When should I use Cognito Identity Pools over adding a user to an account?

Cognito Identity Pools and IAM user accounts in AWS serve similar purposes in terms of granting permissions, but they are used in different scenarios based on the architecture and the specific needs of your application.

Here are some guidelines to help decide when to use Cognito Identity Pools versus directly adding a user to an AWS account and managing permissions via IAM:

Use Cognito Identity Pools When:

Federated Identities: You need to support authentication for users from a variety of sources such as social identity providers (like Google, Facebook, Amazon), SAML-based identity providers, or even your own custom identity provider. Cognito Identity Pools facilitate the integration of these third-party identities into AWS.

Temporary AWS Access: You want to provide your users temporary AWS credentials that allow them to directly interact with AWS services. For example, a mobile app that requires direct access to S3 to upload files. Cognito Identity Pools can grant these credentials based on the identity of the user.

Scalability for Consumers: Your application has a potentially large number of end-users and you need to scale securely and efficiently. Cognito Identity Pools is designed to handle high numbers of users and can efficiently manage their permissions without having to create an IAM user for each one.

Mobile and Web Application Integration: You are developing mobile or web applications that require direct access to AWS services. Cognito provides SDKs and libraries that make it easier to integrate AWS services into these applications.

Use IAM Users When:

Static and Controlled Environment: The users needing access are part of your organization and require stable, long-term access to AWS resources. IAM users are more suitable for employees or systems within your organization that need to interact with AWS over extended periods.

Fine-Grained Access Control: You need sophisticated and detailed access controls that go beyond what Cognito Identity Pools offer. IAM allows for more complex policies and permissions management.

Direct Management and Oversight: You prefer to have direct control over the user credentials and policies, perhaps due to compliance requirements or specific organizational policies.

Automation and Scripts: For automated scripts or tools that require AWS access, using IAM users (or roles) is generally more straightforward and secure. For instance, server-side applications that perform tasks on AWS would fit this model better.

Conclusion In summary, if your application involves external users with potentially varied identity providers and needs temporary, limited access to AWS resources, Cognito Identity Pools is the ideal choice. Conversely, IAM users are better suited for internal organizational use where users require stable, long-term access to AWS resources with complex permission requirements. Both tools have their place in AWS architecture, depending on the specific requirements and user types your application is dealing with.