Matplotlib Graph Render API

A robust, containerized Flask API that allows you to execute Python code remotely to generate Matplotlib graphs. This service is designed for headless environments and includes authentication and basic logging.

Features

• Headless Rendering: Uses Matplotlib's Agg backend to render graphs without a display.
• Secure-ish Execution: Executes user-provided Python code in a restricted scope (see Security Note).
• Authentication: Protects endpoints with API Key authentication.
• Logging: Structured logging for monitoring and debugging.
• Dockerized: Ready for deployment using Docker.
• Tested: Comprehensive test suite using pytest.

Project Structure

.
├── src/
│   ├── app.py          # Main Flask application
│   ├── config.py       # Configuration management
│   └── executor.py     # Code execution logic
├── tests/              # Unit tests
├── Dockerfile          # Container definition
├── Makefile            # Convenience commands
└── requirements.txt    # Python dependencies

Getting Started

Prerequisites

• Python 3.10+
• Pip

Installation

1. Clone the repository:

   git clone https://github.com/your-username/matplotlib-render-api.git
   cd matplotlib-render-api

2. Install dependencies:

   make install
   # or
   pip install -r requirements.txt

3. Set up environment variables: Create a .env file in the root directory:

   PORT=5150
   API_KEY=your-secret-api-key
   DEBUG=True

Running Locally

make run
# or
export API_KEY=my-secret-key
python -m src.app

The server will start at http://0.0.0.0:5150.

API Documentation

1. Health Check

GET /

Returns a simple status message to verify the service is running.

• Response: 200 OK

2. Render Graph

POST /render-matplotlib

Executes the provided Python code and returns the generated graph as a PNG image.

• Headers:

  • Content-Type: application/json
  • X-API-Key: <your-api-key>

• Body:

  {
    "code": "import numpy as np\nimport matplotlib.pyplot as plt\nx = np.linspace(0, 10, 100)\nplt.plot(x, np.sin(x))\n"
  }

• Response:

  • 200 OK: Returns the PNG image (MIME type image/png).
  • 400 Bad Request: Missing code or invalid JSON.
  • 401 Unauthorized: Invalid or missing API Key.
  • 500 Internal Server Error: Error during code execution (returns error trace).

Docker

Build and run the container:

docker build -t matplotlib-api .
docker run -p 5150:5150 -e API_KEY=secret matplotlib-api

Testing

Run the test suite using pytest:

make test
# or
export PYTHONPATH=$PYTHONPATH:.
pytest

Security Note

⚠️ Warning: This application uses Python's exec() function to execute arbitrary code sent by the client. While basic sandboxing is attempted, it is not secure against malicious attacks.

• Do not expose this API publicly without strict firewalls and trusted clients.
• The current implementation allows imports to facilitate library usage, which increases risk.
• For a truly secure environment, consider running the execution logic inside an isolated ephemeral container (e.g., AWS Lambda, Firecracker microVMs).