petal-ros 0.1.1

Workspace-scoped Python dependency manager for ROS2

petal

Workspace-scoped Python dependency manager for ROS2.

Petal discovers Python dependencies in a ROS2 workspace, resolves apt-first, falls back to PyPI when needed, installs pip packages into .petal/venv, and writes petal.lock.

Petal is dependency management, not node isolation. ROS2 still runs in one shared Python interpreter view, so petal venvs are created with --system-site-packages.

Install

uv tool install petal-ros

If you use the colcon verb, install the colcon extra:

uv tool install "petal-ros[colcon]"

Local development:

git clone https://github.com/matthewyjiang/petal.git
cd petal
python3 -m pip install -e .

Requires Python 3.10+, ROS2 under /opt/ros/<distro>, rosdep, apt tools, and preferably uv.

Quickstart

From a ROS2 workspace root:

petal init
petal add numpy
petal sync
petal status
source .petal/activate

Examples

Apt-resolved package:

petal add numpy

PyPI package:

petal add huggingface

Rosdep-resolved ROS package:

petal add cv_bridge

Commands

petal init              # create petal.toml and .petal/venv
petal add <name> [spec] # add dependency and sync it
petal remove <name>     # remove dependency from manifest and venv
petal sync              # resolve, install, write petal.lock
petal sync --yes        # skip install prompt
petal sync --no         # show plan, install nothing
petal sync --dry-run    # show commands, install nothing
petal sync --frozen     # enforce petal.lock
petal status            # report drift; exits 2 on drift/missing/change
petal activate          # print shell snippet for ROS + venv activation
petal clean             # remove .petal/venv

petal sync and petal add print the resolved source for each dependency before installing. If petal add is declined, cancelled, or run with --dry-run, petal.toml stays unchanged.

Manifest

[workspace]
ros_distro = "humble"
python_version = "3.10"

[deps]
numpy = ">=1.24"
huggingface = ">=0.0.1"
some-system-lib = { apt = "libfoo-dev" }

[overrides]
ml_collections = { pip = "ml-collections" }

Resolution order: ROS/system modules, rosdep, apt (python3-<name>), then PyPI.

Colcon Verb

Petal ships a colcon deps verb. Install with the colcon extra:

uv tool install "petal-ros[colcon]"

Then from a ROS2 workspace root:

colcon deps sync              # resolve and install dependencies
colcon deps status            # report drift; exits 2 on drift/missing/change
colcon deps sync --dry-run    # show plan, install nothing
colcon deps sync --frozen     # enforce petal.lock
colcon deps sync --workspace /path/to/ws  # explicit workspace path

colcon deps is a thin wrapper around petal sync / petal status and honours the same flags.

Development

uv run --with pytest pytest -q

Unit tests use fake subprocess runners and do not require network, real ROS, apt, rosdep, uv, or colcon.