Smithy Rust

Smithy code generators for Rust that generate clients, servers, and the entire AWS SDK. The latest unreleased SDK build can be found in aws-sdk-rust/next.

Design documentation

All internal and external interfaces are considered unstable and subject to change without notice.

Setup

1. ./gradlew will setup gradle for you. JDK 17 is required.
2. Running tests requires a working Rust installation. See Rust docs for installation instructions on your platform.

Development

For development, pre-commit hooks make it easier to pass automated linting when opening a pull request. Setup:

brew install pre-commit # (or appropriate for your platform: https://pre-commit.com/)
pre-commit install

Project Layout

• aws: AWS specific codegen & Rust code (signing, endpoints, customizations, etc.) Common commands:
  • ./gradlew :aws:sdk:assemble: Generate (but do not test / compile etc.) a fresh SDK into sdk/build/aws-sdk
  • ./gradlew :aws:sdk:sdkTest: Generate & run all tests for a fresh SDK. (Note that these tests require Go to be installed for FIP support to compile properly)
  • ./gradlew :aws:sdk:{cargoCheck, cargoTest, cargoDocs, cargoClippy}: Generate & run specified cargo command.
• codegen-core: Common code generation logic useful for clients and servers
• codegen-client: Smithy client code generation
• codegen-client-test: Smithy protocol test generation & integration tests for Smithy client whitelabel code
• design: Design documentation. See the design/README.md for details about building / viewing.
• codegen-server: Smithy server code generation
• codegen-server-test: Smithy protocol test generation & integration tests for Smithy server whitelabel code
• examples: A collection of server implementation examples

Testing

Running all of smithy-rs’s tests can take a very long time, so it’s better to know which parts to test based on the changes being made, and allow continuous integration to find other issues when posting a pull request.

In general, the components of smithy-rs affect each other in the following order (with earlier affecting later):

1. rust-runtime
2. codegen and codegen-server
3. aws/rust-runtime
4. aws/codegen-aws-sdk

Some components, such as codegen-client-test and codegen-server-test, are purely for testing other components.

Testing rust-runtime and aws/rust-runtime

To test the rust-runtime crates:

# Run all Rust tests for `rust-runtime/` (from repo root):
cargo test --manifest-path=rust-runtime/Cargo.toml
# Run clippy for `rust-runtime/` (from repo root):
cargo clippy --manifest-path=rust-runtime/Cargo.toml

# Or
cd rust-runtime
cargo test
cargo clippy

To test the aws/rust-runtime crates:

# Run all Rust tests for `aws/rust-runtime/` (from repo root):
cargo test --manifest-path=aws/rust-runtime/Cargo.toml
# Run clippy for `aws/rust-runtime/` (from repo root):
cargo clippy --manifest-path=aws/rust-runtime/Cargo.toml

# Or
cd aws/rust-runtime
cargo test
cargo clippy

Some runtime crates have a additional-ci script that can also be run. These scripts often require cargo-hack and cargo-udeps to be installed.

Testing Client/Server Codegen

To test the code generation, the following can be used:

# Run Kotlin codegen unit tests
./gradlew codegen-core:check
./gradlew codegen-client:check
./gradlew codegen-server:check
# Run client codegen tests
./gradlew codegen-client-test:check
# Run server codegen tests
./gradlew codegen-server-test:check

Several Kotlin unit tests generate Rust projects and compile them. When these fail, they typically output links to the location of the generated code so that it can be inspected.

To look at generated code when the codegen tests fail, check these paths depending on the test suite that’s failing:

• For codegen-client-test: codegen-client-test/build/smithyprojections/codegen-client-test
• For codegen-server-test: codegen-server-test/build/smithyprojections/codegen-server-test

Testing SDK Codegen

See the readme in aws/sdk/ for more information about these targets as they can be configured to generate more or less AWS service clients.

# Run Kotlin codegen unit tests
./gradlew aws:codegen-aws-sdk:check
# Generate an SDK, but do not attempt to compile / run tests. Useful for inspecting generated code
./gradlew :aws:sdk:assemble
# Run all the tests
./gradlew :aws:sdk:sdkTest
# Validate that the generated code compiles
./gradlew :aws:sdk:cargoCheck
# Validate that the generated code passes Clippy
./gradlew :aws:sdk:cargoClippy
# Validate the generated docs
./gradlew :aws:sdk:cargoDoc

The generated SDK will be placed in aws/sdk/build/aws-sdk.

MSRV Policy

The MSRV (Minimum Supported Rust Version) for the crates in this project is stable-2, i.e. the current stable Rust version and the prior two versions. Older versions may work. In rare circumstances our MSRV may exceed stable-2 for security purposes (ex: to update a dependency for a security fix that requires an MSRV bump).

Increasing the MSRV is treated as a minor change rather than a major (breaking) one, per Cargo’s SemVer guidance. The MSRV is not increased automatically; when we do increase it, each affected published crate is versioned accordingly: 1.x crates are increased with a minor release (e.g. 1.4.2 → 1.5.0), and 0.x crates are increased with a patch release (e.g. 0.62.1 → 0.62.2).