Centralized vs distributed auth in Microservices - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to specify the component responsible for user authentication in a centralized auth system.

Microservices

auth_service = [1]()  # This service handles all user login requests centrally

Drag options to blanks, or click blank then click option'

ALoadBalancer

BUserDB

CCache

DAuthServer

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a database or cache as the auth handler instead of a dedicated auth server.

The AuthServer is the centralized component that handles all authentication requests in a centralized authentication system.

2fill in blank

medium

Complete the code to represent a token verification step in a distributed auth system.

Microservices

if service.verify_token([1]):
    grant_access()

Drag options to blanks, or click blank then click option'

Ajwt_token

Bpassword

Cuser_credentials

Dsession_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using raw passwords or credentials instead of tokens for verification.

In distributed authentication, services verify a JWT token locally to grant access without contacting a central server.

3fill in blank

hard

Fix the error in the code that incorrectly tries to validate tokens in a distributed system by calling a central auth service synchronously.

Microservices

def authenticate(token):
    token = [1].validate_token(token)
    return token

Drag options to blanks, or click blank then click option'

ACentralAuthService

BLocalTokenVerifier

CCacheService

DDatabaseConnector

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the central auth service synchronously causing delays and bottlenecks.

In distributed auth, authentication should be done locally by verifying tokens, not by synchronous calls to a central service. LocalTokenVerifier handles this.

4fill in blank

hard

Fill both blanks to complete the code that shows how a distributed auth system validates a token and extracts user info.

Microservices

if [1].validate([2]):
    user = [1].extract_user([2])

Drag options to blanks, or click blank then click option'

ATokenService

BAuthServer

Cjwt_token

Duser_credentials

Attempts:

3 left

💡 Hint

Common Mistakes

Using user credentials instead of tokens for validation in distributed auth.

The TokenService validates the jwt_token locally and extracts user information in distributed authentication.

5fill in blank

hard

Fill all three blanks to complete the code that demonstrates centralized auth issuing a token after verifying credentials.

Microservices

def login(user_input):
    if [1].verify([2]):
        return [3].issue_token([2])
    else:
        return None

Drag options to blanks, or click blank then click option'

ACentralAuthService

Buser_input

CTokenIssuer

DLocalTokenVerifier

Attempts:

3 left

💡 Hint

Common Mistakes

Using local token verification or wrong variable names in centralized auth flow.

In centralized authentication, the CentralAuthService verifies the user_input credentials and the TokenIssuer issues a token upon success.

Practice

1. What is the main characteristic of centralized authentication in microservices?

easy

A. No authentication is required between services

B. Each microservice verifies user identity independently

C. Authentication is done by the client application only

D. A single service handles all user login and identity verification

Solution

1. Step 1: Understand centralized authentication

   Centralized authentication means one dedicated service manages all login and identity checks for the system.

2. Step 2: Compare with other options

   Distributed auth where each service verifies independently, client-only auth, or no auth are not centralized.

3. Final Answer:

   A single service handles all user login and identity verification -> Option D

4. Quick Check:

   Centralized auth = single service [OK]

Hint: Centralized means one place handles all auth [OK]

Common Mistakes:

• Confusing centralized with distributed auth
• Thinking each service handles login in centralized auth
• Assuming client-only authentication is centralized

2. Which of the following is a typical token used in distributed authentication?

easy

A. OAuth 2.0 access token

B. SQL query string

C. HTML cookie without signature

D. Plain text password

Solution

1. Step 1: Identify token types in distributed auth

   Distributed authentication commonly uses tokens like OAuth 2.0 access tokens to verify identity without contacting a central service each time.

2. Step 2: Eliminate incorrect options

   SQL queries, unsigned cookies, and plain text passwords are not secure tokens used for distributed auth.

3. Final Answer:

   OAuth 2.0 access token -> Option A

4. Quick Check:

   Distributed auth token = OAuth 2.0 token [OK]

Hint: OAuth tokens are standard for distributed auth [OK]

Common Mistakes:

• Confusing SQL queries with tokens
• Using unsigned cookies as secure tokens
• Thinking plain text passwords are tokens

3. Consider a microservice system where each service validates JWT tokens locally without contacting a central auth server. What is the main advantage of this approach?

medium

A. Reduced latency and less dependency on a central service

B. Simpler token revocation management

C. Centralized control over user sessions

D. No need for token expiration

Solution

1. Step 1: Understand local JWT validation

   When services validate JWT tokens locally, they avoid network calls to a central auth server, reducing latency and dependency.

2. Step 2: Analyze other options

   Token revocation is harder locally, centralized control over user sessions is lost, and tokens still need expiration.

3. Final Answer:

   Reduced latency and less dependency on a central service -> Option A

4. Quick Check:

   Distributed auth local validation = less latency [OK]

Hint: Local token checks speed up requests [OK]

Common Mistakes:

• Assuming token revocation is easier locally
• Thinking local validation means centralized control
• Ignoring token expiration needs

4. A microservice system uses centralized authentication but experiences frequent downtime of the auth service. What is the best way to fix this issue?

medium

A. Use plain text passwords for faster login

B. Remove authentication completely

C. Implement caching of authentication tokens in services

D. Make each service validate tokens independently without central auth

Solution

1. Step 1: Identify problem with centralized auth downtime

   Downtime of the central auth service causes failures in login or token validation.

2. Step 2: Choose a solution to reduce dependency

   Caching tokens locally in services reduces calls to the central auth, improving availability without removing auth or security.

3. Final Answer:

   Implement caching of authentication tokens in services -> Option C

4. Quick Check:

   Fix downtime by caching tokens [OK]

Hint: Cache tokens to reduce auth service calls [OK]

Common Mistakes:

• Removing authentication entirely
• Switching to insecure plain text passwords
• Switching to distributed auth without planning

5. You are designing a large microservices system that requires high security and low latency. Which authentication approach best balances these needs?

hard

A. Centralized authentication with synchronous calls for every request

B. Distributed authentication using signed tokens validated locally with periodic revocation checks

C. No authentication to maximize speed

D. Centralized authentication with no token expiration

Solution

1. Step 1: Analyze security and latency needs

   High security requires token validation and revocation; low latency requires avoiding frequent central calls.

2. Step 2: Evaluate options

   Distributed authentication using signed tokens validated locally with periodic revocation checks uses signed tokens validated locally to reduce latency and periodic revocation checks to maintain security. Centralized authentication with synchronous calls for every request causes latency, no authentication is insecure, and centralized authentication with no token expiration risks stale sessions.

3. Final Answer:

   Distributed authentication using signed tokens validated locally with periodic revocation checks -> Option B

4. Quick Check:

   Balance security and speed with distributed tokens [OK]

Hint: Use local token checks plus revocation for security and speed [OK]

Common Mistakes:

• Choosing no authentication for speed
• Ignoring token expiration and revocation
• Relying on central auth for every request causing latency