rustv1/cross_service/photo_asset_management/README.md
The Photo Asset Management (PAM) example app uses Amazon Rekognition to categorize images, which are stored with Amazon S3 Intelligent-Tiering for cost savings. Users can upload new images. Those images are analyzed with label detection and the labels are stored in an Amazon DynamoDB table. Users can later request a bundle of images matching those labels. When images are requested, they will be retrieved from Amazon Simple Storage Service (Amazon S3), zipped, and the user is sent a link to the zip.
This Rust implementation shows a number of techniques to run Rust binaries in AWS Lambda. The src/bin/pam.rs binary uses the lambda _HANDLER environment variable to choose which handler to use for requests. This is a trade off - while it's a single binary in Amazon S3, each handler only uses a subset of the features. Because there's a lot of overlap in which features are used, and the entire binary is under 5MB, the convenience of a single Code Asset for the AWS Cloud Development Kit (AWS CDK) outweighs managing multiple binaries for this application. Other applications should apply their best judgment for this tradeoff. Individual binaries are available for testing in isolation.
The Common struct loads a number of clients and environment data a single time during Lambda initialization. This is then used for every invocation of the handler. uploader.rs and chunked_uploader.rs export a ZipWriter, which manages reading a number of files from Amazon S3, and then streams them in a .zip to another bucket.
The handlers module includes the specific handler logic.
https://www.cargo-lambda.info/
cargo lambda build --release --arm64
zip ../../target/lambda/pam/bootstrap{.zip,}
Set appropriate environment variables from the AWS CDK in Cargo.toml.
In one terminal, run cargo lambda and watch for changes.
cargo lambda watch
In another terminal, run cargo lambda invoke <name-of-bin> --data-file examples/<name-of-bin>.json.
Follow the instructions in the PAM application CDK README, using PAM_LANG=rust.