Access Environment Variables in Python

Table of Contents

• Using os Module
• Handling Sensitive Information with os.environ
• Using python-dotenv Package
• Organizing Environment Variables with configparser
• Accessing Variables with sys and Config Variables
• Conclusive Summary
• References

Using os Module

The os module in Python is a standard utility that interfaces with the operating system. Through os, you can access environment variables easily:

import os

# Access an environment variable
DB_USER = os.getenv('DB_USER')
DB_PASS = os.environ.get('DB_PASSWORD')

# Set an environment variable
os.environ['DB_HOST'] = 'localhost'

This method is straightforward and does not require additional packages.

Handling Sensitive Information with os.environ

Sensitive data such as API keys and database passwords should be stored securely. The os.environ dictionary can be used to access such sensitive information:

import os

# Access a sensitive environment variable
SECRET_KEY = os.environ['SECRET_API_KEY']

# Raises a KeyError if the key doesn't exist
try:
    SECRET_KEY = os.environ['SECRET_API_KEY']
except KeyError:
    print('The SECRET_API_KEY environment variable is not set.')

Using python-dotenv Package

(python-dotenv) is a Python package that reads key-value pairs from a .env file and sets them as environment variables:

from dotenv import load_dotenv
load_dotenv()

import os

# Now you can safely access the variables
DB_USER = os.getenv('DB_USER')

Organizing Environment Variables with configparser

Python’s configparser module can be used to read configuration files, which can function similarly to environment variables:

from configparser import ConfigParser

config = ConfigParser()
config.read('settings.ini')

# Accessing variables
DB_USER = config['database']['DB_USER']

Accessing Variables with sys and Config Variables

sys module allows accessing command-line parameters, which can be utilized for passing configuration.

import sys

# Access system arguments
if '--db-user' in sys.argv:
    DB_USER = sys.argv[sys.argv.index('--db-user') + 1]

Conclusive Summary

In this tutorial, we discussed various methods to access environment variables in Python, which included using the os module, securing sensitive information, utilizing the python-dotenv package, organizing variables with configparser, and leveraging sys for command-line inputs. Each method has its own use cases, and choosing the right one depends on the needs of your application and its operating environment.

References

• os — Miscellaneous operating system interfaces — Python 3.10.2 documentation
• python-dotenv
• configparser — Configuration file parser — Python 3.10.2 documentation
• sys — System-specific parameters and functions — Python 3.10.2 documentation