The comparison of user pools and identity pools in Amazon Cognito

Amazon Cognito is a service provided by AWS for managing user authentication and access for mobile and web applications. Within Cognito, there are two primary components that facilitate different aspects of user identity and access management: User Pools and Identity Pools. Understanding the differences between these two is key for AWS Certified Developer – Associate (DVA-C02) exam candidates and for effectively utilizing them in applications.

User Pools

Amazon Cognito User Pools are user directories that provide sign-up and sign-in options for your app users. User Pools are used to manage and authenticate users, enabling them to sign in directly with a username and password or through third-party identity providers like Google, Facebook, or Amazon.

Key Features:

• User registration and directory management
• Standard sign-in with a username or email and password
• Social sign-in with federated identities from Facebook, Google, Amazon, etc.
• Security features such as multi-factor authentication (MFA) and account recovery
• Customizable workflows and user experience through Lambda triggers

Example Use Case:

A web application with its own user management system where users can register, sign-in, and manage their profiles.

Identity Pools

Amazon Cognito Identity Pools, also known as Federated Identities, enable developers to grant their users temporary AWS credentials to access AWS services directly from the client. They act as an identity broker between your users and AWS services.

Key Features:

• Temporary AWS credentials to access AWS resources
• Unauthenticated access for guest users
• Direct federation with external identity providers like SAML and OpenID Connect, or through an existing User Pool
• Fine-grained access control using AWS IAM roles and policies

Example Use Case:

A mobile app where users upload files to an S3 bucket and access other AWS services.

Comparison of User Pools and Identity Pools

Integrating User Pools and Identity Pools

Often, developers make use of both User Pools and Identity Pools to manage user access in a comprehensive way. A typical pattern involves using a User Pool for authenticating users and an Identity Pool to authorize authenticated users to access AWS resources.

Code Example

When developing applications, you might write code that interacts with both Cognito User Pools and Identity Pools. Below is a pseudo-code snippet illustrating how you might authenticate a user with a User Pool and obtain AWS credentials with an Identity Pool:

// Assume AWS SDK and Cognito SDK are already set up and configured

// Authenticate with User Pool
cognitoUser.authenticateUser(authenticationDetails, {
onSuccess: (session) => {
// User is authenticated, get the ID token
let idToken = session.getIdToken().getJwtToken();

// Now get AWS credentials using the Identity Pool
AWS.config.credentials = new AWS.CognitoIdentityCredentials({
IdentityPoolId: ‘us-west-2:12345678-1234-1234-1234-1234567890ab’,
Logins: {
‘cognito-idp.us-west-2.amazonaws.com/us-west-2_abcdefghi’: idToken
}
});

// Refresh AWS credentials
AWS.config.credentials.refresh((error) => {
if (error) {
console.error(error);
} else {
// Now the user has AWS credentials and can access allowed AWS resources
// For example, accessing S3
let s3 = new AWS.S3();
// Perform S3 operations like uploading a file, listing buckets, etc.
}
});
},
onFailure: (err) => {
console.error(err);
}
});

In the example above, Cognito User Pools handle the initial user authentication, and upon success, the obtained token is used to request temporary AWS credentials from the Identity Pool based on the defined IAM roles.

Understanding the differences and synergies between User Pools and Identity Pools is crucial for AWS developers. By effectively using these services, developers can secure applications, manage user identities, and provide appropriate access to AWS resources.