smithy-rs-lambda-cdk

This project contains scaffolding to build and deploy a simple Smithy-modeled Rust service in an AWS Lambda fronted by Amazon API Gateway. It can serve as an example to quickly get you started with a smithy-rs service running on AWS Lambda.

It comprises three directories:

• smithy is a Gradle project that builds the model/main.smithy Smithy model using smithy-rs. smithy-rs is used as a Git submodule inside this directory.
  • The model is built using the rust-server-codegen plugin, which produces a server SDK in the form of a Rust crate.
  • The version of smithy-rs used is the one that is pointed to by the Git submodule, defined in .gitmodules. At the moment this points to the smithy-rs-release-0.55.x branch, whose latest version is 0.55.2. This version must also be specified and kept up to date in the model/smithy-build.json file, in the runtimeConfig.versions.DEFAULT key.
• simple-service is the implementation of the actual smithy-rs service, which depends on the generated server SDK crate. It uses the lambda_http and lambda_runtime crates to implement a Lambda handler that receives HTTP requests from API Gateway.
• cdk is an infrastructure-as-code project to deploy the necessary infrastructure to an AWS account. It uses the CDK and is written in TypeScript.

Installation prerrequisites

You will need the following installed:

• Java >= 11.
• Rust toolchain.
• Node >= 18.
• The AWS CDK v2.
• cargo-lambda.

Checking out the repository

Make sure you retrieve the Git submodule when cloning or checking out the repository. The submodule should live under the smithy/smithy-rs directory.

$ git clone --recurse-submodules https://github.com/david-perez/smithy-rs-lambda-cdk.git

Building and deploying

Building comprises three steps.

1. The server SDK needs to be code-generated using smithy-rs.
2. The service using the server SDK needs to be built.
3. The CDK project needs to be built.

The project can then be deployed to an AWS account.

Code-generating the server SDK

$ cd smithy
$ ./gradlew assemble

This should produce the server SDK in the form of a regular Rust crate, simple-service-server-sdk, in the top-level directory. You can build this crate using cargo to ensure the code generation process produced a valid Rust crate:

$ cd simple-service-server-sdk
$ cargo test

Building the service

Build the Rust Lambda function implementing the smithy-rs service in release mode:

$ cd simple-service
$ cargo lambda build --release --x86-64

The binary should appear under target/release. It should be named bootstrap. Copy it over to the target/cdk/release directory, where the CDK will look into:

$ mkdir --parents target/cdk/release
$ cp target/lambda/bootstrap/bootstrap target/cdk/release/bootstrap

Building the CDK project

$ cd cdk
$ npm install
$ npm run build

Deploying the project

The first time you deploy the function, you need to invoke cdk bootstrap. This is to deploy the CDK toolkit stack into an AWS environment, and has nothing to do with the fact that our Rust binary is also named bootstrap.

$ cd cdk
$ cdk bootstrap

To deploy the Lambda function stack, run this command:

$ cdk deploy -y --all

Destroying the project

To destroy the stack:

$ cdk destroy --all