CoinGecko Price API

A lightweight REST API that collects cryptocurrency prices from CoinGecko and serves them from a PostgreSQL database. Built with Flask and Celery for reliable background data collection, fully containerized with Docker.

Features

• Automated Price Collection: Fetches prices every 30 seconds from CoinGecko API
• Cached Responses: Redis-backed caching reduces database load
• Rate Limiting: Protects the API with 1 request per second limit
• Connection Pooling: Efficient PostgreSQL connection management
• Docker Compose: One command to run the entire stack

Supported Cryptocurrencies

CoinGecko ID	Short Code
bitcoin	btc
ethereum	eth
zenon-2	znn
quasar-2	qsr

API Endpoints

GET /price

Returns the latest USD prices for all tracked cryptocurrencies.

Response:

{
  "data": {
    "btc": {
      "usd": 43250.00,
      "timestamp": "2024-01-05T12:30:45.123456Z"
    },
    "eth": {
      "usd": 2280.50,
      "timestamp": "2024-01-05T12:30:45.123456Z"
    },
    "znn": {
      "usd": 1.25,
      "timestamp": "2024-01-05T12:30:45.123456Z"
    },
    "qsr": {
      "usd": 0.15,
      "timestamp": "2024-01-05T12:30:45.123456Z"
    }
  }
}

Rate Limit Exceeded (429):

{
  "error": "Too Many Requests",
  "code": 429
}

Quick Start with Docker

# Clone and start
git clone https://github.com/0x3639/coingecko-api.git
cd coingecko-api
docker compose up -d

The API will be available at http://localhost:5000/price

Docker Services

Service	Description	Port
web	Flask API server	5000
worker	Celery task worker	-
beat	Celery scheduler	-
postgres	PostgreSQL 15	5432
redis	Redis 7	6379

Docker Commands

# Start all services
docker compose up -d

# View logs
docker compose logs -f

# Stop all services
docker compose down

# Stop and remove data volume
docker compose down -v

Local Development (without Docker)

Prerequisites

• Python 3.9+
• PostgreSQL
• Redis

Setup

1. Create and activate virtual environment

   python -m venv venv
   source venv/bin/activate

2. Install dependencies

   pip install -r requirements.txt

3. Configure environment

   cp .env.example .env
   # Edit .env with your database credentials

4. Start services

   # Terminal 1: Flask
   python app.py
   
   # Terminal 2: Celery worker
   celery -A celery_worker worker --loglevel=info
   
   # Terminal 3: Celery beat
   celery -A celery_worker beat --loglevel=info

Architecture

┌─────────────────┐     ┌─────────────────┐     ┌─────────────────┐
│   CoinGecko     │     │     Redis       │     │   PostgreSQL    │
│      API        │     │  (Cache/Broker) │     │    Database     │
└────────┬────────┘     └────────┬────────┘     └────────┬────────┘
         │                       │                       │
         ▼                       ▼                       ▼
┌─────────────────────────────────────────────────────────────────┐
│  Docker Compose                                                 │
│                                                                 │
│  ┌─────────────┐    ┌─────────────┐    ┌─────────────────────┐  │
│  │ Celery Beat │───▶│   Celery    │───▶│  fetch_data task    │  │
│  │ (Scheduler) │    │   Worker    │    │  (every 30 sec)     │  │
│  └─────────────┘    └─────────────┘    └─────────────────────┘  │
│                                                                 │
│  ┌─────────────────────────────────────────────────────────┐    │
│  │                    Flask App                            │    │
│  │  /price endpoint ──▶ Cache Check ──▶ PostgreSQL Query   │    │
│  └─────────────────────────────────────────────────────────┘    │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

Database Schema

The application automatically creates the required table:

CREATE TABLE coingecko (
    id SERIAL PRIMARY KEY,
    currency_id VARCHAR(255),
    currency_value REAL,
    timestamp TIMESTAMP(6) DEFAULT CURRENT_TIMESTAMP
)

Environment Variables

Variable	Default	Description
DB_HOST	localhost	PostgreSQL host
DB_PORT	5432	PostgreSQL port
DB_USER	coingecko	Database user
DB_PASSWORD	coingecko	Database password
DB_NAME	coingecko	Database name
REDIS_URL	redis://localhost:6379/0	Redis URL for caching
CELERY_BROKER_URL	redis://localhost:6379/1	Redis URL for Celery

License

MIT