una 0.4.0

Python monorepo tooling

Una

Easy monorepos with Python

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Una is a tool to make Python monorepos easier. It is a CLI tool and a build plugin that does the following things:

1. Enable builds of individual apps or projects within a monorepo.
2. Ensure that internal and external dependencies are correctly specified.

Una doesn't try to replicate a full build system such as Bazel or Pants. It just makes it possible to have a simple monorepo with interdependencies.

Una works much like a Rust workspace, with each package having its own pyproject.toml. In general, packages should either be libraries (imported but not run) or apps (run but never imported), but Una will not enforce this.

Currently it works with the following build backends, but more will follow:

• Hatch (used by default and and in all documentation)
• PDM

All instructions and examples use uv for local development.

Examples

You can see an example repo here:

• una-example

Quickstart

This will give you a quick view of how this all works.

First install uv:

curl -LsSf https://astral.sh/uv/install.sh | sh

And start your workspace:

uv init unarepo   # choose another name if you prefer
cd unarepo
git init
uv add --dev una

Then setup the Una workspace. This will generate a structure and an example lib and app.

uv run una create workspace
rm -rf src
uv sync

Have a look at what's been generated:

tree

Have a look at the generated __init__.py files in the apps/printer and libs/greeter packages. An external dependency (cowsay-python) has also been added to the latter's pyproject.toml.

The magic of Una then comes in to resolve the graph of direct and transitive dependencies, which looks like this:

printer --> greeter --> cowsay-python

You can do this by running the following:

# this checks all imports and ensures they are added to
# [tool.una.deps] in the appropriate pyproject.toml
uv run una sync

Have a look at what happened:

tail apps/printer/pyproject.toml

It added greeter as an internal dependency to printer. It didn't add cowsay-python, as external dependencies are only resolved at build-time (keep reading).

Now you can build your app:

uvx --from build pyproject-build --installer=uv --outdir=dist apps/printer
# this will inject the cowsay-python externel dependency

And see the result:

ls dist/

And you can do whatever you want with that wheel! What about stick it in a Dockerfile, have you ever seen such a simple one?

FROM python
COPY dist dist
RUN pip install dist/*.whl

And run it:

docker build --tag unarepo-printer .
docker run --rm -it unarepo-printer python -c 'from unarepo.printer import run; run()'

Installation

The CLI tool isn't strictly necessary, as all the stuff that lets the monorepo builds work is in the separate (and tiny) hatch-una package. But you will likely struggle to manage your monorepo without the tool!

So you may as well install it:

uv add --dev una

As for the build-time hatch-una, it will automatically be installed by build tools when it spots this in your pyproject.toml (this will be configured automatically by the CLI):

[build-system]
requires = ["hatchling", "hatch-una"]
build-backend = "hatchling.build"

Usage

The CLI has a few commands and options, have a look:

uv run una --help

 Usage: una [OPTIONS] COMMAND [ARGS]...

╭─ Options ─────────────────────────────────────────────╮
│ --help          Show this message and exit.           │
╰───────────────────────────────────────────────────────╯
╭─ Commands ────────────────────────────────────────────╮
│ create   Commands for creating workspace and packages.│
│ sync     Update packages with missing dependencies.   │
╰───────────────────────────────────────────────────────╯

Documentation

Read more at the official documentation.

It covers additional things like:

• type-checking, testing, editor integration
• and more!

Contributing

See the instructions at the official documentation.

Very briefly, local development is with uv:

uv sync
make all  # will fmt, lint, typecheck and test

Then open a PR.

License

Una is distributed under the terms of the MIT license. Some code is from the python-polylith project (c) 2022 David Vujic