Concept

• Definition: IAM Roles are AWS identities that provide specific permissions to entities such as AWS services, applications, or users. They are not tied to a specific user or group.
• Key Features:
  • Temporary Credentials: Roles grant temporary access to AWS resources using security tokens, ideal for applications or services that need to access resources without using permanent credentials.
  • Cross-Account Access: Roles allow users or services from one AWS account to access resources in another account without needing to create IAM users in that account.
  • Service Roles: Specific roles that allow AWS services to perform actions on behalf of the user, such as allowing EC2 instances to access S3 buckets.

Example Use Cases:

1. EC2 Instance Role:
   • Purpose: Allows an EC2 instance to access an S3 bucket.
   • Permissions: Grants s3:GetObject for a specific S3 bucket.
   • Usage: Attach this role to an EC2 instance when launching it, enabling the application running on the instance to retrieve files from S3 securely.
2. Cross-Account Role:
   • Purpose: Allows users in Account A to access resources in Account B.
   • Permissions: Grants ec2:DescribeInstances for specific EC2 resources in Account B.
   • Usage: A user from Account A assumes the role in Account B to view EC2 instances without needing separate IAM users.
3. Lambda Execution Role:
   • Purpose: Grants an AWS Lambda function the necessary permissions to access other AWS services.
   • Permissions: Allows logs:CreateLogGroup, logs:CreateLogStream, and logs:PutLogEvents to enable logging.
   • Usage: Attach this role to a Lambda function to allow it to write logs to CloudWatch.

Best Practices:

• Use roles instead of IAM users for applications and services to enhance security.
• Regularly review and refine role permissions based on the principle of least privilege.
• Monitor role usage through AWS CloudTrail to detect any unauthorized access.