🚀 Rust server side rendering

The crate aims to enable server side rendering on rust servers in the simplest and lightest way possible.

It uses an embedded version of the V8 javascript engine (rusty_v8) to parse and evaluate a built bundle file and return a string with the rendered html.

Note

This project is the backbone of tuono; a fullstack react framework with built in SSR.

Currently it works with Vite, Webpack, Rspack, React 18 and Svelte 4 - Check the examples/ folder.

Check here the benchmark results.

Getting started

Add this to your Cargo.toml:

cargo add ssr_rs

Example

To render to string a bundled react project the application should perform the following calls.

use ssr_rs::Ssr;
use std::fs::read_to_string;

fn main() {
    Ssr::create_platform();

    let source = read_to_string("./path/to/build.js").unwrap();

    let mut js = Ssr::new(&source, "entryPoint").unwrap();

    let html = js.render_to_string(None).unwrap();
    
    assert_eq!(html, "<!doctype html><html>...</html>".to_string());
}

What is the "entryPoint"?

The entryPoint could be either:

the function that returns an object with one or more properties that are functions that when called return the rendered result
the object itself with one or more properties that are functions that when called return the rendered result

In case the bundled JS is an IIFE or the plain object the entryPoint is an empty string.

// IIFE example | bundle.js -> See vite-react example
(() => ({ renderToStringFn: (props) => "<html></html>" }))() // The entryPoint is an empty string

// Plain object example | bundle.js 
({renderToStringFn: (props) => "<html></html>"}); // The entryPoint is an empty string

// IIFE variable example | bundle.js -> See webpack-react example
var SSR = (() => ({renderToStringFn: (props) => "<html></html>"}))() // SSR is the entry point

// Variable example | bundle.js -> See webpack-react example
var SSR = {renderToStringFn: (props) => "<html></html>"}; // SSR is the entry point

The export results are managed by the bundler directly.

Example with initial props

use ssr_rs::Ssr;
use std::fs::read_to_string;

fn main() {
    Ssr::create_platform();

    let props = r##"{
        "params": [
            "hello",
            "ciao",
            "こんにちは"
        ]
    }"##;

    let source = read_to_string("./path/to/build.js").unwrap();

    let mut js = Ssr::new(&source, "entryPoint").unwrap();

    let html = js.render_to_string(Some(&props)).unwrap();

    assert_eq!(html, "<!doctype html><html>...</html>".to_string());
}

Example with actix-web

Examples with different web frameworks are available in the examples folder.

Even though the V8 engine allows accessing the same isolate from different threads that is forbidden by this crate for two reasons:

rusty_v8 library have not implemented yet the V8 Locker API. Accessing Ssr struct from a different thread will make the V8 engine to panic.
Rendering HTML does not need shared state across threads.

For the reasons above parallel computation is a better choice. Following actix-web setup:

use actix_web::{get, http::StatusCode, App, HttpResponse, HttpServer};
use std::cell::RefCell;
use std::fs::read_to_string;

use ssr_rs::Ssr;

thread_local! {
    static SSR: RefCell<Ssr<'static, 'static>> = RefCell::new(
            Ssr::from(
                read_to_string("./client/dist/ssr/index.js").unwrap(),
                "SSR"
                ).unwrap()
            )
}

#[actix_web::main]
async fn main() -> std::io::Result<()> {

    Ssr::create_platform();

    HttpServer::new(|| {
        App::new()
            .service(index)
    })
    .bind("127.0.0.1:8080")?
    .run()
    .await
}

#[get("/")]
async fn index() -> HttpResponse {
    let result = SSR.with(|ssr| ssr.borrow_mut().render_to_string(None).unwrap());

    HttpResponse::build(StatusCode::OK)
        .content_type("text/html; charset=utf-8")
        .body(result)
}

Contributing

Any helps or suggestions will be appreciated.

Known TODOs:

Add examples with other rust backend frameworks
Add examples with other frontend frameworks (i.e. vue, quik, solid)
Add benchmark setup to test against Deno and Bun
Explore support for V8 snapshots
Explore js copilation to WASM (i.e. javy)

License

This project is licensed under the MIT License - see the LICENSE_MIT || LICENSE_APACHE file for more information.

Valerioageno/ssr-rs