Website Monitor

A comprehensive website monitoring application built with ReasonML, OCaml, and server-reason-react. Monitor multiple websites for HTTP status deviations and receive alerts via email or webhooks.

Features

• Real-time Monitoring: Continuously monitor websites for HTTP 200 status deviations
• Alert System: Send alerts via email or webhooks when websites go down or recover
• Admin Dashboard: Beautiful, responsive web interface for managing websites and alerts
• REST API: Full CRUD API for programmatic access
• History Tracking: Keep detailed history of all website checks
• Docker Support: Fully containerized with Docker and Docker Compose
• Resource-Constrained Builds: Docker builds limited to 1 CPU core

Technology Stack

• Language: OCaml 5.0+ with ReasonML
• Web Framework: Dream (OCaml web framework)
• Frontend: server-reason-react (server-side React with ReasonML)
• Database: PostgreSQL with Caqti (OCaml database interface)
• Async: Lwt (OCaml's cooperative threading library)
• Container: Docker & Docker Compose

Quick Start

Prerequisites

• Docker 20.10+
• Docker Compose 2.0+

Installation

1. Clone the repository:

git clone <repository-url>
cd test3

2. Create environment file:

cp .env.example .env

3. Edit .env with your configuration (especially SMTP settings for alerts)

4. Start the application:

docker-compose up -d

5. Access the dashboard at http://localhost:8080

Configuration

Environment Variables

Variable	Description	Default
DB_PASSWORD	PostgreSQL database password	changeme
SMTP_HOST	SMTP server hostname	smtp.gmail.com
SMTP_PORT	SMTP server port	587
SMTP_USER	SMTP username	-
SMTP_PASSWORD	SMTP password	-
ADMIN_EMAIL	Email to receive all alerts	admin@example.com
SECRET_KEY	Secret key for sessions	-
ENVIRONMENT	Environment (development/production)	production

API Documentation

Websites

List all websites

GET /api/websites

Get website by ID

GET /api/websites/:id

Create website

POST /api/websites
Content-Type: application/json

{
  "name": "Example Site",
  "url": "https://example.com",
  "expected_status": 200,
  "timeout": 30,
  "check_interval": 300
}

Update website

PUT /api/websites/:id
Content-Type: application/json

{
  "name": "Updated Name",
  "active": true
}

Delete website

DELETE /api/websites/:id

Check website now

POST /api/websites/:id/check

Get website history

GET /api/websites/:id/history?limit=100

Get website status

GET /api/websites/:id/status

Alerts

List all alerts

GET /api/alerts

Get alert by ID

GET /api/alerts/:id

Create alert

POST /api/alerts
Content-Type: application/json

{
  "website_id": 1,
  "alert_type": "email",
  "config": {
    "to_email": "admin@example.com",
    "cc_email": "client@example.com",
    "subject_prefix": "[Monitor]"
  }
}

Update alert

PUT /api/alerts/:id
Content-Type: application/json

{
  "enabled": true
}

Delete alert

DELETE /api/alerts/:id

Stats

Get summary statistics

GET /api/stats/summary

Alert Types

Email Alerts

Configuration:

{
  "to_email": "recipient@example.com",
  "cc_email": "cc@example.com",  // optional
  "subject_prefix": "[Monitor]"    // optional
}

Webhook Alerts

Configuration:

{
  "url": "https://hooks.slack.com/services/...",
  "method": "POST",
  "headers": {
    "Content-Type": "application/json"
  },
  "body_template": ""
}

Development

Local Development

1. Install dependencies:

opam install . --deps-only

2. Build the project:

dune build

3. Run tests:

dune test

4. Run the application:

dune exec bin/main.exe

Docker Development

Build with CPU constraint (1 core):

docker build --build-arg BUILDKIT_INLINE_CACHE=1 -t website_monitor .

Run with Docker Compose:

docker-compose up

Project Structure

test3/
├── bin/
│   ├── dune              # Binary build configuration
│   └── main.ml           # Application entry point
├── lib/
│   ├── dune              # Library build configuration
│   ├── database.ml       # Database models and queries
│   ├── monitor.ml        # Website monitoring logic
│   ├── alert.ml          # Alerting system
│   ├── api.ml            # REST API handlers
│   ├── ui.ml             # Server-side React UI
│   └── scheduler.ml      # Background monitoring scheduler
├── docker/
│   └── Dockerfile
├── docker-compose.yml
├── dune-project
├── website_monitor.opam
├── .env.example
└── README.md

Monitoring Behavior

• Websites are checked at their configured check_interval (default: 5 minutes)
• Failed checks trigger alerts to configured endpoints
• Recovery alerts are sent when a website returns to normal
• Check history is retained for 30 days (configurable)
• The scheduler runs every minute to check due websites

CPU Constraints

The Docker build is configured to use only 1 CPU core:

ENV OPAMJOBS=1

In docker-compose.yml:

cpus: '1.0'
cpuset: '0'

Security Considerations

1. Environment Variables: Never commit .env files to version control
2. Secrets: Use strong random strings for SECRET_KEY
3. SMTP: Use app-specific passwords, not your main password
4. Database: Change default passwords in production
5. HTTPS: Use a reverse proxy (nginx, Traefik) for HTTPS

Troubleshooting

Database Connection Issues

docker-compose logs postgres

SMTP Issues

• Check SMTP credentials in .env
• Verify SMTP host and port
• Use app-specific passwords for Gmail

High CPU Usage

• Increase check_interval for less frequent checks
• Reduce number of active websites
• The build is already limited to 1 CPU core

License

MIT License - see LICENSE file for details

Contributing

1. Fork the repository
2. Create a feature branch
3. Make your changes
4. Write tests
5. Submit a pull request

Support

For issues and questions, please open an issue on the GitHub repository.