The dotenv Package

The dotenv package allows a program to reference Environment Variables from a special file called ".env" in the root directory of the given project, instead of passing them from the command-line.

This file-based approach makes environment variables much easier to manage, especially for Windows users.

Reference: https://github.com/theskumar/python-dotenv.

See also: The os Module for reading environment variables.

Installation

First install the package, if necessary:

pip install python-dotenv # note: NOT just "dotenv"

Usage

To setup this example, create a new directory on your Desktop named "my-secure-project". Then navigate there from the command-line:

cd Desktop/my-secure-project/

Create two files in the "my-secure-project" directory named ".env" and "my_script.py", respectively, and place inside the following contents:

# my-secure-project/.env

SECRET_MESSAGE="Hello World"

# my-secure-project/my_script.py

import os
from dotenv import load_dotenv

load_dotenv() #> loads contents of the .env file into the script's environment

print(os.getenv("SECRET_MESSAGE")) # reads the variable from the environment
#> "Hello World"

And run the script to see the output:

python my_script.py

The lesson is that the load_dotenv() function will load environment variables from the ".env" file into the Python script's environment so they can be accessed via the os module.

Ignoring ".env" Files from Version Control

SECURITY NOTE: Because these ".env" files often contain sensitive information like secret passwords and API Keys, we should absolutely avoid checking them into version control! To do this, we'll use a special ".gitignore" file.

Create another file in the "my-secure-project" directory named ".gitignore", and place inside the following contents:

# my-secure-project/.gitignore

# ignore the ".env" file:
.env

Great! Now all subsequent commits will ignore the ".env" file from your project's version history, so you can push your code to GitHub without divulging your secret credentials.

NOTE: if your repository already contained a ".env" file before you added the corresponding entry to the ".gitignore" file, you'll need to commit the ".gitignore" file then delete / move the ".env" file and make another commit, and then afterwards you can feel free to restore your ".env" file and it will be ignored