Unified log levels

- Logger doesn't start with log level DEBUG by default, instead reads a environment variable
- Secret handler raises exceptions instead of using the module os to exit
- Added extensive debug logging
- Notifications: Added timestamp and category

README.md

@@ -1,4 +1,90 @@
-# docker-repository-query
+# Docker Repository Query Service
 
+A FastAPI-based service that monitors Docker repositories (Docker Hub and GitHub Container Registry) for new image versions and sends notifications when updates are detected.
 
-FastAPI service with endpoints that check for updated versions of two applications so far, Suwayomi and Pi-hole.
+## Features
+
+- **Multi-Registry Support**: Queries both Docker Hub and GitHub Container Registry (GHCR)
+- **Version Tracking**: Maintains local state of latest known versions in MySQL
+- **Automatic Notifications**: Sends alerts when new versions are detected
+- **Prometheus Metrics**: Built-in request monitoring
+- **Scheduled Queries**: Designed to be called by external schedulers (cron, Kubernetes CronJob, etc.)
+
+## Use Case
+
+This service is ideal for:
+- Monitoring self-hosted applications for updates
+- Automating update notifications for Docker-based infrastructure
+- Tracking specific image tags across different registries
+
+## Prerequisites
+
+- Python 3.8+
+- MySQL database
+- 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://0.0.0.0:5000`
+- **Metrics Server**: `http://0.0.0.0:9000`
+
+## API Endpoints
+
+### Health Check
+```
+GET /health
+```
+Returns 200 status code if the service is running.
+
+### Check Suwayomi Updates
+```
+GET /suwayomi
+```
+
+Queries GitHub Container Registry for the latest stable version of Suwayomi/Tachidesk.
+
+**Response:**
+- `200 OK`: New version detected and notification sent
+- `204 No Content`: No new version available
+- `500 Internal Server Error`: Query or database error
+
+**Registry:** GitHub Container Registry (ghcr.io)
+**Repository:** Suwayomi/tachidesk
+**Tag:** stable
+
+### Check Pi-hole Updates
+```
+GET /pihole
+```
+
+Queries Docker Hub for the latest version of Pi-hole.
+
+**Response:**
+- `200 OK`: New version detected and notification sent
+- `204 No Content`: No new version available
+- `500 Internal Server Error`: Query or database error
+
+**Registry:** Docker Hub
+**Repository:** pihole/pihole
+**Tag:** latest
+
+## Monitoring
+
+### Prometheus Metrics
+
+Prometheus metrics are exposed on port 9000 and include:
+- HTTP request counters by method, path, and status code
+- Success/failure rates for version checks
+
+Access metrics at: `http://0.0.0.0:9000/metrics`