Rust runtime for Vercel Functions.
Community-maintained package to support using Rust inside Vercel Functions as a Runtime.
First, you'll need a vercel.json
file in your project:
{
"functions": {
"api/**/*.rs": {
"runtime": "vercel-rust@latest"
}
}
}
A Vercel Function will be created for every file that matches api/**/*.rs
. Next, you can create a new Function api/user.rs
:
use http::{StatusCode};
use vercel_lambda::{lambda, error::VercelError, IntoResponse, Request, Response};
use std::error::Error;
fn handler(_: Request) -> Result<impl IntoResponse, VercelError> {
let response = Response::builder()
.status(StatusCode::OK)
.header("Content-Type", "text/plain")
.body("Hello World")
.expect("Internal Server Error");
Ok(response)
}
// Start the runtime with the handler
fn main() -> Result<(), Box<dyn Error>> {
Ok(lambda!(handler))
}
Finally, we need an api/Cargo.toml
file:
[package]
name = "index"
version = "1.0.0"
authors = ["Your Name <[email protected]>"]
edition = "2018"
[dependencies]
http = "0.1"
vercel_lambda = "*"
[lib]
name = "util"
path = "_util.rs"
Note: Cargo.toml
must exist on the same level as the .rs
files.
This Builder supports installing dependencies defined in the Cargo.toml
file.
Furthermore, more system dependencies can be installed at build time with the presence of a shell build.sh
file in the same directory as the entrypoint file.
With vercel dev
and vercel-rust
, you can develop your Rust-based lamdas on your own machine.
During local development with vercel dev
, ensure rust
and cargo
are already installed and available in your PATH
, since they will not be installed automatically. The recommended way to install rust
and cargo
on your machine is with rustup.
Since this project contains both Rust and Node.js code, you need to install the relevant dependencies. If you're only working on the JavaScript side, you only need to install those dependencies (and vice-versa).
# install node dependencies
npm install
# install cargo dependencies
cargo fetch
Are cargo workspaces supported?
Not quite. Cargo's workspaces feature is a great tool when working on multiple binaries and libraries in a single project. If a cargo workspace is found in the entrypoint, however, vercel-rust
will fail to build.
To get around this limitation, create build entries in your vercel.json
file for each Cargo.toml
that represents a Function within your workspace. In your .vercelignore
, you'll want to add any binary or library project folders that aren't needed for your lambdas to speed up the build process like your Cargo.toml
workspace.
It's also recommended to have a Cargo.lock
alongside your lambda Cargo.toml
files to speed up the build process. You can do this by running cargo check or a similar command within each project folder that contains a lambda.
If you have a compelling case for workspaces to be supported by vercel-rust
which are too cumbersome with this workaround, please submit an issue! We're always looking for feedback.
Can I use musl/static linking?
Unfortunately, the AWS Lambda Runtime for Rust relies (tangentially) on proc_macro
, which won't compile on musl targets. Without musl
, all linking must be dynamic. If you have a crate that relies on system libraries like postgres
or mysql
, you can include those library files with the includeFiles
config option and set the proper environment variables, config, etc. that you need to get the library to compile.
For more information, please see this issue.