How to Read Environment Variables in Python

Python’s os module provides simple access to environment variables, which is essential for 12-factor app configuration and secrets management. Environment variables are the standard way to configure applications without hardcoding sensitive data.

Basic usage:

import os

# Get environment variable with default
database_url = os.getenv('DATABASE_URL', 'sqlite:///default.db')
api_key = os.getenv('API_KEY')

if api_key:
    print("API key found")
else:
    print("Warning: API_KEY not set")

Reading with error handling:

import os

try:
    required_config = os.environ['REQUIRED_CONFIG']
    print(f"Config: {required_config}")
except KeyError:
    print("Error: REQUIRED_CONFIG environment variable not set")
    exit(1)

Reading multiple variables:

import os

config = {
    'debug': os.getenv('DEBUG', 'False').lower() == 'true',
    'port': int(os.getenv('PORT', '8000')),
    'database_url': os.getenv('DATABASE_URL', 'sqlite:///app.db'),
    'secret_key': os.environ.get('SECRET_KEY')
}

print(f"Running on port {config['port']}")