Updated readme

README.md

@@ -1,3 +1,97 @@
-# backend-api-internal
+# Internal Notifier API
 
-The internal part of the API. Duh!
+A FastAPI-based internal service that receives notification requests and forwards them to RabbitMQ for asynchronous processing and delivery to end users.
+
+## Features
+
+- **RabbitMQ Integration**: Asynchronous message queuing for reliable notification delivery
+- **Internal API Key Authentication**: Secure service-to-service communication
+- **MySQL Connection Pooling**: Database connection management with automatic health checks
+- **Prometheus Metrics**: Built-in request monitoring and tracking
+
+## Architecture
+
+This service acts as a gateway between internal services and the notification delivery system:
+
+```
+Internal Services → Internal Notifier API → RabbitMQ → Notification Workers → End Users
+```
+
+## Prerequisites
+
+- Python 3.8+
+- MySQL database
+- RabbitMQ server
+- Required Python packages (see Installation)
+
+## Installation
+
+```bash
+pip install -r requirements.txt
+```
+
+## Running the Application
+
+```bash
+python main.py
+```
+
+This starts two servers:
+- **Main API**: `http://0.0.0.0:8101`
+- **Metrics Server**: `http://0.0.0.0:9000`
+
+## API Endpoints
+
+### Receive Notifications
+```
+POST /internal/receive-notifications
+```
+
+Receives notification data from internal services and queues it to RabbitMQ for delivery.
+
+**Headers:**
+- `X-API-Key-Internal`: Your internal API key
+
+**Request Body:**
+```json
+{
+    "receipent_user_id": 12345,
+    "message": {
+        "title": "New Message",
+        "body": "You have a new notification",
+        "data": {
+            "category": "utility",
+            "link": "https://example.com",
+            "timestamp": "1760734800"
+        }
+    }
+}
+```
+
+- `category` - Optional.
+- `link` - Optional.
+- `timestamp` - Optional.
+
+**Response:**
+```json
+{
+    "status": "queued"
+}
+```
+
+**Success:** Returns 200 status code when message is successfully queued to RabbitMQ
+
+## Error Responses
+
+- `403 Forbidden`: Invalid, missing, or inactive API key
+- `500 Internal Server Error`: Database, RabbitMQ, or server error
+
+## Monitoring
+
+### Prometheus Metrics
+
+Prometheus metrics are exposed on port 9000 and include:
+- HTTP request counters by method, path, and status code
+- Custom metrics from the metrics server
+
+Access metrics at: `http://0.0.0.0:9000/metrics`