rust-lambda-build

AWS Lambda Rust — Build

Compile the Rust Lambda function using Cargo Lambda.

Context from $ARGUMENTS

• Target architecture: x86_64 (default) or arm64 (AWS Graviton2)
• Output format: binary (default) or .zip (needed for AWS CLI / SAM deployment)

Step 1: Ensure Cargo Lambda is installed

cargo lambda --version

If not found, install it:

cargo install cargo-lambda

Step 2: Build the function

Standard release build (x86_64):

cargo lambda build --release

For AWS Graviton2 (ARM64) — recommended for better price/performance:

cargo lambda build --release --arm64

Build a .zip deployment package (required for AWS CLI or SAM deployment):

cargo lambda build --release --output-format zip

Build .zip for ARM64:

cargo lambda build --release --arm64 --output-format zip

Step 3: Locate the output

After a successful build:

• Binary: target/lambda/<function-name>/bootstrap
• Zip package: target/lambda/<function-name>/bootstrap.zip

The compiled binary is named bootstrap — this is the required executable name for Lambda custom runtimes (provided.al2023).

Important notes

• Rust Lambda functions use the provided.al2023 OS-only runtime (not a managed runtime like python3.12 or nodejs20.x)
• The entire function compiles into a single executable containing your code and all dependencies — no separate layers needed
• Do NOT use Lambda layers for Rust dependencies — include everything in the deployment package
• After a successful build, run /rust-lambda:deploy or /rust-lambda:invoke to test locally

Troubleshooting common build errors

• Missing cross-compilation toolchain: On macOS/Windows building for Linux, Cargo Lambda handles cross-compilation automatically via Docker or Zig. Ensure Docker is running or Zig is installed.
• Dependency version conflicts: Run cargo update and retry.
• edition = "2024" errors: Ensure you're using a recent Rust toolchain (rustup update stable).