Prerequisite

Python 2.6 or higher is usually required for installation of Flask. Although Flask and its dependencies work well with Python 3 (Python 3.3 onwards), many Flask extensions do not support it properly. Hence, it is recommended that Flask should be installed on Python 2.7.

Install virtualenv for development environment

virtualenv is a virtual Python environment builder. It helps a user to create multiple Python environments side-by-side. Thereby, it can avoid compatibility issues between the different versions of the libraries.

The following command installs virtualenv

pip install virtualenv

This command needs administrator privileges. Add sudo before pip on Linux/Mac OS. If you are on Windows, log in as Administrator. On Ubuntu virtualenv may be installed using its package manager.

Sudo apt-get install virtualenv

Once installed, new virtual environment is created in a folder.

mkdir newproj
cd newproj
virtualenv venv

To activate corresponding environment, on Linux/OS X, use the following −

venv/bin/activate

On Windows, following can be used

venvscriptsactivate

We are now ready to install Flask in this environment.

pip install Flask

The above command can be run directly, without virtual environment for system-wide installation.