Hands-On Serverless Computing

Resource-based policies (Lambda function policies)

Every Lambda function can have resource-based permission policies associated with it. For Lambda, the function itself is the primary resource, and then there are function-level policies called Lambda function policies, through which you can grant permissions such as having Amazon S3 invoke your AWS Lambda function as soon as a new object is created in the bucket. You can achieve this by just adding/granting permissions to your AWS Lambda function policy, instead of creating a new IAM role. It is very important to note that Lambda function policies are only used when you are setting up an event source in your Lambda function to grant a service such as Amazon S3 to invoke your Lambda function. ...