How to write reusable middleware for Rust Lambda functions using tower, the generic middleware engine that already underpins the AWS Lambda Rust runtime. Includes a complete DynamoDB-backed IP rate limiter with SAM deployment.

A practical look at using <code>tower</code> as the middleware layer for Rust AWS Lambda functions, with examples that build up to a DynamoDB-backed per-IP rate limiter. It covers <code>Service</code>, <code>Layer</code>, stack ordering, short-circuiting, boxed async futures, and testing middleware without deploying a Lambda. Comments