How to install Flask on Ubuntu 21.10

In this tutorial guide, we are going to explore how to install the Flask framework on Ubuntu 21.10.

Flask is a microweb framework written in Python. It is classified as a microframework because it doesn’t require particular libraries or tools. It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions.

Flask depends on jinja template engine and the Werkzeug WSGI toolkit.

Prerequisites

• Flask need Python 3.6 and newer in order to run
• You need to have virtual environment up an running
• Ubuntu 21.10 server up and running.
• Have a user with sudo privileges.

Dependencies

Flask requires the following dependencies.

• Werkzeug. This implements WSGI which is the standard Python interface between applications and servers.
• Jinja. It is a template language that renders the pages to your application data.
• MarkupSafe. It escapes untrusted input when rendering templates to avoid injection attacks.
• ItsDangerous. It securely signs data to ensure data integrity
• Click. This is a framework for writing command line applications

Install Flask on Ubuntu 21.10

1. Run system updates

To install Flask we need to have a virtual environment. To create a virtual environment, let’s first run system updates in order to make all the repositories up to date.

$ sudo apt update && apt upgrade -y

When both updates and upgrades are complete, we can now proceed to create a virtual environment for our project. Check this article on how to create a virtual environment.

How to install Python pip 21 on Ubuntu 21.10

To learn how to install the latest Python, follow this link

How to install Python 3.11 on Ubuntu 20.04

2. Create a virtual environment

To start with let’s first create a project directory.

$ sudo mkdir nextgen
$ cd nextgen 
$ python3 -m venv nextvenv

I know many of you will encounter this error message “The virtual environment was not created successfully because ensurepip is not available. On Debian/Ubuntu systems, you need to install the python3-venv”

What you need to do is to install a virtual environment first. Use the following command to create venv

$ sudo apt install python3.9-venv

You will get the following output.

The following additional packages will be installed:
  python-pip-whl
The following NEW packages will be installed:
  python-pip-whl python3.9-venv
0 upgraded, 2 newly installed, 0 to remove and 0 not upgraded.
Need to get 1902 kB of archives.
After this operation, 2320 kB of additional disk space will be used.
Do you want to continue? [Y/n] y

Press Y and enter to allow installation to continue. When this installation is complete create your virtual environment

3. Activate virtual environment

Before you can use the virtual environment, make sure you activate the virtual environment. Activate with the following command.

$ source nextvenv/bin/activate

Output must look like this

output
(nextvenv) [email protected]:~/nextgen# 

4. Install Flask

Inside the activated virtual environment, you can now install the Flask framework. Run the following command on your terminal.

$ pip install flask

The output will look like this

Collecting flask
  Downloading Flask-2.0.2-py3-none-any.whl (95 kB)
     |████████████████████████████████| 95 kB 7.3 MB/s 
Collecting click>=7.1.2
  Downloading click-8.0.3-py3-none-any.whl (97 kB)
     |████████████████████████████████| 97 kB 15.0 MB/s 
Collecting itsdangerous>=2.0
  Downloading itsdangerous-2.0.1-py3-none-any.whl (18 kB)
Collecting Jinja2>=3.0
  Downloading Jinja2-3.0.3-py3-none-any.whl (133 kB)
     |████████████████████████████████| 133 kB 40.0 MB/s 
Collecting Werkzeug>=2.0
  Downloading Werkzeug-2.0.2-py3-none-any.whl (288 kB)
     |████████████████████████████████| 288 kB 56.1 MB/s 
Collecting MarkupSafe>=2.0
  Downloading MarkupSafe-2.0.1-cp39-cp39-manylinux_2_5_x86_64.manylinux1_x86_64.manylinux_2_12_x86_64.manylinux2010_x86_64.whl (30 kB)
Installing collected packages: MarkupSafe, Werkzeug, Jinja2, itsdangerous, click, flask
Successfully installed Jinja2-3.0.3 MarkupSafe-2.0.1 Werkzeug-2.0.2 click-8.0.3 flask-2.0.2 itsdangerous-2.0.1

You can check the version of Flask you are running with the following command.

$ flask --version
Python 3.9.7
Flask 2.0.2
Werkzeug 2.0.2

I am running Python 3.9.7 which comes preinstalled with Ubuntu 21.10, you don’t need to install it.

5. Conclusion

Congratulations! You have installed Flask and now you are ready to jump into creating awsome projects with Flask. To get started go to Flask getting started page to start writing your Flask project. Happy that you have learned something today. Follow along for more tutorials.