Convert Python requirements to Poetry format

I recently wrote about migrating a Python project to Poetry, however, this guide is quite manual process. I recently came across dephell, which seems to be able to automate some part of it. I wanted to check out how it might help for this follow-up post.

Migrate setup.py stuff

First step is to migrate meta-data and direct dependencies specified in setup.py file:

dephell deps convert \
  --from=setup.py \
  --to-format=poetry \
  --to-path=pyproject.toml

This converts some package metadata and add the dependencies which are listed in your setup.py.

Convert development dependencies

The development dependencies are located in requirements.in (as I used pip-tools), and to not overwrite the dependencies from the previous step, let’s write them to a temporary file:

dephell deps convert \
  --from=requirements.in \
  --to-format=poetry \
  --to-path=pyproject-dev.toml

Create a new section for development dependencies in pyproject.toml and move over dependencies from pyproject-dev.toml:

[tool.poetry.dev-dependencies]
# copy deps from pyproject-dev.toml here

Now you can get rid of the temporary pyproject-dev.toml file.

Finish

As far as I’m aware, that is as far as this tool will get you. The pyproject.toml file should almost be ready for Poetry, you can try running poetry install and fix the remaining issues.

In my case, here are the things I needed to adjust:

• the minimum Python version wasn’t properly detected, it was just '*' despite my setup.cfg having python_requires >= 3.6.
• Not all metadata were converted, I had to finish them manually.
• Some extra classifiers were included although Poetry can generate some of them automatically.
• Other tools configured via setup.cfg which I wanted to migrate to pyproject.toml are not migrated by this tool, it’s -understandably- out of its scope.

Nevertheless, this tool could speed up migration for projects with lots of dependencies.