# Speedtest Server

A lightweight HTTP server written in Go for measuring network bandwidth. Provides download and upload endpoints that clients can use to benchmark their connection speed.

## How It Works

- **Download test** — the server streams a requested number of bytes of random data to the client. The random pool (4 MB) is generated once at startup and cycled to fulfill any size request without disk I/O.
- **Upload test** — the client POSTs arbitrary data; the server reads and discards it, then responds with `200 OK`.

## Endpoints

| Method | Path | Description |
|--------|------|-------------|
| `GET` | `/download?bytes=<size>` | Stream `<size>` bytes of random data |
| `POST` | `/upload` | Consume uploaded data and acknowledge |

### Examples

```bash
# Download 100 MB and measure throughput
curl -o /dev/null -w "%{speed_download} bytes/s\n" \
  "http://localhost:8080/download?bytes=104857600"

# Upload 50 MB and measure throughput
curl -X POST -o /dev/null -w "%{speed_upload} bytes/s\n" \
  --data-binary @/dev/urandom \
  --limit-rate 50M \
  "http://localhost:8080/upload"
```

## Running

### Locally (requires Go 1.21+)

```bash
go run main.go
```

The server starts on **port 8080**.

### Docker

```bash
docker build -t speedtest-server .
docker run -p 8080:8080 speedtest-server
```

### Docker Compose

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

The service restarts automatically unless explicitly stopped.

## Docker Image

The image uses a two-stage build:

1. **Builder** — `golang:1.25-alpine` compiles a statically linked binary with debug info stripped (`-ldflags="-w -s"`).
2. **Runtime** — `gcr.io/distroless/static-debian12` — a minimal, shell-less base image. The binary runs as `nonroot:nonroot`.

## Configuration

| Parameter | Default | Description |
|-----------|---------|-------------|
| Port | `8080` | Hardcoded in `main.go` |
| Random pool size | `4 MB` | Pre-generated at startup |
| Upload read buffer | `32 KB` | Per-request buffer size |
