Wasm Workers Server

Wasm Workers Server (wws) is an HTTP server that runs applications with WebAssembly. These applications are composed by multiple modules, called "handlers" or "functions". Each of these modules is in charge of replying to a specific HTTP path in your application.

The server loads the existing Wasm modules and compatible languages in the current path. The filenames and folders determine the final routes that will be served. This is called "filesystem routing" and is a popular technique. Successful frameworks such as NextJS and Eleventy work in this way.

Here you have an example of running the tool:

$ ls .
index.wasm api

$ wws .
⚙️  Loading routes from: .
🗺  Detected routes:
    - http://127.0.0.1:8080/
      => index.wasm (handler: default)
    - http://127.0.0.1:8080/api/hello
      => api/hello.js (handler: default)
🚀 Start serving requests at http://127.0.0.1:8080

Getting Started

Wasm Workers Server runs almost anywhere. Thanks to its portability, downloading and running it anywhere is quite simple:

curl https://raw.githubusercontent.com/vmware-labs/wasm-workers-server/main/install.sh | bash && \
  wws --help

You will see the help of the server:

Usage: wws [OPTIONS] [PATH]

Arguments:
  [PATH]  Folder to read WebAssembly modules from [default: .]

Options:
      --host <HOSTNAME>  Hostname to initiate the server [default: 127.0.0.1]
  -p, --port <PORT>      Port to initiate the server [default: 8080]
  -h, --help             Print help information
  -V, --version          Print version information

Then, you can download some of our example modules and try them directly:

curl https://raw.githubusercontent.com/vmware-labs/wasm-workers-server/main/examples/js-basic/handler.js \
  -o ./index.js && \
  wws .

The server will start immediately:

⚙️  Loading routes from: .
🗺  Detected routes:
    - http://127.0.0.1:8080/
      => index.js (handler: default)
🚀 Start serving requests at http://127.0.0.1:8080

Now, open your browser at http://127.0.0.1:8080.

Local installation

By default, our install.sh script will place the wws binary in the /usr/local/bin path. If you want to install it in your current path, you can run the installer with the --local option:

curl https://raw.githubusercontent.com/vmware-labs/wasm-workers-server/main/install.sh | bash -s -- --local && \
  ./wws --help

Running in a container

If you don't want to install anything locally you can just run wws from the projects.registry.vmware.com/wasmlabs/containers/wasm-workers-server:latest container image. All you need to do is:

• map a local folder with handlers to /app within the container
• expose port 8080 from the container

Here is how to quickly run a container with an ad-hoc handler from the /tmp/wws-app folder:

mkdir /tmp/wws-app 2>/dev/null;
echo 'addEventListener("fetch", (e) => { return e.respondWith(new Response("Hello from WWS\n"));});' > /tmp/wws-app/index.js;
docker run --rm -v /tmp/wws-app:/app -p 8080:8080 projects.registry.vmware.com/wasmlabs/containers/wasm-workers-server:latest

Language Support

Wasm Workers Server focuses on simplicity. We want you to run handlers (written in different languages) safely in WebAssembly. For interpreted languages, we add different interpreters:

Language	Wasm module	Interpreter
Rust	✅	❌
JavaScript	❌	✅
...	...	...

We will include more interpreters in the future.

JavaScript handlers

The integrated interpreter is based on QuickJS (compiled with the quickjs-wasm-rs crate). The compatible handlers follow the Web Workers API approach. However, not all the Web Workers API is available in these handlers. These are some of the missing features:

• No modules available. Handlers must be a single file
• Fetch API
• Async / Await

We will work on including these features in the future.

Development

Prerequisites

To work with this project you will need to install:

• Rust
• Make

Run the project

After installing the different prerequisites, you can run the development environment with:

$ cargo run -- --help

This command will run the server and look for .wasm and compatible modules (like .js) in the folder you pass via arguments. Check the examples folder to get more information about creating Wasm handlers.

Documentation

• src: includes the source code for the Wasm Workers Server project
• examples: folder to generate different example handlers. Check the README file inside to get more information about how to build those