Health Checker

한국어 | English

A Go-based health checker that periodically monitors website availability and sends notifications via Slack or Discord when issues are detected.

Features

• Periodic website health checks
• HTTP status code and response time monitoring
• Slack Webhook notification support
• Discord Webhook notification support
• Support for using both Slack and Discord simultaneously
• Test mode support (sends notifications even when status is healthy)

Installation

With Go installed

go install github.com/your-username/health-checker@latest

Or build from source:

git clone https://github.com/your-username/health-checker.git
cd health-checker
go build

Deployment

For deploying to external servers, see the Deployment Guide.

• Deploy using Docker
• Deploy directly to Linux servers
• Run as a systemd service

Usage

Basic Usage

# Windows PowerShell
.\health-checker.exe run --url https://example.com

# Linux/Mac
./health-checker run --url https://example.com

Command Options

Required Options

• --url, -u: URL to check (required)

  --url https://example.com

Optional Options

• --interval, -i: Check interval (default: 60s)

  --interval 30s    # Check every 30 seconds
  --interval 5m     # Check every 5 minutes

• --timeout, -t: Request timeout (default: 5s)

  --timeout 10s     # 10 second timeout

• --slack-webhook, -s: Slack Webhook URL

  --slack-webhook https://hooks.slack.com/services/YOUR/WEBHOOK/URL

• --discord-webhook, -d: Discord Webhook URL

  --discord-webhook https://discord.com/api/webhooks/YOUR/WEBHOOK/URL

• --latency-threshold: Response latency threshold (if specified, responses exceeding this are considered failures)

  --latency-threshold 3s     # Alert if response takes 3 seconds or more
  --latency-threshold 500ms  # Alert if response takes 500ms or more

• --test: Test mode (sends notifications even when status is healthy)

  --test

All duration-related options (--interval, --timeout, --latency-threshold and related environment variables) follow Go's time.ParseDuration format and support the following units:

• ns (nanoseconds), us/µs (microseconds), ms (milliseconds)
• s (seconds), m (minutes), h (hours)

Examples: 500ms, 2s, 1.5s, 3m, 1h30m

Environment Variables

You can use environment variables instead of flags:

• SLACK_WEBHOOK_URL: Slack Webhook URL
• DISCORD_WEBHOOK_URL: Discord Webhook URL
• LATENCY_THRESHOLD: Response latency threshold (e.g., 3s, 500ms)

# Windows PowerShell
$env:SLACK_WEBHOOK_URL="https://hooks.slack.com/services/YOUR/WEBHOOK/URL"
$env:DISCORD_WEBHOOK_URL="https://discord.com/api/webhooks/YOUR/WEBHOOK/URL"
$env:LATENCY_THRESHOLD="3s"
.\health-checker.exe run --url https://example.com

# Linux/Mac
export SLACK_WEBHOOK_URL="https://hooks.slack.com/services/YOUR/WEBHOOK/URL"
export DISCORD_WEBHOOK_URL="https://discord.com/api/webhooks/YOUR/WEBHOOK/URL"
export LATENCY_THRESHOLD="3s"
./health-checker run --url https://example.com

Examples

1. Basic Health Check (No Notifications)

.\health-checker.exe run --url https://example.com --interval 60s

2. Slack Notifications Only

.\health-checker.exe run \
  --url https://example.com \
  --interval 30s \
  --slack-webhook https://hooks.slack.com/services/YOUR/WEBHOOK/URL

3. Discord Notifications Only

.\health-checker.exe run \
  --url https://example.com \
  --interval 30s \
  --discord-webhook https://discord.com/api/webhooks/YOUR/WEBHOOK/URL

4. Using Both Slack and Discord

.\health-checker.exe run \
  --url https://example.com \
  --interval 60s \
  --slack-webhook https://hooks.slack.com/services/YOUR/WEBHOOK/URL \
  --discord-webhook https://discord.com/api/webhooks/YOUR/WEBHOOK/URL

5. Test Mode (Notifications Even When Healthy)

.\health-checker.exe run \
  --url https://example.com \
  --discord-webhook https://discord.com/api/webhooks/YOUR/WEBHOOK/URL \
  --test

6. Fast Monitoring with Short Intervals

.\health-checker.exe run \
  --url https://example.com \
  --interval 10s \
  --timeout 3s \
  --latency-threshold 2s \
  --discord-webhook https://discord.com/api/webhooks/YOUR/WEBHOOK/URL

Notification Conditions

Normal Mode (Default)

Notifications are sent in the following cases:

• HTTP request failure (connection errors, timeouts, etc.)
• HTTP status code is not 200 (500, 404, 503, etc.)
• (Optional) When --latency-threshold or LATENCY_THRESHOLD is set, if response time exceeds the threshold

Test Mode (--test flag)

Notifications are sent in all states:

• On error: Failure notification
• Non-200 status code: Failure notification
• 200 OK: Healthy notification (only in test mode)

Notification Message Format

Failure Notification

🚨 Site Failure Detected: https://example.com
Status Code: 500
Response Time: 2.5s

Or

🚨 Site Failure Detected: https://example.com
Error: connection timeout
Response Time: 5s

Healthy Notification (Test Mode)

✅ Site Healthy: https://example.com
Status Code: 200
Response Time: 150ms

Webhook Setup

Slack Webhook Setup

1. Create a new app at Slack API
2. Enable Incoming Webhooks
3. Copy the Webhook URL
4. Set it in the --slack-webhook flag or SLACK_WEBHOOK_URL environment variable

Discord Webhook Setup

1. Discord channel settings → Integrations → Webhooks
2. Create a new webhook
3. Copy the webhook URL
4. Set it in the --discord-webhook flag or DISCORD_WEBHOOK_URL environment variable

Stopping the Program

Press Ctrl+C to stop the program.

Press Ctrl+C to stop
^C
Shutting down...

Project Structure

health-checker/
├── cmd/
│   ├── root.go      # Root command
│   └── run.go       # Run subcommand
├── internal/
│   ├── checker/     # Health check logic
│   │   └── checker.go
│   └── notifier/    # Notification logic
│       ├── slack.go
│       ├── discord.go
│       └── notifier.go
├── main.go
├── go.mod
└── README.md

Tech Stack

• Language: Go
• CLI Framework: Cobra
• HTTP Client: net/http (standard library)

License

MIT License

Contributing

Issues and Pull Requests are welcome!