WebAssembly for Proxies (AssemblyScript SDK)

This is a friendly fork of https://github.com/Kong/proxy-wasm-assemblyscript-sdk/, temporarily mantained to address an incompatibility between the AssemblyScript SDK and the Rust SDK.

How to use this SDK

Create a new project:

npm init
npm install --save-dev assemblyscript
npx asinit .

Include "use": "abort=abort_proc_exit" to the asconfig.json file as part of the options passed to asc compiler:

{
  "options": {
    "use": "abort=abort_proc_exit"
  }
}

Add "@gcoredev/proxy-wasm-sdk-as": "0.0.1" to your dependencies then run npm install.

Hello, World

Copy this into assembly/index.ts:

export * from "@gcoredev/proxy-wasm-sdk-as/proxy";
import {
  RootContext,
  Context,
  registerRootContext,
  FilterHeadersStatusValues,
  stream_context,
} from "@gcoredev/proxy-wasm-sdk-as";

class AddHeaderRoot extends RootContext {
  createContext(context_id: u32): Context {
    return new AddHeader(context_id, this);
  }
}

class AddHeader extends Context {
  constructor(context_id: u32, root_context: AddHeaderRoot) {
    super(context_id, root_context);
  }
  onResponseHeaders(a: u32, end_of_stream: bool): FilterHeadersStatusValues {
    const root_context = this.root_context;
    if (root_context.getConfiguration() == "") {
      stream_context.headers.response.add("hello", "world!");
    } else {
      stream_context.headers.response.add(
        "hello",
        root_context.getConfiguration()
      );
    }
    return FilterHeadersStatusValues.Continue;
  }
}

registerRootContext((context_id: u32) => {
  return new AddHeaderRoot(context_id);
}, "add_header");

build

To build, simply run:

npm run asbuild

build results will be in the build folder. untouched.wasm and optimized.wasm are the compiled file that we will use (you only need one of them, if unsure use optimized.wasm).

Run

Configure envoy with your filter:

- name: envoy.filters.http.wasm
  config:
    config:
      name: "add_header"
      root_id: "add_header"
      configuration: "what ever you want"
      vm_config:
        vm_id: "my_vm_id"
        runtime: "envoy.wasm.runtime.v8"
        code:
          local:
            filename: /PATH/TO/CODE/build/optimized.wasm
        allow_precompiled: false