# Backend Push Notifications


## Overview
This part of the backend handles device push notifications for registered users. It consumes messages from RabbitMQ, looks up user device tokens from a MySQL database, and sends notifications via Expo's API. Failed deliveries are retried or sent to a dead-letter queue.


## Requirements
- Python 3.12+
- MySQL database
- RabbitMQ
- Python packages from requirements.txt


## Configuration

**Environment variables:**

- `LOG_LEVEL` (DEBUG, INFO, WARNING, ERROR, CRITICAL)

- `RABBITMQ_URL`

- `MYSQL_HOST`, `MYSQL_USER`, `MYSQL_PASSWORD`, `MYSQL_DATABASE`

- `API_ENDPOINT` (Expo push API)


## Metrics

Metrics are exposed on port `9000` for Prometheus, including:

- `MSG_PUBLISHED`

- `MSG_FAILED`

- `MSG_RETRY`

- Queue sizes