Python Advanced To-Do API with Celery

A robust FastAPI application demonstrating advanced Python patterns, including background task processing with Celery, scheduled jobs, and a reverse proxy setup with Nginx.

🚀 Features

• FastAPI Backend: Complete REST API for managing To-Do items.
• Asynchronous Tasks: Background processing for emails and CSV exports using Celery.
• Scheduled Jobs: Automated daily summaries using Celery Beat.
• Monitoring: Real-time task monitoring with Flower.
• Infrastructure: Proxying via Nginx and containerization with Docker Compose.
• Persistence: SQLite database for tasks and Redis as a message broker.

🛠️ Tech Stack

• Linter/Formatter: Flake8, Autopep8
• Backend: FastAPI, Pydantic, SQLAlchemy
• Task Queue: Celery, Redis
• Reverse Proxy: Nginx
• Monitoring: Flower

📋 Prerequisites

• Docker and Docker Compose installed.

🚀 Setup & Installation

1. Clone the repository:

   git clone <repository-url>
   cd python-advanced

2. Start the containers:

   docker compose up -d --build

3. Populate initial data:

   ./populate_data.sh

🌐 Service Endpoints

• API: http://localhost:8080
• Interactive Docs (Swagger UI): http://localhost:8080/docs
• Flower (Celery Monitor): http://localhost:5555

⚡ Manual Actions

Queue Daily Summary Manually

To trigger the daily summary generation immediately without waiting for the schedule:

docker compose exec api celery -A celery_app.celery call generate_daily_summary

The result will be saved in the ./shared/daily_summary.json file.

Test CSV Export

Run the provided test script to trigger an export, poll for completion, and download the resulting CSV:

./test_export.sh

Check Flake8 Compliance

To verify code formatting:

./.venv/bin/flake8 .

📅 Dynamic Task Scheduling

The application uses sqlalchemy-celery-beat for a database-backed scheduler. This allows you to manage periodic tasks via the API without restarting services.

List all scheduled tasks

curl -X GET http://localhost:8080/scheduler/tasks

Create or Update a task

To change the interval of the daily summary or add a new task:

curl -X POST http://localhost:8080/scheduler/tasks \
     -H "Content-Type: application/json" \
     -d '{
       "name": "Generar resumen diario (cada minuto)", 
       "task": "generate_daily_summary", 
       "interval_seconds": 30, 
       "enabled": true
     }'

Delete a task

curl -X DELETE "http://localhost:8080/scheduler/tasks/Generar%20resumen%20diario%20(cada%20minuto)"

Note: Changes are picked up automatically by the Celery Beat container within seconds.

📂 Project Structure

• api/: FastAPI application code, models, and Celery task definitions.
• nginx/: Nginx configuration files.
• shared/: Local directory for files generated by background tasks (JSON summaries, CSV exports).
• docker-compose.yml: Full stack orchestration.
• .flake8: Linting configuration.