Installing a Flask app can be achieved very easily using the setuptools library of Python. We will have to create a file called setup.py in our application's folder and configure it to run a setup script for our application. It will take care of any dependencies, descriptions, loading test packages, and so on.

The following is an example of a simple setup.py script for our Hello World application:

#!/usr/bin/env python
# -*- coding: UTF-8 -*-
import os
from setuptools import setup

setup(
    name = 'my_app',
    version='1.0',
    license='GNU General Public License v3',
    author='Shalabh Aggarwal',
    author_email='[email protected]',
    description='Hello world application for Flask',
    packages=['my_app'],
    platforms='any',
    install_requires=[
        'flask',
    ],
    classifiers=[
        'Development Status :: 4 - Beta',
        'Environment :: Web Environment',
        'Intended Audience :: Developers',
        'License :: OSI Approved :: GNU General Public License v3',
        'Operating System :: OS Independent',
        'Programming Language :: Python',
        'Topic :: Internet :: WWW/HTTP :: Dynamic Content',
        'Topic :: Software Development :: Libraries :: Python Modules'
    ],
)

In the preceding script, most of the configuration is self-explanatory. The classifiers are used when we make this application available on PyPI. These will help other users search the application using these classifiers.

Now, we can just run this file with the install keyword as shown here:

$ python setup.py install

This will install this application along with all its dependencies mentioned in install_requires, that is, Flask and all the dependencies of Flask as well. Then, this app can be used just like any Python package in our Python environment.