wasm

README

WebAssembly Middleware

This component lets you manipulate an incoming request or serve a response with custom logic compiled using the htp-wasm Application Binary Interface (ABI). The handle_request function receives an incoming request and can manipulate it or serve a response as necessary.

Please see the documentation for general configuration.

Generating Wasm

To compile your wasm, you must compile source using an SDK such as http-wasm-guest-tinygo. You can also make a copy of hello.go and replace the handler.HandleFn function with your custom logic.

If using TinyGo, compile like so and set the url attribute to "file://router.wasm":

tinygo build -o router.wasm -scheduler=none --no-debug -target=wasi router.go`

Notes

• This is an alpha feature, so configuration is subject to change.
• This module implements the host side of the http-wasm handler protocol.
• This uses wazero for the WebAssembly runtime as it has no dependencies, nor relies on CGO. This allows installation without shared libraries.
• Many WebAssembly compilers leave memory unbounded and/or set to 16MB. To avoid resource exhaustion, assign concurrency controls.

Documentation

Index

• func NewMiddleware(logger logger.Logger) dapr.Middleware
• type Metadata

Functions

func NewMiddleware

func NewMiddleware(logger logger.Logger) dapr.Middleware

Types

type Metadata

type Metadata struct {
	// GuestConfig is an optional configuration passed to WASM guests.
	// Users can pass an arbitrary string to be parsed by the guest code.
	GuestConfig string `mapstructure:"guestConfig"`
}