Alibaba Cloud Service Mesh:Tulis plug-in Wasm dalam Rust untuk proxy Envoy di ASM

Buat proyek

Buat direktori bernama rust-example, masuk ke direktori tersebut, lalu inisialisasi library Rust baru:

mkdir rust-example && cd rust-example
cargo init --lib

Konfigurasikan dependensi

Ganti isi file Cargo.toml dengan berikut ini:

[package]
name = "rust-example"
version = "0.1.0"
edition = "2021"

[lib]
# Build sebagai dynamic library yang kompatibel dengan C agar Envoy dapat memuatnya
crate-type = ["cdylib"]

[dependencies]
log = "0.4.8"
proxy-wasm = "0.2.2"

Jenis crate cdylib menghasilkan dynamic library yang kompatibel dengan runtime Wasm. Dua dependensi tersebut adalah:

• log — Fasad logging standar Rust untuk output log terstruktur.

• proxy-wasm — Proxy-Wasm Rust SDK, yang menyediakan definisi trait dan binding fungsi host.

Implementasikan logika plug-in

Plug-in perlu:

1. Mendaftarkan RootContext yang memberi tahu Envoy bahwa plug-in ini menangani traffic HTTP.

2. Untuk setiap permintaan HTTP masuk, membuat HttpContext yang memeriksa header permintaan.

3. Pada callback on_http_request_headers, periksa header allow: true. Blokir permintaan dengan HTTP 403 jika header tidak ada, atau izinkan jika ada.

Ganti isi file src/lib.rs dengan:

use log::info;
use proxy_wasm::traits::*;
use proxy_wasm::types::*;

proxy_wasm::main! {{
    proxy_wasm::set_log_level(LogLevel::Trace);
    proxy_wasm::set_root_context(|_| -> Box<dyn RootContext> { Box::new(HttpHeadersRoot) });
}}

struct HttpHeadersRoot;

// Warisi fungsi utilitas bersama (akses properti, pengatur waktu, dll.)
impl Context for HttpHeadersRoot {}

impl RootContext for HttpHeadersRoot {
    fn get_type(&self) -> Option<ContextType> {
        Some(ContextType::HttpContext)
    }

    fn create_http_context(&self, context_id: u32) -> Option<Box<dyn HttpContext>> {
        Some(Box::new(HttpHeaders { context_id }))
    }
}

struct HttpHeaders {
    context_id: u32,
}

impl Context for HttpHeaders {}

impl HttpContext for HttpHeaders {
    fn on_http_request_headers(&mut self, _: usize, _: bool) -> Action {
        info!("#{} wasm-rust: on_http_request_headers", self.context_id);

        match self.get_http_request_header("allow") {
            Some(allow) if allow == "true" => {
                Action::Continue
            }
            _ => {
                info!("#{} wasm-rust: allow header not found or is not true, deny by default", self.context_id);
                self.send_http_response(
                    403,
                    vec![("Content-Type", "text/plain")],
                    Some(b"Forbidden by ASM Wasm Plugin, rust version\n"),
                );
                Action::Pause
            }
        }
    }
}

Penjelasan kode:

Kompilasi plug-in

Build plug-in dengan target wasm32-wasi:

cargo build --target wasm32-wasi --release

Setelah build berhasil, binari Wasm tersedia di:

target/wasm32-wasi/release/rust_example.wasm

Aktifkan logging debug

Gunakan kubeconfig kluster bidang data untuk mengaktifkan log debug Wasm pada Pod gerbang:

kubectl -n istio-system exec <gateway-pod-name> -c istio-proxy -- \
  curl -XPOST "localhost:15000/logging?wasm=debug"

Ganti <gateway-pod-name> dengan nama aktual Pod gerbang Anda.

Uji tanpa header allow

Kirim permintaan tanpa header allow:

curl <ASM-gateway-IP>/status/418

Output yang diharapkan:

Forbidden by ASM Wasm Plugin, rust version

Plug-in memblokir permintaan dan mengembalikan HTTP 403.

Periksa log gerbang

Periksa log Pod gerbang untuk entri seperti berikut:

2024-09-05T08:33:31.079869Z  info  envoy wasm  wasm log istio-system.header-authorization: #2 wasm-rust: on_http_request_headers
2024-09-05T08:33:31.079943Z  info  envoy wasm  wasm log istio-system.header-authorization: #2 wasm-rust: allow header not found or is not true, deny by default
{"authority_for":"xx.xx.xx.xx","bytes_received":"0","bytes_sent":"43","downstream_local_address":"xx.xx.xx.xx:80","downstream_remote_address":"xx.xx.xx.xx:xxxxx","duration":"0","istio_policy_status":"-","method":"GET","path":"/status/418","protocol":"HTTP/1.1","request_id":"d5250d1a-54b3-406d-8bea-5a51b617b579","requested_server_name":"-","response_code":"403","response_flags":"-","route_name":"httpbin","start_time":"2024-09-05T08:33:31.079Z","trace_id":"-","upstream_cluster":"outbound|8000||httpbin.default.svc.cluster.local","upstream_host":"-","upstream_local_address":"-","upstream_response_time":"-","upstream_service_time":"-","upstream_transport_failure_reason":"-","user_agent":"curl/8.9.0-DEV","x_forwarded_for":"xx.xx.xx.xx"}

Baris log ini mengonfirmasi bahwa plug-in telah dieksekusi dan menolak permintaan.

Uji dengan header allow

Kirim permintaan dengan allow: true:

curl <ASM-gateway-IP>/status/418 -H "allow: true"

Output yang diharapkan:

    -=[ teapot ]=-

       _...._
     .'  _ _ `.
    | ."` ^ `". _,
    \_;`"---"`|//
      |       ;/
      \_     _/
        `"""`

Permintaan diteruskan ke HTTPBin, yang mengembalikan respons teapot HTTP 418 standar. Plug-in berfungsi dengan benar.