LLRP Discovery Service

A lightweight Go service for discovering LLRP-compatible RFID readers on a network.

Features

• Auto-Detection: Automatically discovers host network interfaces and subnets (no configuration needed!)
• CIDR Subnet Scanning: Scan entire network ranges using CIDR notation (e.g., 192.168.1.0/24)
• Parallel Probing: Concurrent network scanning with configurable limits
• LLRP Protocol: Validates LLRP connectivity on port 5084
• REST API: Simple HTTP API for triggering discovery and retrieving results
• Docker Support: Multi-platform Docker images (amd64, arm64)
• Lightweight: ~8-10MB Docker image using multi-stage builds

Quick Start

Docker

# Auto-detect host network (requires host networking)
docker run --network host \
  ghcr.io/trakrf/llrp-discovery:latest

# Or manually specify subnets
docker run --network host \
  -e SUBNETS="192.168.1.0/24,10.0.0.0/24" \
  ghcr.io/trakrf/llrp-discovery:latest

Docker Compose

services:
  llrp-discovery:
    image: ghcr.io/trakrf/llrp-discovery:latest
    network_mode: host
    environment:
      - SUBNETS=192.168.1.0/24,10.0.0.0/24
      - ASYNC_LIMIT=1000
      - TIMEOUT_SECONDS=5
      - SCAN_PORT=5084
      - HTTP_PORT=8080

Local Build

go build -o llrp-discovery
./llrp-discovery

API Endpoints

GET /discover

Triggers a network scan and returns discovered readers.

Query Parameters:

• subnets (optional): Comma-separated CIDR ranges. Defaults to env var SUBNETS

Example:

curl "http://localhost:8080/discover?subnets=192.168.1.0/24"

Response:

{
  "readers": [
    {
      "ip": "192.168.1.135",
      "hostname": "SpeedwayR-12-CC-E1",
      "port": 5084
    }
  ],
  "scanned": 254,
  "duration_ms": 1234
}

GET /health

Health check endpoint.

curl http://localhost:8080/health

Configuration

All configuration via environment variables:

Variable	Default	Description
SUBNETS	auto-detect	Comma-separated CIDR subnet list (auto-detects from host interfaces if not set)
ASYNC_LIMIT	1000	Maximum concurrent network probes
TIMEOUT_SECONDS	5	Timeout per IP probe (seconds)
SCAN_PORT	5084	LLRP port to scan
HTTP_PORT	8080	HTTP API port
MAX_DURATION_SECONDS	300	Maximum discovery duration (5 minutes)

Note: When SUBNETS is not set, the service automatically detects all non-loopback IPv4 network interfaces on the host and scans their subnets. This requires network_mode: host in Docker.

Use with TrakRF Keypr

Add to docker-compose.prod.yml:

services:
  llrp-discovery:
    image: ghcr.io/trakrf/llrp-discovery:latest
    network_mode: host
    restart: unless-stopped
    environment:
      - SUBNETS=192.168.1.0/24
      - HTTP_PORT=8082
    healthcheck:
      test: ["CMD", "wget", "--quiet", "--tries=1", "--spider", "http://localhost:8082/health"]
      interval: 30s
      timeout: 5s
      retries: 3

Then call from your application:

curl http://localhost:8082/discover

Attribution

This project's discovery algorithm is derived from the EdgeX Foundry device-rfid-llrp-go service, specifically from internal/driver/discover.go.

Original Copyright: Copyright 2020 Intel Corporation Original License: Apache License 2.0

License

Apache License 2.0 - see LICENSE file for details.

Copyright 2025 TrakRF