cardinal-plugins

The middleware runtime.

What it does

• Tracks builtin middleware (RestrictedRouteMiddleware, etc.) and user-supplied WASM plugins inside PluginContainer.
• Executes middleware chains via PluginRunner, respecting global order and destination-scoped middleware.
• Wraps WASM modules by delegating to cardinal-wasm-plugins.

Adding middleware

Rust

struct MyInbound;

#[async_trait::async_trait]
impl RequestMiddleware for MyInbound {
    async fn on_request(&self, session: &mut Session, backend: Arc<DestinationWrapper>, ctx: Arc<CardinalContext>) -> Result<MiddlewareResult, CardinalError> {
        // inspect/modify session, backend, ctx
        Ok(MiddlewareResult::Continue)
    }
}

Register it by inserting into PluginContainer during bootstrap (either by editing the defaults or supplying a provider factory).

WASM

1. Compile an AssemblyScript or Rust-compiled WASM file.
2. Add it to configuration:

[[plugins]]
wasm = { name = "my-filter", path = "filters/my_filter.wasm" }

The runner validates exports (handle, __new) and executes it in inbound or outbound mode depending on where it’s registered.