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

# 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+)

go run main.go

The server starts on port 8080.

Docker

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

Docker Compose

docker compose up -d

The service restarts automatically unless explicitly stopped.

Docker Image

The image uses a two-stage build:

Builder — golang:1.25-alpine compiles a statically linked binary with debug info stripped (-ldflags="-w -s").
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

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