How to Install Flask in Python

Flask is a popular Python module used for web development. It’s simple to use and great for beginners. Flask can also act as a third-party plugin or be used for creating prototypes. It’s made up of various libraries and modules to help build web applications. Flask is fully written in Python, unlike Django. Since Flask is based on Python, you need to have Python installed on your system before you can install Flask.

In this tutorial, we’ll explore how to install Flask in Python using step-by-step instructions.

Prerequisites

You must fulfill the following prerequisites for installing Flask in Python:

• Python3 must be pre-installed.
• The latest pip version must be pre-installed.
• python3-venv for creating isolated Python environments.

You can install Flask in Python in a code editor like VS Code or PyCharm to write and manage your Flask project.

Installing Flask in Python

You can install Flask in Python by setting up and activating a virtual environment, then using pip to install Flask. Let’s go through the following stepwise instructions to learn how to install Flask in Python:

Step 1: Set up a Virtual Environment

Let’s execute the below-given command to install the python3-venv package:

sudo apt install python3-venv

This package provides tools to create isolated Python 3 virtual environments:

Step 2: Create a Virtual Environment

Now set up a project directory named ultahost by executing the command below:

mkdir ultahost

Let’s access the ultahost directory by running the following command:

cd ultahost

After this, we use the virtualenv command to create a new isolated Python environment named venv: 

virtualenv venv

Step 3: Activate the Virtual Environment

After setting up a virtual environment using virtualenv, you can activate it by running the following command:

source ./venv/bin/activate

Step 4: Check if Python PIP is Installed

Once the virtual environment is activated, you can proceed with the Flask installation. However, it’s recommended to check the pip version using the following command to ensure you’re using the correct version for your environment:

pip -V

If you are using an outdated PIP version, refer to this guide to upgrade the PIP to the latest version.

Step 5: Install Flask in Python

Now that everything is set up, you can install Flask in Python using pip as follows:

pip install flask

Step 6: Run Flask

Let’s open the Python interpreter by running the following command: 

python

In the Python interactive shell, run the following command to import Flask:

import flask

If Flask is installed in Python, this command runs successfully without throwing any error. However, if Flask is not installed, you’ll encounter a Module not found error:

That’s all about installing Flask in Python.

Conclusion

Flask is a popular, lightweight Python web framework known for its simplicity and ease of use in building web applications. Installing Flask in Python is a straightforward process that involves setting up a virtual environment, ensuring the necessary prerequisites are in place, and using pip to install Flask. In this article, we explained how to install Flask in Python using step-by-step instructions.

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