markmansour / hello-world-rust-lambda

hello-world-rust-lambda

"Hello, World" in Rust, deployed to AWS Lambda

Goals

To learn about:

• Rust - how to build a hello world application. The basics of the Rust toolchain (cargo, etc)
• How to deploy a non-standard language to Lambda

Disclaimer: This is my first Rust project (I wrote my first Hello World Rust program only a few hours before starting this). This is a learning project. This isn't an example of my finest coding or my amazing documentation skills. This project is for me.

Helpful posts

• Rust Runtime for AWS Lambda
• Lambda execution role

Getting Started

Prereqs.

1. Install Rust/Cargo.
2. Install the AWS CLI. Run aws configure. See "Creating an execution role in the IAM console" for details on creating the appropriate role.

Generate scaffolding

Use Cargo to generate scaffolding.

cargo new hello-world-rust-lambda

Update the code

Update src/main.rs

use lambda_runtime::{service_fn, LambdaEvent, Error};
use serde_json::{json, Value};

#[tokio::main]
async fn main() -> Result<(), Error> {
    let func = service_fn(func);
    lambda_runtime::run(func).await?;
    Ok(())
}

async fn func(event: LambdaEvent<Value>) -> Result<Value, Error> {
    let (event, _context) = event.into_parts();
    let first_name = event["firstName"].as_str().unwrap_or("world");

    Ok(json!({ "message": format!("Hello, {}!", first_name) }))
}

Update the dependencies

Update Cargo.toml

[dependencies]
lambda_runtime = "0.8.2"
serde_json = "1.0.107"
tokio = "1.32.0"

Build

Build for AWS servers / X86 Linux (not my Apple M2 mac). By default it builds for X86.

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

Deploy the function to the Lambda service:

aws lambda create-function --function-name hello-rust-world --handler bootstrap --zip-file fileb://./target/lambda/hello-world-rust-lambda/bootstrap.zip --runtime provided.al2 --role arn:aws:iam::264225025302:role/lambda_execution --environment Variables={RUST_BACKTRACE=1} --tracing-config Mode=Active

Test the invocation from the CLI:

aws lambda invoke --cli-binary-format raw-in-base64-out --function-name hello-rust-world --payload '{"firstName": "Mark"}' output.json