Environment-based settings in Django

Introduction

Environment-based settings help you keep different configurations for development, testing, and production. This keeps your app safe and easy to manage.

When you want to use different database passwords for development and production.

When you want to turn on debug mode only during development.

When you need to change API keys without changing your code.

When deploying your app to different servers with different settings.

When you want to keep sensitive information out of your code.

Syntax

Django

import os

DEBUG = os.getenv('DJANGO_DEBUG', 'False') == 'True'
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.getenv('DB_NAME'),
        'USER': os.getenv('DB_USER'),
        'PASSWORD': os.getenv('DB_PASSWORD'),
        'HOST': os.getenv('DB_HOST', 'localhost'),
        'PORT': os.getenv('DB_PORT', '5432'),
    }
}

Use os.getenv() to read environment variables safely.

Set default values in os.getenv() to avoid errors if variables are missing.

Examples

This sets DEBUG to True only if the environment variable DJANGO_DEBUG is set to 'True'.

Django

DEBUG = os.getenv('DJANGO_DEBUG', 'False') == 'True'

Reads the secret key from environment or uses a default (not recommended for production).

Django

SECRET_KEY = os.getenv('DJANGO_SECRET_KEY', 'default-secret-key')

Reads allowed hosts as a comma-separated string and converts it to a list.

Django

ALLOWED_HOSTS = os.getenv('DJANGO_ALLOWED_HOSTS', 'localhost').split(',')

Sample Program

This example shows how to read environment variables to set Django settings. It prints the debug mode and database connection info.

Django

import os

# Simulate environment variables for this example
os.environ['DJANGO_DEBUG'] = 'True'
os.environ['DB_NAME'] = 'mydb'
os.environ['DB_USER'] = 'user123'
os.environ['DB_PASSWORD'] = 'pass123'
os.environ['DB_HOST'] = 'db.example.com'
os.environ['DB_PORT'] = '5432'

DEBUG = os.getenv('DJANGO_DEBUG', 'False') == 'True'
DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.getenv('DB_NAME'),
        'USER': os.getenv('DB_USER'),
        'PASSWORD': os.getenv('DB_PASSWORD'),
        'HOST': os.getenv('DB_HOST', 'localhost'),
        'PORT': os.getenv('DB_PORT', '5432'),
    }
}

print(f"DEBUG: {DEBUG}")
print(f"Database Name: {DATABASES['default']['NAME']}")
print(f"Database User: {DATABASES['default']['USER']}")
print(f"Database Host: {DATABASES['default']['HOST']}")

Important Notes

Never commit real secret keys or passwords to your code repository.

Use a .env file or your server's environment settings to manage variables.

Use packages like python-dotenv to load environment variables from a file during development.

Summary

Environment-based settings keep your app flexible and secure.

Use os.getenv() to read variables safely.

Keep secrets out of your code and change settings easily per environment.

Practice

1. What is the main reason to use environment-based settings in a Django project?

easy

A. To keep sensitive data like passwords out of the code

B. To make the app run faster

C. To reduce the number of files in the project

D. To avoid using databases

Solution

1. Step 1: Understand environment-based settings purpose

   They help keep sensitive information like passwords and keys out of the codebase.

2. Step 2: Identify the main benefit

   This improves security and allows easy changes per environment without code edits.

3. Final Answer:

   To keep sensitive data like passwords out of the code -> Option A

4. Quick Check:

   Security = Keep secrets out [OK]

Hint: Environment settings protect secrets outside code [OK]

Common Mistakes:

• Thinking environment settings speed up the app
• Confusing environment settings with file count
• Believing environment settings remove database use

2. Which of the following is the correct way to get an environment variable named SECRET_KEY in Django settings?

easy

A. SECRET_KEY = os.get('SECRET_KEY')

B. SECRET_KEY = os.environ['SECRET_KEY']()

C. SECRET_KEY = os.getenv('SECRET_KEY')

D. SECRET_KEY = getenv('SECRET_KEY')

Solution

1. Step 1: Recall correct function to read environment variables

   Use os.getenv('VAR_NAME') to safely get environment variables.

2. Step 2: Check syntax correctness

   SECRET_KEY = os.getenv('SECRET_KEY') uses correct syntax without extra parentheses or wrong function names.

3. Final Answer:

   SECRET_KEY = os.getenv('SECRET_KEY') -> Option C

4. Quick Check:

   Use os.getenv() for environment variables [OK]

Hint: Use os.getenv('VAR') to read environment variables [OK]

Common Mistakes:

• Adding parentheses after os.environ['VAR']
• Using non-existent os.get() function
• Calling getenv() without os prefix

3. Given this code in settings.py:

import os
DEBUG = os.getenv('DEBUG', 'False') == 'True'

What will be the value of DEBUG if the environment variable DEBUG is not set?

medium

A. Raises an error

B. True

C. None

D. False

Solution

1. Step 1: Understand default value in os.getenv()

   If DEBUG is not set, os.getenv('DEBUG', 'False') returns string 'False'.

2. Step 2: Evaluate comparison to string 'True'

   'False' == 'True' is False, so DEBUG becomes False (boolean).

3. Final Answer:

   False -> Option D

4. Quick Check:

   Unset DEBUG defaults to 'False' string, so boolean False [OK]

Hint: Default string 'False' != 'True' means DEBUG is False [OK]

Common Mistakes:

• Assuming default 'False' string converts to boolean True
• Expecting None when variable is missing
• Thinking code raises error if env var missing

4. You wrote this in settings.py:

import os
SECRET_KEY = os.getenv('SECRET_KEY')
DEBUG = os.getenv('DEBUG', False)

But DEBUG is always True even when you set DEBUG=False in the environment. What is the problem?

medium

A. os.getenv returns strings, so DEBUG is the string 'False', which is truthy

B. os.getenv cannot read boolean environment variables

C. SECRET_KEY must be set before DEBUG

D. You must import dotenv to use os.getenv

Solution

1. Step 1: Understand os.getenv returns strings

   Environment variables are strings, so os.getenv('DEBUG', False) returns string 'False' if set.

2. Step 2: Recognize string 'False' is truthy in Python

   Non-empty strings are True in boolean context, so DEBUG is always True.

3. Final Answer:

   os.getenv returns strings, so DEBUG is the string 'False', which is truthy -> Option A

4. Quick Check:

   Env vars are strings; 'False' string is True in boolean [OK]

Hint: Remember env vars are strings, not booleans [OK]

Common Mistakes:

• Assuming os.getenv returns boolean type
• Thinking import order affects env var reading
• Believing dotenv is required for os.getenv

5. You want to set different database settings for development and production using environment variables. Which approach correctly applies environment-based settings in settings.py?

hard

A. Use if os.environ['ENV'] == 'production' without default and catch exceptions

B. Use os.getenv('ENV') == 'production' to load production DB settings, else development settings

C. Set all DB settings to default values and never change them

D. Hardcode production DB settings and ignore environment variables

Solution

1. Step 1: Use environment variable to detect environment

   Check os.getenv('ENV') to decide if running in production or development.

2. Step 2: Load DB settings conditionally

   Load production DB settings if ENV is 'production', else load development settings.

3. Final Answer:

   Use os.getenv('ENV') == 'production' to load production DB settings, else development settings -> Option B

4. Quick Check:

   Conditional DB config based on ENV variable [OK]

Hint: Use ENV variable to switch settings safely [OK]

Common Mistakes:

• Hardcoding production settings in code
• Not providing default for os.environ access
• Ignoring environment variables for config