---
tags:
- ml-intern
---
# Alpine Embeddings

Run embedding models locally on **Alpine Linux** in Docker using **Node.js** — zero Python, zero glibc, pure WASM inference.

## What is this?

A lightweight REST API that generates text embeddings using transformer models. Runs entirely in a ~100MB Docker container on Alpine Linux with no native dependencies.

| Feature | Detail |
|---------|--------|
| **Runtime** | Node.js 20 on Alpine Linux |
| **Inference** | ONNX Runtime (WASM backend) via `@xenova/transformers` |
| **Model** | `Xenova/bge-small-en-v1.5` (384 dimensions, 32MB) |
| **API** | REST (Express.js) |
| **Image size** | ~150MB |
| **Startup** | ~5s (model loads from cache) |
| **Latency** | ~50-100ms per embedding |

## Quick Start

```bash
# Clone
git clone https://huggingface.co/asusf15/alpine-embeddings
cd alpine-embeddings

# Build
docker build -t embeddings .

# Run
docker run -p 3000:3000 embeddings
```

Server starts on `http://localhost:3000`. Model loads automatically on first boot (~5s).

## API

### `POST /embed`

Generate embeddings for text.

**Request:**
```json
{"text": "Hello world"}
```

**Batch request:**
```json
{"text": ["Hello world", "Another sentence", "Third one"]}
```

**Response:**
```json
{
  "embeddings": [[0.0011, -0.0146, 0.0203, ...]],
  "dims": 384,
  "model": "Xenova/bge-small-en-v1.5",
  "elapsed_ms": 52
}
```

### `GET /health`

Health check.

```json
{"status": "ready", "model": "Xenova/bge-small-en-v1.5"}
```

## Usage Examples

### cURL (Linux/Mac)
```bash
curl -X POST http://localhost:3000/embed \
  -H "Content-Type: application/json" \
  -d '{"text": "Hello world"}'
```

### PowerShell (Windows)
```powershell
Invoke-RestMethod -Uri http://localhost:3000/embed -Method Post -ContentType "application/json" -Body '{"text": "Hello world"}'
```

### JavaScript (fetch)
```javascript
const res = await fetch('http://localhost:3000/embed', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ text: ['Hello', 'World'] })
});
const { embeddings } = await res.json();
console.log(embeddings[0].length); // 384
```

### Python (requests)
```python
import requests
r = requests.post('http://localhost:3000/embed', json={"text": "Hello world"})
embedding = r.json()["embeddings"][0]  # 384-dim vector
```

## Configuration

Set via environment variables:

| Variable | Default | Description |
|----------|---------|-------------|
| `PORT` | `3000` | Server port |
| `MODEL` | `Xenova/bge-small-en-v1.5` | HuggingFace model ID |

```bash
# Use a different model
docker run -p 3000:3000 -e MODEL=Xenova/all-MiniLM-L6-v2 embeddings

# Different port
docker run -p 8080:8080 -e PORT=8080 embeddings
```

## Available Models

Any ONNX model from the [Xenova](https://huggingface.co/Xenova) collection works:

| Model | Dims | Size | Quality |
|-------|------|------|---------|
| `Xenova/bge-small-en-v1.5` | 384 | 32MB | ⭐ Best for English |
| `Xenova/all-MiniLM-L6-v2` | 384 | 22MB | Good, smallest |
| `Xenova/bge-base-en-v1.5` | 768 | 110MB | Higher quality |
| `Xenova/multilingual-e5-small` | 384 | 113MB | Multilingual |

## How It Works

The key challenge: `onnxruntime-node` (native ONNX runtime) requires glibc, but Alpine uses musl libc. The solution:

1. Install `@xenova/transformers` (which depends on `onnxruntime-node`)
2. **Stub** `onnxruntime-node` to re-export `onnxruntime-web` instead
3. `onnxruntime-web` uses **WASM** — runs on any OS/libc
4. Set `numThreads = 1` (WASM workers not needed in Node.js server)
5. Copy WASM binaries to where transformers.js expects them

This gives you the full transformer inference pipeline (tokenizer + model) running in pure WASM on Alpine.

## Project Structure

```
├── Dockerfile       # Alpine + Node 20, WASM stubbing
├── package.json     # @xenova/transformers + onnxruntime-web + express
├── server.js        # Express API with /embed and /health
├── preload.js       # (Optional) Pre-download model during build
└── .dockerignore    # Exclude node_modules from context
```

## Sharing

### Push to Docker Hub
```bash
docker tag embeddings yourusername/alpine-embeddings:latest
docker push yourusername/alpine-embeddings:latest
```

### Others can run it directly
```bash
docker pull yourusername/alpine-embeddings:latest
docker run -p 3000:3000 yourusername/alpine-embeddings:latest
```

### Share as code (this repo)
```bash
git clone https://huggingface.co/asusf15/alpine-embeddings
cd alpine-embeddings
docker build -t embeddings .
docker run -p 3000:3000 embeddings
```

## Docker Compose

```yaml
version: '3.8'
services:
  embeddings:
    build: .
    ports:
      - "3000:3000"
    environment:
      - MODEL=Xenova/bge-small-en-v1.5
    restart: unless-stopped
```

```bash
docker compose up -d
```

## Limits

- Max 128 texts per request
- Max 10MB request body
- Single-threaded WASM (~50-100ms per text)
- First request after cold start takes ~5s (model loading)

## License

MIT

<!-- ml-intern-provenance -->
## Generated by ML Intern

This model repository was generated by [ML Intern](https://github.com/huggingface/ml-intern), an agent for machine learning research and development on the Hugging Face Hub.

- Try ML Intern: https://smolagents-ml-intern.hf.space
- Source code: https://github.com/huggingface/ml-intern