Hands-On Serverless Computing

AWS Lambda permissions model

For an AWS Lambda (FaaS)-based serverless application to work, you need to manage various permissions and access to resources, for example:

• For event sources, you would have to grant the event source such as Amazon S3 permissions so that it can invoke your AWS Lambda function. The exceptions here are for stream-based services such as Amazon DynamoDB streams and Amazon Kinesis Data Streams.

• For stream-based event sources such as Amazon DynamoDB streams and Amazon Kinesis Data Streams, your AWS Lambda function will itself polls and pull the streams on your behalf, and read new records on the stream. Because of this, you have to grant the AWS Lambda function permissions for the relevant actions on the stream. ...