WASM Guest Examples for sgl-model-gateway

This directory contains example WASM middleware components demonstrating how to implement custom middleware for sgl-model-gateway using the WebAssembly Component Model.

Examples Overview

wasm-guest-auth

API key authentication middleware that validates API keys for requests to /api and /v1 paths.

Features:

• Validates API keys from Authorization header or x-api-key header
• Returns 401 Unauthorized for missing or invalid keys
• Attach point: OnRequest only

Use case: Protect API endpoints with API key authentication.

wasm-guest-logging

Request tracking and status code conversion middleware.

Features:

• Adds tracking headers (x-request-id, x-wasm-processed, x-processed-at, x-api-route)
• Converts 500 errors to 503 for better client handling
• Attach points: OnRequest and OnResponse

Use case: Request tracing and error status code conversion.

wasm-guest-ratelimit

Rate limiting middleware with configurable limits.

Features:

• Rate limiting per identifier (API Key, IP, or Request ID)
• Default: 60 requests per minute
• Returns 429 Too Many Requests when limit exceeded
• Attach point: OnRequest only

Note: This is a simplified demonstration with per-instance state. For production, use router-level rate limiting with shared state.

Use case: Protect against request flooding and abuse.

Quick Start

Each example includes its own README with detailed build and deployment instructions. See individual example directories for:

• Build instructions
• Deployment configuration
• Customization options
• Testing examples

Common Prerequisites

All examples require:

• Rust toolchain (latest stable)
• wasm32-wasip2 target: rustup target add wasm32-wasip2
• wasm-tools: cargo install wasm-tools
• sgl-model-gateway running with WASM enabled (--enable-wasm)

Building All Examples

cd examples/wasm
for example in wasm-guest-auth wasm-guest-logging wasm-guest-ratelimit; do
  echo "Building $example..."
  cd $example && ./build.sh && cd ..
done

Deploying Multiple Modules

You can deploy all three modules together:

curl -X POST http://localhost:3000/wasm \
  -H "Content-Type: application/json" \
  -d '{
    "modules": [
      {
        "name": "auth-middleware",
        "file_path": "/path/to/wasm_guest_auth.component.wasm",
        "module_type": "Middleware",
        "attach_points": [{"Middleware": "OnRequest"}]
      },
      {
        "name": "logging-middleware",
        "file_path": "/path/to/wasm_guest_logging.component.wasm",
        "module_type": "Middleware",
        "attach_points": [{"Middleware": "OnRequest"}, {"Middleware": "OnResponse"}]
      },
      {
        "name": "ratelimit-middleware",
        "file_path": "/path/to/wasm_guest_ratelimit.component.wasm",
        "module_type": "Middleware",
        "attach_points": [{"Middleware": "OnRequest"}]
      }
    ]
  }'

Modules execute in the order they are deployed. If a module returns Reject, subsequent modules won't execute.