In this article, you’ll learn how to get started with virtual environments in Python, in both Windows and Linux operating systems.
When you start working on multiple projects in your local development environment, you’ll often run into dependency issues. Creating virtual environments for each of your projects can help you manage dependencies and project requirements better.
To leverage the advantage of virtual environments in Python, let’s learn to create and activate virtual environments. 👩🏽💻
What Are Virtual Environments?
Virtual environments are isolated and independent environments that contain the code and dependencies of a project.
But why should you use virtual environments?
Well, virtual environments allow you to install and use different versions of the same libraries for various projects. Using virtual environments also ensures that there are no breaking changes when two or more projects use different versions. Let’s understand this in greater detail.
Installing Packages in Python
The Python standard library ships with several useful modules for unit testing, interacting with the operating system, working with dates and times, and more.
However, when working on Python projects, you’ll often need to install other packages – developed by the Python community. This is especially true for applications such as web scraping for data collection, machine learning, and web applications.
To install and manage these packages, you can use conda or pip.
Each project requires a specific set of packages that you need to install. However, when you install all the packages in your development environment on your local machine, all the projects share the globally installed packages.
So why is this a problem?
Well, you may have N packages in your development environment. However, the project that you are working on currently may require only 3 of them. When all your projects share common installations, it is very difficult to identify which of the projects required which of the installed packages – the dependencies associated with each project.
There’s another limitation to this approach. Suppose you have a Django 2.2 project in your project library. You decide to start working on a project that uses Django 4. So you install the most recent version of Django in the same development environment.
What happens to the existing installation?
It is removed and replaced by the version of Django you installed. With newer stable releases, certain features might have been deprecated. And your earlier Django projects may not work as expected.
Summing up our discussion thus far: dependency management becomes difficult when the packages are all installed in a common environment because the projects require their own set of libraries to run.
How Virtual Environments Work
So far, we have seen the challenges associated with installing packages in a global development environment (system-wide installations). This motivates us to understand how virtual environments address this limitation.
When you create and activate a virtual environment for your Python projects, you can install only those packages that are required for the current project.
Revisiting the Django projects example, with virtual environments, you can have both Django 2.2 and Django 4 projects run – without any conflict. This is because the Django installations are no longer system-wide installations but are confined to the virtual environments of the respective projects.
In essence: virtual environments are isolated environments that contain both the code and the dependencies for a project.
Advantages of Virtual Environments
Now that you’ve learned how virtual environments work in Python, let’s enumerate the advantages of using them:
Virtual environments provide an isolated development environment for individual projects allowing us to install only the packages needed by required for the specific project.
As the virtual environments of projects are both independent and isolated, different projects can use different versions of the same library—depending on the requirements. With virtual environments, you don’t have to worry about system permissions to install libraries and set up the development environment.
Once you install packages in a virtual environment, you can capture the project’s dependencies in a requirements.txt file. This allows other developers to replicate the project’s development and environment, and install the required packages using a single command.
Tools to Create Virtual Environments
So far, you’ve learned how virtual environments work and the advantages of using them. Let’s explore some popular tools you can use to create and manage virtual environments in Python.
Virtualenv is one of the widely used tools for creating and managing virtual environments for Python projects. A subset of the functionality of virtualenv is available in the venv package. However, the virtualenv package is faster and extensible as compared to venv.
With pipnev, you have both the virtual environment functionality of virtualenv and package management capabilities of pip. It uses manages pipfiles to manage project dependencies inside of a virtual environment using.
Poetry is a package management tool that lets you manage dependencies across all Python projects. To start using Poetry, you need to have Python 3.7 or a later version installed.
As mentioned, venv offers a subset of the functionality of virtualenv but it comes with the advantage that it is built into the Python standard library, starting from Python 3.3.
It is readily available with the Python installation—and does not require installation of external packages. We’ll use it in this tutorial to create and work with virtual environments. ✅
How to Create a Python Virtual Environment in Ubuntu
💬 To follow along with the remainder of this tutorial, you need to have a local installation of Python 3. Ensure that you’re running Python 3.5 or a later version.
This section outlines the steps to create and activate virtual environments in an Ubuntu Linux machine. The same steps can be used on other Linux distros as well.
For easier management, let’s create a project directory and cd into it; We’ll create venv inside this directory.
$ mkdir my_project
$ cd my_project
The general syntax to create a virtual environment for your Python project is python3 -m venv <venv-name-or-path>. Upon running this command a virtual environment called my_env will be created in the current working directory:
$ python3 -m venv my_env
How to Activate and Install Packages Inside a Virtual Environment
After you’ve created the virtual environment, you can activate it and install required packages in it. To activate virtual environment you can run the following command:
$ source my_env/bin/activate
Once you’ve activated a virtual environment, you can run the pip list command to get the list of installed packages:
$ pip list
So far we’ve not installed any package, so you should be able to see setuptools and pip—installed by default—in each of the created virtual environments.
The installation of pip inside the virtual environment allows you to install packages needed for the specific project; this is why you have an independent development environment for each project.
Now that you have activated the virtual environment, you can install project-specific packages in it using pip. As an example, let us install Python requests, one of the most downloaded Python packages, which provides several useful features to send HTTP requests for working with web APIs.
$ pip install requests
When you install the requests library, you’ll see that the requests library gets installed along with all the packages that are required by it.
$ pip list
You can use the pip freeze command and redirect the output to a requirements.txt file, as shown:
$ pip freeze > requirements.txt
If you examine the contents of the current project directory, you’ll see that the requirements.txt file has been created.
# my_env requirements.txt
You can deactivate the virtual environment after you’ve worked on the project by running the following command:
How to Create a Python Virtual Environment in Windows
In general, a Linux environment is preferred for development. If you’re on a Windows machine, you can consider using the Windows Subsystem for Linux (WSL) to set up an Ubuntu terminal environment for local development.
If you’re on a Windows machine, you can use either the Windows PowerShell or the Command Prompt and create virtual environments using the following command:
> python -m venv <path-to-venv>
How to Activate a Virtual Environment
Activating virtual environments on a Windows machine is different depending on whether you’re working on the command prompt or the Windows PowerShell.
If you are on the command prompt, run the following command to activate the virtual environment:
Alternatively, if you’re using Windows PowerShell, running this command will activate the virtual environment:
You can install all the required packages inside the virtual environment.
To deactivate virtual environments, you can run the deactivate command—both on the command prompt and Windows PowerShell.
In this article, we discussed the limitations of system-wide installations and how they make dependency management across Python projects difficult. Virtual environments in Python provide a way to manage dependencies better while providing an isolated development environment for individual projects.
Among the widely used tools for creating and managing virtual environments in Python, you’ve learned how to use venv – that is built into the Python standard library to create and activate virtual environments.
Inside a project’s dedicated virtual environment, versions of libraries specific to a project can be installed. These requirements can then be captured in a requirements.txt file, which allows other developers to replicate the project environment easily.
When you start your next Python project, be sure to use virtual environments for better dependency management. Happy coding!🎉
Bala Priya C
Bala Priya is a developer and technical writer from India with over three years of experience in the technical content writing space. She shares her learning with the developer community by authoring tech tutorials, how-to guides, and more…. read more