Cognito for user authentication in AWS - Mini Project: Build & Apply

Cognito for user authentication

📖 Scenario: You are building a simple web application that needs user login and registration. To manage users securely, you will use AWS Cognito, a service that handles user authentication and user pools.

🎯 Goal: Create an AWS Cognito User Pool with basic settings to enable user sign-up and sign-in.

📋 What You'll Learn

Create a Cognito User Pool named exactly MyUserPool

Set the User Pool to allow email as a sign-in alias

Enable self sign-up for users

Configure password policy to require a minimum length of 8 characters

Add an app client named exactly MyUserPoolClient without generating a client secret

💡 Why This Matters

🌍 Real World

AWS Cognito is widely used to manage user authentication securely without building your own login system.

💼 Career

Understanding how to configure Cognito user pools is essential for cloud engineers and developers working on secure web and mobile applications.

1

Create the Cognito User Pool resource

Create an AWS Cognito User Pool resource named MyUserPool using AWS CloudFormation syntax. Set the pool name to MyUserPool.

AWS

# Define the AWS::Cognito::UserPool resource named MyUserPool
# Your code here

Hint

Use AWS CloudFormation syntax to define a resource of type AWS::Cognito::UserPool with the name MyUserPool.

2

Configure sign-in aliases and enable self sign-up

Add properties to the MyUserPool resource to allow users to sign in using their email address. Also enable self sign-up by setting AllowAdminCreateUserOnly to false.

AWS

Resources:
  MyUserPool:
    Type: AWS::Cognito::UserPool
    Properties:
      UserPoolName: MyUserPool
      # Add sign-in aliases and self sign-up settings here
      # Your code here

Hint

Set UsernameAttributes and AutoVerifiedAttributes to email. To enable self sign-up, set AllowAdminCreateUserOnly to false under AdminCreateUserConfig.

3

Set password policy for the user pool

Add a password policy to the MyUserPool resource that requires a minimum password length of 8 characters.

AWS

Resources:
  MyUserPool:
    Type: AWS::Cognito::UserPool
    Properties:
      UserPoolName: MyUserPool
      UsernameAttributes:
        - email
      AutoVerifiedAttributes:
        - email
      AdminCreateUserConfig:
        AllowAdminCreateUserOnly: false
      # Add password policy here
      # Your code here

Hint

Under Policies, add PasswordPolicy with MinimumLength set to 8.

4

Create an app client for the user pool

Create an AWS Cognito User Pool Client resource named MyUserPoolClient linked to the MyUserPool. Do not generate a client secret.

AWS

Resources:
  MyUserPool:
    Type: AWS::Cognito::UserPool
    Properties:
      UserPoolName: MyUserPool
      UsernameAttributes:
        - email
      AutoVerifiedAttributes:
        - email
      AdminCreateUserConfig:
        AllowAdminCreateUserOnly: false
      Policies:
        PasswordPolicy:
          MinimumLength: 8
  # Define the User Pool Client MyUserPoolClient here
  # Your code here

Hint

Define a resource of type AWS::Cognito::UserPoolClient named MyUserPoolClient. Set UserPoolId to reference MyUserPool and GenerateSecret to false.

Practice

1. What is the main purpose of AWS Cognito in user authentication?

easy

A. To manage user sign-up and sign-in securely

B. To store application data in the cloud

C. To create virtual servers for applications

D. To monitor network traffic

Solution

1. Step 1: Understand AWS Cognito's role

   AWS Cognito is designed to handle user authentication, including sign-up and sign-in processes securely.

2. Step 2: Compare options with Cognito's function

   Options A, B, and D describe other AWS services or functions unrelated to user authentication.

