Haconiwa is a Linux container

• Combine Linux container components from scratch
  • cgroup
  • namespace
  • pivot_root
  • capability, seccomp, ...

Linuxの要素技術を自分で繋ぎ直したのがHaconiwa

CRIU

• Checkpoint and restore of processes (or containers)
  • Dump Rails' process status into files
  • Boot from it -> it's fast!

CRIUはプロセスをファイルにダンプして、そこから再生できるツール

What is Rucy

• Rucy compiles Ruby scripts into special bytecodes
  • The eBPF bytecodes!
  • Rucy = Ruby Compiler = RuC

RucyはRubyスクリプトをeBPFの形式に「コンパイル」する

How is Rucy different from RbBCC?

How are they different? (details)

• Basically, eBPF is moving towards a AOT-compiled ecosystem (BPF CO-RE)
  • So the future is Rucy's side
• RbBCC has a larger coverage of eBPF functions
  • Sufficient enough for learning and small tools

今の潮流はAOTだが、サクッと使う分にはRbBCCの方が機能が多い

WebAssembly

• As you know, a technology for running code in browsers
  • Only browsers?

「なんかブラウザで動くやつ」

WebAssembly is not only for browsers

• Browsers are just "one of the runnable environments"
• Can run everywhere with portable VM
  • envoy, fluent-bit, Containers like youki...
  • even for real embedded systems...

ブラウザ外の「アプリケーション組み込み」が個人的に熱い。
envoy、youki、使ったことありますか？

The "Web" part of WebAssembly

• WebAssembly will probably not be just for the web
• ... Just like eBPF is no longer "Berkeley Packer Filter"

Why Ruby for WebAssembly (again)

• Ruby for WebAssembly, with more "embeddability"
  • Also with the mruby.

違うアプローチをしたい理由があります

Trends

• So-called low-level technologies?
• Linux mania? (it's coincidentally)
• "I tried utilizing ${mysterious_tech} from Ruby!"

「 ${謎技術} をRubyから使ってみた！」

Are you interested in low layers?

• It's even "unknown unknown" from ordinary web application engineers...

普通にWebアプリを作ってる分には隠蔽されていることばかり...

A typical low-layer project...

• Has NO Ruby bindings
• Has NO Ruby sample code
• Just has samples for like Go, Python, C++, and Rust

最近の低レイヤツール、クラウドネイティブミドルウェア、マジでRubyの
サポートがない（個人の感想です）

How am I satisfied with "Getting Started"?

• Understand the essence through Ruby
  • Adapting SOTAs to Ruby == Hack

Rubyサポートを入れるには「本質」が分かってないといけないので勉強になる

Core WebAssembly

• Key specifications:
  • import/export Functions
  • Linear memory
• I'll omit the latter for today...

Linear memoryは線形メモリとも / その話は今日は時間なし...

Making a smallest WebAssembly binary

• Written in C

// sample.c
#include <emscripten.h>

void log_something(int size);

int EMSCRIPTEN_KEEPALIVE calc_plus(int n, int m) {
  log_something(n + m);
  return 0;
}

Compile it with emscripten

$ emcc -o sample.wasm --js-library ./lib.js --no-entry ./sample.c
cache:INFO:  - ok

• ※ lib.js is here

mergeInto(LibraryManager.library, {
    log_something: function(value) { /* TODO */ }
});

Export section

$ wasm-objdump -x -j Export sample.wasm 

sample.wasm:    file format wasm 0x1

Section Details:

Export[10]:
 - memory[0] -> "memory"
 - func[2] <calc_plus> -> "calc_plus"
 - table[0] -> "__indirect_function_table"
 - func[3] <_initialize> -> "_initialize" ...

