# Phone Letter Combinations HTTP Server

## Overview
This project is a simple HTTP server that provides letter combinations for a given phone number input. It is implemented using Python and Flask.

## Features
- Accepts a POST request with a phone number (digits 2-9)
- Returns all possible letter combinations based on standard phone mappings

## API Endpoint
### **POST /combinations**
**Request Body:**
```json
{
  "phoneNumber": "23"
}
```

**Response:**
```json
{
  "combinations": ["ad", "ae", "af", "bd", "be", "bf", "cd", "ce", "cf"]
}
```

## Installation & Usage

### 1. **Clone the Repository**
```bash
git clone https://github.com/MDN7-tech/phone-combinations.git
cd phone-combinations
```

### 2. **Build the Docker Image**
```bash
docker build -t phone-combinations .
```

### 3. **Run the Container**
```bash
docker run -p 8080:8080 --rm phone-combinations
```

### 4. **Test the API**
Use `curl` or Postman to test:
```bash
curl -X POST http://localhost:8080/combinations \
     -H "Content-Type: application/json" \
     -d '{"phoneNumber": "23"}'
```


## Security Considerations
- The application runs as a **non-root user** inside the container.
- The Dockerfile is optimized for security with minimal base image.
- Uses `gunicorn` instead of Flask’s built-in server for production.