poetry-multiproject-plugin 0.3.0

A Poetry plugin that aims to simplify package & dependency management for projects in Monorepos.

Poetry Multiproject Plugin

This is a Python Poetry plugin, adding commands with support for including packages outside of a project root.

This is achieved by setting the workspace (or commonly the repo) folder as the root folder. Also, the plugin makes it possible specify a project specific pyproject.toml file, useful when running commands from the workspace root.

Example usage: running the command from the workspace root folder

poetry build-project --t path/to/pyproject.toml

Optionally, run the command from the same folder as the actual project specific TOML file:

poetry build-project

Workspace?

A workspace is a place for code and projects. Within the workspace, code can be shared. A workspace is normally at the root of your repository. To enable your Python project as a workspace, just add an empty workspace.toml file at the top.

touch workspace.toml

The poetry-multiproject-plugin will look for the workspace.toml file to determine the workspace root.

Why workspaces?

Being able to specify package includes outside of a project root is especially useful when structuring code in a Monorepo, where projects can share components.

When the plugin is installed, there is a new command available: build-project.

How is it different from the "poetry build" command?

Poetry doesn't seem allow to reference code that is outside of the project root.

Something like this will cause the build to fail:

# this will fail using the default poetry build command

packages = [
    { include = "the_code_in_my_project"
    { include = "../../../my-shared-package" }]

By explicitly setting a workspace root, it is possible to reference outside components like this:

# this will work, when using the build-project command
packages = [
    { include = "the_code_in_my_project"
    { include = "../../../my-shared-package" }]

Simplified example of a monorepo structure:

projects/
  my-app/
    pyproject.toml (including a shared package)
    app.py

  my-service/
    pyproject.toml (including other shared packages)
    app.py

shared/
  my-package/
   __init__.py
   code.py

  my-other-package/
   __init__.py
   code.py

workspace.toml (a file that tells the plugin where to find the workspace root)

Using the preview of Poetry

This plugin depends on a preview of Poetry with functionality for adding custom Plugins. Have a look at the official Poetry preview docs for how to install it.

Install the plugin according to the official Poetry docs.

When installed, there will be a new command available: build-project.

Modifying the Poetry internals

Setting the workspace root is done by altering the internal properties of the Poetry objects. This is (naturally) a risk, an update of the Poetry tool could break the functionality of the plugin.

A long-term goal is to make a Pull Request to the Poetry repository, making this kind of functionality available in there. This plugin would no longer be necessary if the pull request is accepted and merged.

What's next? Any other commands?

Starting with the build-project command, and ready to add more custom commands if any of the existing ones are relevant to override when using a project specific TOML file.