Setup a Python Virtual Environment

Description

This article demonstrates how to create and launch a virtual python programming environment.

Virtual environments provide an isolated space on your system for working on Python projects, each with its own set of dependencies.

Creating a virtual environment basically generates a folder that contains a copy of the version of python and pip used to execute the command and a few scripts to make it act as an isolated environment.

Requirements

You should have a non-root user with sudo privileges.

Steps

Complete the following steps.

Setup Python

Most versions of Debian Linux should come with Python 3 pre-isntalled.

Perform a system upgrade to ensure we are using the most up-to-date version:

sudo apt update && sudo apt upgrade -y

Check the version of Python 3 currently installed:

python3 -V

Install pip (if not already installed):

sudo apt install -y python3-pip

Install development tools;

sudo apt install -y build-essential libssl-dev libffi-dev python3-dev

Setup Virtual Environment

Install venv

The venv tool is part of the standard Python 3 library, install it by typing:

sudo apt install -y python-venv

Create a New Virtual environment

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$ mkdir python-project
$ cd python-project
$ python3 -m venv .venv

This will create a .venv folder at the root of your project.

Activate the Virtual environment

Use the source command to execute the activate script located in the .venv folder:

$ source my_virtual_environment/bin/activate

You should now see (.venv) prefixed to your command prompt,

(.venv) user@host:~/python-project$

Test the Virtual Environment

Note: Within the virtual environment, you can use the command python instead of python3, and pip instead of pip3.

Try starting the python interpreter:

(.venv) user@host:~/Dev/python$ python

Deactive the Virtual Environment

Use the following command to deactivate the environment:

(.venv) user@host:~/Dev/python$ deactivate

Install Project Dependencies

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pip3 install flask
pip3 install flask-sqlalchemy

Save Project Dependencies

pip3 freeze > requirements.txt

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