pulsemon

A service health checker built from scratch in Go. Give it a list of URLs, and it pings all of them every 30 seconds concurrently. If something goes down, you get a Telegram alert immediately.

Think baby Datadog. No frameworks, no external dependencies, just Go stdlib.

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What it does

• Reads a list of services from a JSON config file
• Pings every service simultaneously using goroutines
• Logs response time and status for every check
• Sends a Telegram alert the moment a service goes down
• Repeats every 30 seconds forever

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How it works

config.json (list of services)
      ↓
main.go fires one goroutine per service
      ↓
checker pings the URL, measures response time
      ↓
results collected through a buffered channel
      ↓
logger prints [UP] / [DOWN] with response time
      ↓
notifier sends Telegram alert for anything down
      ↓
waits 30 seconds, repeats

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Project structure

pulsemon/
├── config/
│   ├── config.go   → reads services from config.json
│   └── env.go      → loads .env file (zero dependencies)
├── checker/
│   └── checker.go  → pings one URL, returns result with response time
├── notifier/
│   └── notify.go   → sends Telegram alert when a service is down
├── logger/
│   └── logger.go   → formats and prints check results
└── main.go         → wires everything together

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Setup

1. Clone the repo

git clone https://github.com/SHAIK14/pulsemon
cd pulsemon

2. Create your config file

Edit config.json with the services you want to monitor:

{
  "services": [
    {"name": "google", "url": "https://google.com"},
    {"name": "github", "url": "https://github.com"},
    {"name": "your-api", "url": "https://your-api.com/health"}
  ]
}

3. Set up Telegram alerts

• Create a bot via @BotFather on Telegram
• Get your chat ID by messaging your bot and hitting https://api.telegram.org/bot{TOKEN}/getUpdates

Create a .env file in the project root:

TELEGRAM_TOKEN=your_bot_token
TELEGRAM_CHAT_ID=your_chat_id

4. Run it

go run .

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Sample output

[UP]   google        200  423ms
[UP]   github        200  141ms
[DOWN] your-api           no such host

And on your phone:

🚨 Down: your-api
URL: https://your-api.com/health
Error: no such host

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What I learned building this

• Goroutines and buffered channels for concurrent HTTP checks
• Why you pass loop variables as goroutine arguments (loop capture bug)
• http.Client with timeout — non-negotiable in production
• time.Ticker for scheduled recurring work
• Separating concerns across packages (config, checker, notifier, logger)
• Loading .env files without any external library
• HTTP POST to an external API (Telegram Bot API)