Managing Virtual environments in Python Poetry
Poetry helps you declare, manage, and install dependencies of Python projects, ensuring you have the right stack everywhere. Poetry is a tool for dependency management and packaging in the PHP programming language that helps in managing project dependencies and creating virtual environments. Unlike other tools like pip and virtualenv, Poetry is a single tool that offers dependency management, packaging, and virtual environment creation. Poetry replaces setup.py, requirements.txt, setup.cfg, MANIFEST.in and Pipfile with a simple pyproject.toml based project format. This guide will guide you on how to create and control virtual environment using Poetry in order to achieve a very clean environment for developers.
Setting Up Virtual Environments
Poetry provides such tools also, which automatically define as well as maintain virtual environments for your respective projects. Here’s how you can get started:
Install Poetry
use the following command on the terminal to install poetry:
pip install poetry
Initialize a New Project
Create a new project directory and initialize it with Poetry.
mkdir my_project
cd my_project
Run poetry init
Use the poetry init command to start the interactive setup for your pyproject.toml file:
poetry init
Follow the Prompts
This shall give you fields that require some input about your project. Below is an example :
project setup prompts
Managing Environment Isolation
Another important feature offered by Poetry is controlling of environment isolation concerning dependent packages for different projects. Here’s how Poetry handles this:
1. Creating a Virtual Environment
When you use Poetry Install or Poetry Add, Poetry first determines the exact location of the cache directory and then create a virtual environment inside it.
2. Checking the Virtual Environment
You can check the path of the virtual environment using the following command:
poetry env info --path
3. Activating the Virtual Environment
Activate the virtual environment to run commands within it and you will see your virtual env created will get activated.
poetry shell
a package named Numpy activated
To deactivate, simply exit the shell session.
4. Customizing Virtual Environment Location
You can configure Poetry to create virtual environments in specific directories by setting the virtualenvs.in-project setting to true.
poetry config virtualenvs.in-project true
This will establish the virtual environment within your project’s root folder so that you can easily find it and control it.
Working with Virtual Environments
Once your virtual environment is set up, you can perform various tasks to manage your dependencies and project environment.
Adding Dependencies
Other related packages can be included in your project and will be installed in the virtual environment created by poetry. Let’s say, you want to install Django:
poetry add django
Removing Dependencies
In case the existing dependencies are no longer required, get rid of them in your project, using the following command:
poetry remove <package-name>
Listing Dependencies
Display a list of dependencies and libraries that are installed with the application and their associated version numbers, using the following command:
poetry show
List of all installed dependencies
Running Scripts
Run programs and perform operations in the scope of a virtual environment.
poetry run python script.py
Updating Dependencies
Add compatibility to your project dependencies with their newer versions if available.
poetry update
Conclusion
With Poetry, managing dependencies and organizing project-specific virtual environments are streamlined as the tool is designed to handle these aspects within Python. Adherence to the steps drawn here will make your Python projects cleanly separated and easy to organize and manage.
FAQs
Can I manually edit the pyproject.toml file?
Yes, of course, you can edit it using a text editor and change the pyproject.toml file to change such project settings and other options of the project or its dependencies needed for the build. However, if possible, it is good to use Poetry’s CLI commands due to consistency and guarantee of correctness.
How do I install dependencies listed in the pyproject.toml file?
Specify a list of dependencies in the project file named ‘pyproject.toml’ to apply the ‘poetry install’ command. Poetry will make a new environment for this role and download all necessary packages into it.
How can I specify exact versions for dependencies in pyproject.toml?
It is also possible to specify specific versions for depended projects by putting a version constraint with no range. For example, flask = “2.0.1” specifies that version 2.0.1 of Flask should be used.
How can I ensure my virtual environments are created within the project directory?
Set the ‘virtualenvs.in-project’ configuration to true using ‘poetry config virtualenvs.in-project true‘.
Can I use Poetry with existing virtual environments?
In fact, Poetry is designed to manage the creation and use of its own virtual environments, though it is possible to manually turn on a targeted virtual environment and perform work with Poetry in it.