GoServiceMonitor

A lightweight HTTP health monitoring service written in Go — zero external dependencies, production-ready concurrency, and a clean REST API for managing and tracking the uptime of multiple web services.

Features

• Automated health checks — background goroutine polls every registered service every 30 seconds
• Concurrent checks — all services checked in parallel via goroutines and a buffered channel
• Uptime reporting — per-service uptime percentage and average response time calculated from up to 100 stored results
• Thread-safe — sync.Mutex guards shared service registry and history
• Graceful shutdown — handles SIGINT/SIGTERM with a 15-second drain window
• Structured logging — JSON logs via log/slog to stdout
• Zero dependencies — standard library only (net/http, encoding/json, log/slog, sync, context)

API Endpoints

Method	Path	Description
GET	/health	Liveness probe — returns {"status":"ok","time":"..."}
GET	/services	List all registered services
POST	/services	Register a new service {"name":"...","url":"..."}
GET	/services/{name}/check	Immediately check a single service
GET	/check-all	Concurrently check all services and return results
GET	/report	Uptime statistics for all services

Live Demo

The service is deployed on an AWS EC2 instance, running as a systemd service behind nginx on port 80.

Base URL: http://18.188.213.92

Note: The instance will terminate when I run out of AWS credits — if the URL is unreachable, that's likely why.

Try it:

curl http://18.188.213.92/health
curl http://18.188.213.92/report

Getting Started

Prerequisites: Go 1.21+

Linux

# Clone the repo
git clone https://github.com/<your-username>/GoServiceMonitor.git
cd GoServiceMonitor

# Build
go build -o service-monitor .

# Run (default port 8080)
./service-monitor

# Custom port
PORT=9000 ./service-monitor

Windows

go build -o service-monitor.exe .
.\service-monitor.exe

# Custom port
$env:PORT=9000; .\service-monitor.exe

Usage Example

# Register services to monitor
curl -X POST http://localhost:8080/services \
  -H "Content-Type: application/json" \
  -d '{"name":"github","url":"https://github.com"}'

# For Windows cmd:
curl -X POST http://localhost:8080/services -H "Content-Type: application/json" -d "{\"name\":\"google\",\"url\":\"https://www.google.com\"}"

# For Windows PowerShell:
Invoke-RestMethod -Uri "http://localhost:8080/services" -Method Post -ContentType "application/json" -Body '{"name":"google","url":"https://www.google.com"}'

# Run an immediate check on all services
curl http://localhost:8080/check-all

# View uptime report
curl http://localhost:8080/report

Sample report response

[
  {
    "name": "github",
    "url": "https://github.com",
    "uptime_percent": 100.0,
    "avg_response_ms": 142,
    "total_checks": 12,
    "last_checked": "2026-06-07T14:03:00Z"
  }
]

Health Check Logic

• Healthy: HTTP 2xx or 3xx response within 5 seconds
• Unhealthy: HTTP 4xx/5xx, timeout, or connection error
• History: Last 100 results stored per service

Configuration

Variable	Default	Description
PORT	8080	HTTP server port

Project Structure

GoServiceMonitor/
└── main.go     # Entire application — ~310 lines, stdlib only

License

MIT