Understanding ScopeDoesNotExistException in AWS Cognito Identity Provider

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Introduction

AWS Cognito Identity Provider (Cognito IDP) is a powerful service that manages user authentication and authorization for your applications. It offers a convenient way to handle user sign-ups, sign-ins, and other security-related tasks. However, while working with Cognito IDP, you may come across an exception called ScopeDoesNotExistException. In this article, we will dive deep into this exception, understand its causes, and explore how to handle it effectively.

Table of Contents

• Understanding AWS Cognito Identity Provider
• What is ScopeDoesNotExistException?
• Causes of ScopeDoesNotExistException
• Handling ScopeDoesNotExistException
• Conclusion
• References

Understanding AWS Cognito Identity Provider

Before delving into the specifics of ScopeDoesNotExistException, let’s have a brief overview of AWS Cognito Identity Provider. Cognito IDP is a fully managed service that enables you to add user authentication and authorization to your applications with ease. It offers features like user sign-up, sign-in, multi-factor authentication, social logins, and more, all backed by robust security protocols.

What is ScopeDoesNotExistException?

ScopeDoesNotExistException is an exception thrown by the com.amazonaws.services.cognitoidp.model package in AWS SDK for Java when an invalid scope is provided during an identity provider authorization request. The exception signifies that the requested scope does not exist for the specified user pool client.

Causes of ScopeDoesNotExistException

This exception occurs primarily due to the following reasons:

1. Incorrect client configuration

When configuring your user pool client, you define the allowed OAuth scopes for the client. If the scope mentioned in the request does not exist in your client configuration, ScopeDoesNotExistException will be thrown.

Consider the following code example:

AdminCreateUserRequest createUserRequest = new AdminCreateUserRequest()
    .withUserPoolId("us-west-2_aBcDeFgH")
    .withUsername("johndoe")
    .withDesiredDeliveryMediums("EMAIL")
    .withUserAttributes(
        new AttributeType().withName("email").withValue("johndoe@example.com")
    );

AdminCreateUserResult createUserResult = cognitoClient.adminCreateUser(createUserRequest);
String username = createUserResult.getUser().getUsername();

try {
    AdminInitiateAuthRequest initiateAuthRequest = new AdminInitiateAuthRequest()
        .withUserPoolId("us-west-2_aBcDeFgH")
        .withClientId("abcdefghijklm123456")
        .withAuthFlow(AuthFlowType.USER_PASSWORD_AUTH)
        .withAuthParameters(
            Map.of(
                "USERNAME", username,
                "PASSWORD", "MyPassword123"
            )
        )
        .withScopes("openid", "email", "phone");  // Invalid scope "phone"

    AdminInitiateAuthResult initiateAuthResult = cognitoClient.adminInitiateAuth(initiateAuthRequest);
    // ...
} catch (ScopeDoesNotExistException e) {
    // Handle the exception
}

In the code above, the AdminInitiateAuthRequest incorrectly specifies a scope called "phone", which is not present in the user pool client’s configuration. This will trigger the ScopeDoesNotExistException, and you can catch it to handle accordingly.

2. Incorrect scope usage

Another common scenario leading to ScopeDoesNotExistException is the misuse of scopes while making authorization requests. Ensure that you provide only the scopes that are configured and valid for the respective user pool client.

Handling ScopeDoesNotExistException

To handle ScopeDoesNotExistException gracefully, you can follow these steps:

1. Catch the exception

Wrap the code block that throws the ScopeDoesNotExistException in a try-catch block and catch the exception. This allows you to handle the exception gracefully and perform specific actions based on your application’s requirements.

try {
    // Code that throws ScopeDoesNotExistException
} catch (ScopeDoesNotExistException e) {
    // Handle the exception
}

2. Provide meaningful feedback to the user

When catching the ScopeDoesNotExistException, extract relevant details from the exception object and provide meaningful feedback to the user. This feedback can help users understand why their request failed and guide them in providing valid scopes.

catch (ScopeDoesNotExistException e) {
    String invalidScope = e.getInvalidScope();
    String validScopes = e.getValidScopes().toString();

    // Inform the user that the provided scope is invalid and suggest valid scopes
    String errorMessage = "Invalid scope: " + invalidScope + ". Available scopes: " + validScopes;
    // Display the error message to the user
}

By extracting the invalid scope and the valid scopes from the exception, you can form a helpful error message for the user.

Conclusion

In this article, we explored the ScopeDoesNotExistException in AWS Cognito Identity Provider. We learned that this exception occurs when an invalid scope is provided during an identity provider authorization request. We discussed the two primary causes of this exception and explored how to handle it effectively.

Remember, providing accurate and valid scopes to your authorization requests is crucial to avoid ScopeDoesNotExistException. By following best practices and incorporating proper error handling, you can ensure a smooth user experience in your applications while working with AWS Cognito Identity Provider.

Did you find this article helpful? Feel free to share your thoughts and suggestions in the comments below!

References

1. AWS Cognito Identity Provider - Official Documentation
2. com.amazonaws.services.cognitoidp.model.ScopeDoesNotExistException - AWS SDK for Java Documentation

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