AWS Assume Role vs. AWS IAM Role

Attribute	AWS Assume Role	AWS IAM Role
Definition	Temporary security credentials that can be assumed by IAM users or AWS services	Permanent set of permissions that define what actions an entity is allowed to perform in AWS
Duration	Can be set to expire after a specified period of time	Does not have an expiration time by default
Usage	Used for cross-account access or to delegate permissions to applications	Assigned to entities within the same AWS account to grant permissions
Trust Relationship	Requires a trust policy that specifies which entities are allowed to assume the role	Does not have a trust relationship as it is directly attached to an entity

Overview

AWS Assume Role and AWS IAM Role are both important features in AWS Identity and Access Management (IAM) that help manage permissions and access control within an AWS environment. While they serve similar purposes, there are key differences between the two that users should be aware of when deciding which to use for their specific use case.

AWS Assume Role

AWS Assume Role is a feature that allows an IAM user to assume the permissions of another role temporarily. This is useful in scenarios where a user needs to access resources or perform actions that are not allowed by their current IAM role. By assuming a different role, the user can temporarily inherit the permissions associated with that role without having to make permanent changes to their own permissions.

When using AWS Assume Role, the user must have permission to assume the role, which is typically granted through a trust policy. The trust policy defines which IAM users or roles are allowed to assume the role, adding an extra layer of security to the process. Once the user assumes the role, they can perform actions based on the permissions granted to that role.

One key advantage of AWS Assume Role is that it allows for cross-account access, meaning a user in one AWS account can assume a role in another account to access resources or perform actions. This can be useful in scenarios where organizations have multiple AWS accounts and need to manage permissions across them.

AWS IAM Role

AWS IAM Role, on the other hand, is a feature that defines a set of permissions for a specific entity within an AWS account. This entity can be an IAM user, an AWS service, or an external user or application. IAM roles are used to define what actions the entity is allowed to perform on AWS resources.

When creating an IAM role, users can define a trust policy that specifies which entities are allowed to assume the role. This helps control who can access the permissions associated with the role and adds an extra layer of security to the IAM role. IAM roles can also have policies attached to them that define the specific permissions granted to the entity assuming the role.

One key advantage of AWS IAM Role is that it allows for fine-grained control over permissions within an AWS account. Users can create multiple IAM roles with different sets of permissions to ensure that entities have the appropriate level of access to resources. IAM roles can also be used in conjunction with other AWS services, such as AWS Lambda functions or Amazon EC2 instances, to grant permissions to these services.

Comparison

While both AWS Assume Role and AWS IAM Role are important features in AWS IAM, there are some key differences between the two. AWS Assume Role is used for temporary permission escalation, allowing users to assume the permissions of another role for a limited time. This is useful for scenarios where users need to access resources or perform actions that are not allowed by their current IAM role.

On the other hand, AWS IAM Role is used to define a set of permissions for a specific entity within an AWS account. IAM roles are used to control what actions the entity is allowed to perform on AWS resources and can have policies attached to them that define the specific permissions granted to the entity.

One key difference between the two is that AWS Assume Role allows for cross-account access, while AWS IAM Role is limited to the AWS account in which it is created. This means that AWS Assume Role can be useful in scenarios where organizations have multiple AWS accounts and need to manage permissions across them.

Another difference is that AWS Assume Role is temporary in nature, while AWS IAM Role is permanent. When a user assumes a role using AWS Assume Role, they only have the permissions of that role for a limited time before reverting back to their original permissions. In contrast, entities assuming an IAM role have the permissions associated with that role until the role is deleted or the permissions are changed.

Overall, both AWS Assume Role and AWS IAM Role are important features in AWS IAM that serve different purposes. Users should consider their specific use case and requirements when deciding which feature to use for managing permissions and access control within their AWS environment.