3. Final Answer:

   To manage user sign-up and sign-in securely -> Option A

4. Quick Check:

   Cognito = User sign-up/sign-in management [OK]

Hint: Remember: Cognito = user login management [OK]

Common Mistakes:

• Confusing Cognito with storage services
• Thinking Cognito manages servers
• Mixing Cognito with network monitoring

2. Which AWS Cognito component stores and verifies user information?

easy

A. Identity pool

B. User pool

C. Lambda function

D. API Gateway

Solution

1. Step 1: Identify the component for user data

   User pools in Cognito are designed to store and verify user information like usernames and passwords.

2. Step 2: Eliminate unrelated components

   Identity pools provide temporary AWS credentials, Lambda runs code, and API Gateway manages APIs, none store user info.

3. Final Answer:

   User pool -> Option B

4. Quick Check:

   User pool = stores user info [OK]

Hint: User pool = user info storage and verification [OK]

Common Mistakes:

• Confusing identity pool with user pool
• Thinking Lambda stores user data
• Mixing API Gateway with user management

3. Given this AWS CLI command:
aws cognito-idp create-user-pool-client --user-pool-id us-east-1_123456789 --client-name MyAppClient
What does this command do?

medium

A. Lists all user pools

B. Creates a new user pool

C. Deletes a user pool client

D. Creates a new user pool client for an existing user pool

Solution

1. Step 1: Analyze the command action

   The command uses 'create-user-pool-client' which creates a client app for an existing user pool identified by --user-pool-id.

2. Step 2: Understand the client role

   User pool clients connect apps to user pools for login; this command does not create or delete user pools themselves.

3. Final Answer:

   Creates a new user pool client for an existing user pool -> Option D

4. Quick Check:

   create-user-pool-client = new client for user pool [OK]

Hint: Look for 'create-user-pool-client' to identify client creation [OK]

Common Mistakes:

• Confusing client creation with user pool creation
• Assuming deletion instead of creation
• Misreading the command as a list operation

4. You wrote this code snippet to authenticate a user with Cognito but get an error:

client = boto3.client('cognito-idp')
response = client.initiate_auth(
    ClientId='abc123',
    AuthFlow='USER_PASSWORD_AUTH',
    AuthParameters={'USERNAME': 'user1'}
)

What is missing to fix the error?

medium

A. Add 'PASSWORD' in AuthParameters

B. Change AuthFlow to 'ADMIN_NO_SRP_AUTH'

C. Remove ClientId parameter

D. Add 'SECRET_HASH' in AuthParameters

Solution

1. Step 1: Check required AuthParameters for USER_PASSWORD_AUTH

   This flow requires both 'USERNAME' and 'PASSWORD' parameters to authenticate.

2. Step 2: Identify missing parameter

   The code only provides 'USERNAME' but misses 'PASSWORD', causing the error.

3. Final Answer:

   Add 'PASSWORD' in AuthParameters -> Option A

4. Quick Check:

   USER_PASSWORD_AUTH needs USERNAME and PASSWORD [OK]

Hint: USER_PASSWORD_AUTH needs both username and password [OK]

Common Mistakes:

• Forgetting to include password in parameters
• Changing AuthFlow unnecessarily
• Removing ClientId which is required

5. You want to allow users to sign in with social providers like Google using AWS Cognito. Which setup is required?

hard

A. Use only an identity pool without a user pool

B. Create only a user pool client without identity providers

C. Configure a user pool with identity providers and set up an identity pool for AWS credentials

D. Set up Lambda triggers to handle social login manually

Solution

1. Step 1: Understand social login with Cognito

   Social login requires configuring user pools with external identity providers like Google.

2. Step 2: Connect user pool to identity pool for AWS credentials

   Identity pools provide AWS credentials after authentication; both are needed for full setup.

3. Final Answer:

   Configure a user pool with identity providers and set up an identity pool for AWS credentials -> Option C

4. Quick Check:

   Social login = user pool + identity pool setup [OK]

Hint: Social login needs user pool + identity pool configured [OK]

Common Mistakes:

• Skipping identity providers in user pool
• Using only identity pool without user pool
• Trying to handle social login only with Lambda