aws-lambda-rust-runtime VS tokio

I've been writing more and more about the benefits of Rust and Lambda quite a bit lately and I plan to take advantage of them in this customizer. Additionally, I've leveraged the Lambda Runtime project that includes data structures for the Lambda Events that I'll encounter while working with these payloads.

The Lambda Rust Runtime project bridges that gap between SDK support and enhanced developer experience. Now this code IS flagged as experimental as it is subject to change. Didn't I just say above that I don't like experimental software in production? For something like a critical SDK into AWS, yes. But for something that is mostly data structures and working with different Lambda events, I don't have an issue. I'm comfortable with recommending builders look into this repository. I've also been fortunate to contribute to it and believe that the libraries included will make builder's lives easier. End of the day, if the experimental piece is a hold-up, a Lambda with Rust will be fine without it.

If you are building Rust applications that are deployed in Lambdas, it's well worth your time to check out this AWS project. And nestled inside that repository is a Lambda Events crate that helps with the serde/deserde of different payloads to be encountered when running Lambdas.

Feel free to take look at the GitHub repo and ask any questions you have there, we're always happy to help in what we can: https://github.com/awslabs/aws-lambda-rust-runtime

Rust on Lambda's using containers as the deployment artifact are also very good, i'd say a perfect match. Low artifact size, low cpu+memory usage, fast execution. I think AWS must be using increasingly using Rust on Lambda internally from the talks I've seen them publish and the work gone in to https://github.com/awslabs/aws-lambda-rust-runtime.

For simple REST API's there's not much extra effort in using Rust once you are familiar.

Check out the official AWS Lambda Rust project https://github.com/awslabs/aws-lambda-rust-runtime. It has a bunch of examples and we’ll designed. I got up and running knowing minimal Rust very quickly.

The official https://github.com/awslabs/aws-lambda-rust-runtime seems well architected.

Hi, maybe check out https://github.com/awslabs/aws-lambda-rust-runtime there's some examples in there.. But essentially you can build a Lambda function and deploy to your AWS account with this toolset.

use aws_lambda_events::apigw::{ ApiGatewayCustomAuthorizerRequestTypeRequest, ApiGatewayCustomAuthorizerResponse, ApiGatewayCustomAuthorizerPolicy, IamPolicyStatement, }; use lambda_runtime::{run, service_fn, Error, LambdaEvent}; use serde_json::json; #[tokio::main] async fn main() -> Result<(), Error> { tracing_subscriber::fmt() .with_ansi(false) .without_time() .with_max_level(tracing_subscriber::filter::LevelFilter::INFO) .init(); run(service_fn(function_handler)).await } pub async fn function_handler(event: LambdaEvent) -> Result { // do something with the event payload let method_arn = event.payload.method_arn.unwrap(); // for example we could use the authorization header if let Some(token) = event.payload.headers.get("authorization") { // do something with the token // my custom logic return Ok(custom_authorizer_response( "ALLOW", "some_principal", &method_arn, )); } Ok(custom_authorizer_response( &"DENY".to_string(), "", &method_arn)) } pub fn custom_authorizer_response(effect: &str, principal: &str, method_arn: &str) -> ApiGatewayCustomAuthorizerResponse { let stmt = IamPolicyStatement { action: vec!["execute-api:Invoke".to_string()], resource: vec![method_arn.to_owned()], effect: Some(effect.to_owned()), }; let policy = ApiGatewayCustomAuthorizerPolicy { version: Some("2012-10-17".to_string()), statement: vec![stmt], }; ApiGatewayCustomAuthorizerResponse { principal_id: Some(principal.to_owned()), policy_document: policy, context: json!({ "email": principal }), // https://github.com/awslabs/aws-lambda-rust-runtime/discussions/548 usage_identifier_key: None, } }

FYI, there’s an offical rust “runtime” in the works: https://github.com/awslabs/aws-lambda-rust-runtime

Being able to control nondeterminism is particularly useful for testing and debugging. This allows creating reproducible test environments, as well as discrete-event simulation for faster-than-real-time simulation of time delays. For example, Cardano uses a simulation environment for the IO monad that closely follows core Haskell packages; Sui has a simulator based on madsim that provides an API-compatible replacement for the Tokio runtime and intercepts various POSIX API calls in order to enforce determinism. Both allow running the same code in production as in the simulator for testing.

tokio / hyper / toml / serde / serde_json / json5 / console

tokio - An asynchronous runtime for Rust

3. Tokio

The AWS SDK makes use of the async capabilities in the Tokio library. So when you see async in front of a fn that function is capable of executing asynchronously.

Petar is also looking at implementing concurrency the way it is in Go to have a fully functional virtual machine as it is in the spec. This would likely attract more external contributors to developing the VM. One advantage of Rust is that, with the concurrency model, there is already an extensive library called Tokio which he can use. Petar stresses that this isn’t easy, but he believes it’s achievable, at least as a research topic around determinism and concurrency.

Another thing to point out is that async is a thing in Rust. I'm not going to begin to dive into this paradigm in this article, but know it's handled by the awesome Tokio framework.

So I started by using Tokio, a popular async runtime. The docs and samples helped me get a simple outbound TCP connection working. The Rust async book also had a lot of good explanations, both practical and digging into the details of what a runtime does.

Regarding the quote:

> The Original Sin of Rust async programming is making it multi-threaded by default. If premature optimization is the root of all evil, this is the mother of all premature optimizations, and it curses all your code with the unholy Send + 'static, or worse yet Send + Sync + 'static, which just kills all the joy of actually writing Rust.

Agree about the melodramatic tone. I also don't think removing the Send + Sync really makes that big a difference. It's the 'static that bothers me the most. I want scoped concurrency. Something like <https://github.com/tokio-rs/tokio/issues/2596>.

Another thing I really hate about Rust async right now is the poor instrumentation. I'm having a production problem at work right now in which some tasks just get stuck. I wish I could do the equivalent of `gdb; thread apply all bt`. Looking forward to <https://github.com/tokio-rs/tokio/issues/5638> landing at least. It exists right now but is experimental and in my experience sometimes panics. I'm actually writing a PR today to at least use the experimental version on SIGTERM to see what's going on, on the theory that if it crashes oh well, we're shutting down anyway.

Neither of these complaints would be addressed by taking away work stealing. In fact, I could keep doing down my list, and taking away work stealing wouldn't really help with much of anything.

The PHP <-> Rust bindings are provided by https://github.com/Nicelocal/ext-php-rs/ (our fork of https://github.com/davidcole1340/ext-php-rs with a bunch of UX improvements :).

php-tokio's integrates the https://revolt.run event loop with the https://tokio.rs event loop; async functionality is provided by the two event loops, in combination with PHP fibers through revolt's suspension API (I could've directly used the PHP Fiber API to provide coroutine suspension, but it was a tad easier with revolt's suspension API (https://revolt.run/fibers), since it also handles the base case of suspension in the main fiber).