Python Monorepos & the Polylith Developer Experience [video]

David Vujic — Sun, 18 May 2025 09:33:11 +0000

What if writing software would be more like when building things with LEGO bricks? For me, a more playful and productive Developer Experience is all about writing & experimenting with code - without the hassle.

A productive setup should also let us make design decisions while learning what to actually build, and allow changes during the way.

The Polylith Architecture solves this in a Nice and Simple way. I am the developer of the Open Source tooling for Polylith in Python.

In this video from FOSDEM 2025, I go through the basics of the Polylith Architecture & the Developer friendly tooling for a joyful and hassle-free Python Experience.

References
The Python tools for the Polylith Architecture docs
The Python tools for the Polylith Architecture at GitHub

Introducing a new command to the Python Polylith tool

David Vujic — Sat, 17 May 2025 07:41:10 +0000

The Python tools for the Polylith Architecture now has a new command called poly test. As of this release, the command is used with a sub-command: poly test diff.

But wait, what's Polylith?

The main use case is to support having one or more Microservices (or apps) in a Monorepo, and share code between the services.

Polylith is an architecture, with tooling support. Polylith is using a components-first architecture. You can think of it as building blocks, very much like LEGO bricks. All code lives in a Monorepo, available for reuse. Python code, the set of LEGO bricks, is separated from the infrastructure and the actual building of your deployable artifacts. Have a look at the docs for more details, or the #polylith tag here in this community.

The poly test command
This new command is adding the possibility to identify bricks and projects that are affected by changes in tests. In its structure, the new command is very much like the existing poly diff command (that will display changed bricks compared to a git tag).

The poly test diff command will show you any affected bricks or projects when the automated tests have been updated. When changing a test that imports a brick, the command will report the brick as affected. The command can also report on the affected project(s), based on the affected brick.

Example usage:

# Poetry
poetry poly test diff

# CLI users, such as uv
uv run poly test diff

Affected bricks:

# Poetry
poetry poly test diff --bricks

# CLI users, such as uv
uv run poly test diff --bricks

Affected projects:

# Poetry
poetry poly test diff --projects

# CLI users, such as uv
uv run poly test diff --projects

References
The Python tools for the Polylith Architecture documentation
The Python tools for the Polylith Architecture at GitHub

DEV Community: David Vujic

Python Monorepos & the Polylith Developer Experience [video]

Introducing a new command to the Python Polylith tool