• Invoke calc_plus() from "browser"

Import section

$ wasm-objdump -x -j Import sample.wasm

sample.wasm:    file format wasm 0x1

Section Details:

Import[1]:
 - func[0] sig=2 <env.log_something> <- env.log_something

• Inject log_something() "browser" function into wasm instance

How to use in browser

const obj = {
  env: {
    // Specify the browser-side function here
    log_something: function(value) {
      let log = "sample wasm! 12 + 34 = " + value.toString();
      document.getElementById("placeholder").innerText = log;
    }
  },
};

WebAssembly.instantiateStreaming(fetch("./sample.wasm"), obj).then(
  (obj) => {
    // Call the function defined in wasm here
    obj.instance.exports.calc_plus(12 + 34);
  },
);

WASI is simple if you understand import/export

• WASI = A set of usable functions to import
  • For cooperation with the system in a nice way

WASI = 「これをimportして使えばシステム操作がええ感じにできるで」
という関数のセット

e.g. Emulating WASI in a browser

• https://github.com/bjorn3/browser_wasi_shim
• Implement the "system call" of random_get in browser JS

random_get(buf: number, buf_len: number) {
    const buffer8 = new Uint8Array(...);
    // omit stuffs...
    for (let i = 0; i < buf_len; i += 65536) {
        crypto.getRandomValues(buffer8.subarray(i, i + 65536));
    }
}

random_get をJSで書いてimportさせればWASMでrandomが使えるということ

What I expect with mruby/edge

• To export Ruby method definitions as they are
• To use imported functions as Ruby-level methods

Code image (to be implemented)

• This doesn't mean it will be implemented exactly this way...

# @export!
# @rbs (Integer) -> Integeer
def fib(n)
  # ...
end

# @import!
# @rbs (String) -> void
def console_log(str) = __imported__!

def _start
  console_log("Hello World " + fib(10).to_s)
end

WebAssembly Component Model

• Refer to interface of Core WASM
  • It's a bit fuzzy - like a C dynamic object
• Be more convenient to "connect" programs and world

Core WASM の仕様は色々余地があるので、型をしっかりし、自動検知や
自動生成にフレンドリーにした感じという理解でOK、だと思う

Tools for the WebAssembly Component Model

• User-friendly typing system
  • WIT format
• Binary specification
  • Canonical ABI
• Toolchains
  • Once the above is generally available

WIT format

world rubyist-kaigi {
    export fib: func(n: i32) -> i32;

    import console_log: func(log: string);
}

• OK, some kinda DSL may be desired

Rubyist的には...

FYI: Understanding by Hands-on

• "手書きで理解するWebAssembly Component Model"
  • (Understanding the WebAssembly Component Model by Hand Assemble)
  • https://nulab.com/ja/blog/nulab/webassembly-component-model/
  • https://nulab.com/ja/blog/nulab/webassembly-component-model-hello-world/

wasmCloud,
Future for example

• https://wasmcloud.com/
• A CNCF Sandbox Project

Example of running mruby/edge (roughly)

use mrubyedge::{mrb_helper, vm::RObject};
// ...
impl Guest for HttpServer {
    fn handle(_request: IncomingRequest, response_out: ResponseOutparam) {
        let write_response = |body: &str| { ... };
        let bin = include_bytes!("./fib.mrb");
        let rite = mrubyedge::rite::load(bin).unwrap();
        let mut vm = mrubyedge::vm::VM::open(rite);
        vm.prelude().unwrap(); //...
        match mrb_helper::mrb_funcall(&mut vm, &top_self, "fib".to_string(), &args) {
            Ok(val) => { write_response(&val) }
            Err(ex) => { dbg!(ex); }
        } //...
    }
}

• https://github.com/udzura/mruby-wasmcloud-http

Creating a WASM binary that contains mruby

$ wash build
   Compiling http-hello-world v0.1.0 (/home/ubuntu/mrubyhttp)
    Finished `release` profile [optimized] target(s) in 0.29s

Component built and signed and can be found at "/../build/http_hello_world_s.wasm"

$ # The mruby binary is embedded
$ strings build/http_hello_world_s.wasm | grep MATZ
MATZ0000IREP

$ wasm-tools component wit build/http_hello_world_s.wasm | head -n 20
package root:component;

world root {
  import wasi:clocks/[email protected];
  // ....

  // entry point
  export wasi:http/[email protected];
}

Running this WASM on wasmCloud

$ wash app deploy wadm.yaml
$ wash app status rust-hello-world

rust-hello-world@ - Deployed                   
  Name                                         Kind           Status    
  http_component                               SpreadScaler   Deployed  
  httpserver -(wasi:http)-> http_component     LinkScaler     Deployed  
  httpserver                                   SpreadScaler   Deployed

$ curl localhost:8080
fib(15) = 610

wasmCloud concepts