Requirements File
Create a requirements.txt file and place it in the top-level directory of your source bundle. A typical Python application will have dependencies on other third-party Python packages. In Python, pip is the standard way of installing packages. Pip has a feature that allows you to specify all the packages you need (as well as their versions) in a single requirements file. For more information about the requirements file, go to Requirements File Format. The following is an example requirements.txt file for Django.
Django==1.11.3 MySQL-python==1.2.5
In your development environment, you can use the pip freeze command to generate your requirements file.
~/my-app$pip freeze > requirements.txt
To ensure that your requirements file only contains packages that are actually used
by your application, use a virtual environment that only has those packages installed. Outside of a virtual environment, the output
of
pip freeze will include all pip packages installed on your development machine, including those
that came with your operating
system.