WASM Logging Example for sgl-model-gateway

This example demonstrates logging and tracing middleware for sgl-model-gateway using the WebAssembly Component Model.

Overview

This middleware provides:

Request Tracking - Adds tracking headers (x-request-id, x-wasm-processed, x-processed-at, x-api-route)
Status Code Conversion - Converts 500 errors to 503

Quick Start

Build and Deploy

bash

# Build
cd examples/wasm-guest-logging
./build.sh

# Deploy (replace file_path with actual path)
curl -X POST http://localhost:3000/wasm \
  -H "Content-Type: application/json" \
  -d '{
    "modules": [{
      "name": "logging-middleware",
      "file_path": "/absolute/path/to/wasm_guest_logging.component.wasm",
      "module_type": "Middleware",
      "attach_points": [{"Middleware": "OnRequest"}, {"Middleware": "OnResponse"}]
    }]
  }'

Customization

Modify on_request or on_response functions in src/lib.rs to add custom tracking headers or status code conversions.

Testing

bash

# Check tracking headers
curl -v http://localhost:3000/v1/models 2>&1 | \
  grep -E "(x-request-id|x-wasm-processed|x-processed-at)"

# Test status code conversion (requires endpoint returning 500)
curl -v http://localhost:3000/some-endpoint 2>&1 | grep -E "(< HTTP|500|503)"

Troubleshooting

Verify module attached to both OnRequest and OnResponse phases
Check router logs for execution errors
Ensure module built successfully