Environment variables for secrets in Django - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Django settings snippet?

Given the following Django settings code that reads a secret key from environment variables, what will be the value of SECRET_KEY if the environment variable DJANGO_SECRET_KEY is not set?

Django

import os

SECRET_KEY = os.getenv('DJANGO_SECRET_KEY', 'default_secret')
print(SECRET_KEY)

A default_secret

B '' (empty string)

C None

D Raises KeyError

💡 Hint

Check what os.getenv returns when the environment variable is missing and a default is provided.

The os.getenv function returns the value of the environment variable if it exists. If it does not exist, it returns the default value provided as the second argument. Here, since DJANGO_SECRET_KEY is not set, it returns 'default_secret'.

❓ component_behavior

intermediate

How does Django behave when SECRET_KEY is set from environment variables?

If you set SECRET_KEY = os.environ['DJANGO_SECRET_KEY'] in your Django settings and the environment variable DJANGO_SECRET_KEY is missing, what happens when you run the server?

Django

import os

SECRET_KEY = os.environ['DJANGO_SECRET_KEY']

A Django uses an empty string as SECRET_KEY

B Django raises a KeyError and stops running

C Django uses a default secret key automatically

D Django logs a warning but continues with a random key

💡 Hint

What does os.environ['VAR'] do if VAR is not set?

Accessing os.environ['DJANGO_SECRET_KEY'] raises a KeyError if the environment variable is not set. This stops Django from running because SECRET_KEY is required.

🔧 Debug

advanced

Why does this Django app fail to load the secret key from environment variables?

Consider this snippet in settings.py:

import os

SECRET_KEY = os.getenv('DJANGO_SECRET_KEY')

if not SECRET_KEY:
    raise Exception('Missing SECRET_KEY environment variable')

The app crashes with the exception even though the environment variable is set. What is the most likely cause?

Django

import os

SECRET_KEY = os.getenv('DJANGO_SECRET_KEY')

if not SECRET_KEY:
    raise Exception('Missing SECRET_KEY environment variable')

A The environment variable is set but empty string, which is falsy

B os.getenv cannot read environment variables in Django

C SECRET_KEY is set but the code has a syntax error

D The environment variable name is case-insensitive and mismatched

💡 Hint

Check what happens if the environment variable exists but is empty.

If the environment variable DJANGO_SECRET_KEY is set but empty, os.getenv returns an empty string, which is falsy in Python. The condition if not SECRET_KEY triggers, raising the exception.

📝 Syntax

advanced

Which option correctly loads a secret key from environment variables with a fallback in Django?

Choose the correct Python code snippet to load SECRET_KEY from the environment variable DJANGO_SECRET_KEY with a fallback value 'fallback_secret' if the variable is not set.

A SECRET_KEY = os.environ['DJANGO_SECRET_KEY'] or 'fallback_secret'

B SECRET_KEY = os.environ.get('DJANGO_SECRET_KEY', 'fallback_secret')

C SECRET_KEY = os.getenv('DJANGO_SECRET_KEY', 'fallback_secret')

D SECRET_KEY = os.getenv('DJANGO_SECRET_KEY') ?? 'fallback_secret'

💡 Hint

Check Python syntax for getting environment variables with default values.

Option C uses os.getenv with a default value, which is the correct and idiomatic Python syntax. Option C uses os.environ.get, which is also valid and equivalent since os.getenv is a shorthand for it, but A uses the dedicated function. Option C will raise a KeyError if the variable is missing. Option C uses invalid syntax (?? is not Python).

🧠 Conceptual

expert

Why is it recommended to use environment variables for Django secrets instead of hardcoding them?

Select the best reason why using environment variables for secrets like SECRET_KEY is preferred over hardcoding them in Django settings.

A It allows Django to automatically rotate secrets without code changes

B It makes the app run faster by loading secrets from memory

C It enables secrets to be stored in the database securely

D It keeps secrets out of source code, reducing risk if code is shared or published

💡 Hint

Think about security and code sharing.

Using environment variables keeps sensitive data like SECRET_KEY out of the source code. This prevents accidental exposure if the code is shared publicly or stored in version control. Options B, C, and D are incorrect because environment variables do not affect app speed, automatic rotation, or database storage.