.git src/ros2_rust
vcs import src < src/ros2_rust/ros2_rust_foxy.repos
. /opt/ros/foxy/setup.sh
cd /src
colcon build --packages-up-to rclrs_examples

It's normal to see a Some selected packages are already built in one or more underlay workspace warning. This is because the standard message definitions that are part of ROS 2 need to be regenerated in order to create Rust bindings.

If something goes very wrong and you want to start fresh, make sure to delete all install*, build* and .cargo directories. Also, make sure your terminal does not have any install sourced (check with echo $AMENT_PREFIX_PATH, which should be empty).

Building with `cargo`

As an alternative to colcon, Rust packages can be built with pure cargo.

However, this will not work out of the box, since the Cargo.toml files contain dependencies like rclrs = "*", even though rclrs is not published on crates.io. This is intentional and follows ROS 2's principle for packages to reference their dependencies only with their name, and not with their path. At build-time, these dependencies are resolved to a path to the local package by colcon, and written into .cargo/config.toml. Therefore, the package in question should be built with colcon once, and after that cargo will be able to use the .cargo/config.toml file to find all dependencies.

A second catch is that cargo message packages link against native libraries. A convenient way to ensure that they are found is to also source the setup script produced by colcon.

As an example, here is how to build rclcrs_examples with cargo:

# Initial build of the package with colcon
# Compare .cargo/config.toml with and without the --lookup-in-workspace flag to see its effect
colcon build --packages-up-to rclrs_examples --lookup-in-workspace
# Source the install directory
. install/setup.sh
cd rclrs_examples
# Run cargo build, or cargo check, cargo doc, etc.
cargo build

Running the publisher and subscriber

Publisher:

# Do this in a new terminal
. ./install/setup.sh
ros2 run rclrs_examples minimal_publisher

Subscriber:

# Do this in a new terminal
. ./install/setup.sh
ros2 run rclrs_examples minimal_subscriber

Enjoy!

jpace121/ros2_rust