What is this?
This is a resource made, admittedly mostly for myself, that will allow me to recall a method of Python dev environment management I don't dislike. It covers the use of two distinct but important Python environment helpers:
- PyEnv (Docs)
- Uses path shims to help you manage several versions of Python simultaneously.
- Poetry (Docs)
- A dependency manager that feels similar in my approximation to a tool like
yarnornpmfrom the Node world, and automates certain tasks (venv creation and activation for example).
- A dependency manager that feels similar in my approximation to a tool like
Why make this / why read this?
- You find that managing Python projects in a clean, repeatable, and predictable way is less simple (or less fun) than you have found the process to be in other languages.
How do I use / read this?
This is a technical guide not an in depth explanation (though that may be forthcoming) and so I expect this guide to be used primarily as a way to kick start your memory on how to set up Python projects in a way you don't dislike. Best of luck 🍀
Pre-Reqs 🫸
These steps are to be done once per machine and if you've already accomplished these steps you may skip this section.
Install PyEnv & A Modern Python Version 🐍
brew update
brew install pyenv
pyenv --version
# pyenv 2.3.15
pyenv install 3.10.7
# Wait for a bit for install to finish...
pyenv shell 3.10.7
python --version
# Python 3.10.7 🎉
Optional: Set A System Wide Python Version
pyenv global 3.10.7
Install Poetry ✍️
curl -sSL https://install.python-poetry.org | python3 -
poetry --version
Optional: Tell poetry to create virtual environments in the current project directory
poetry config virtualenvs.in-project true
poetry config virtualenvs.in-project
# true
Steps 🧭
- Make a new project directory
cd Desktop/Code/personal/python
mkdir planet-express-api
cd planet-express-api
- Set a Python version for this project directory
pyenv local 3.10.7
python --version
# 3.10.7
cat .python-version
# 3.10.7
Note: This command will create a file that pyenv looks for in the current working directory (the folder you are in) whose content will tell pyenv which Python version to use.
- Create a poetry project
# Leave off the -n flag if you wish to add precise data
# to the pyproject.toml file poetry creates.
poetry init -n
ls | grep pyproject.toml
# pyproject.toml
- Initialize and start your Virtual Environment using poetry
poetry shell
# Creating virtualenv planet-express-api
# bash -c planet-express-api/.venv/bin/activate
- Test it by adding a dependency
# Add a dependency
poetry add pendulum
# Start a Python REPL
python
# Use the dependency
import pendulum
now = pendulum.now("Europe/Paris")
now.to_iso8601_string()
# '2023-05-27T19:40:17.452958+02:00'
# Use `ctrl + d` to exit the REPL
- Stop using the virtual environment
# Exit the virtual environment
deactivate
# Start a Python REPL
python
# Validate the dependency is not available
import pendulum
ModuleNotFoundError: No module named 'pendulum'
Note: To get back into the virtual environment just use poetry shell again.
Summary
In this article you have used PyEnv and Poetry together to create a project in a desired version of Python (pyenv) whose dependencies and virtual environment are managed by a single robust tool (poetry) cheers to you 🍻
Top comments (2)
When you do this do you ever get a problem with Poetry's shell not respecting the pyenv version? I tested, and the first directory I created the .python-version file in (using pyenv local 3.7.17) was fine, but then I
poetry initandpoetry shelland it gives me python 3.10.6, my system version.I wound up using the solution from the very last post of this github issue. Upon setting that poetry config item, it then respected the version.
If it matters, I installed Poetry using pipx.
Couple of things:
python-poetry.org/docs/#installation
github.com/python-poetry/poetry/is...