Update README and service configuration for Gunicorn usage and permissions

README.md

@@ -20,7 +20,7 @@ The repository contains a Flask-based API proxy that allows Omada controller to
 On an Ubuntu/Debian system, you can install the required packages using apt:
 
 ```bash
-sudo apt install -y python3 python3-dotenv python3-flask python3-flask-httpauth python3-requests
+sudo apt install -y python3 python3-dotenv python3-flask python3-flask-httpauth python3-requests gunicorn
 ```
 
 Copy the `app.py` file to your desired location, and run it using Python:
@@ -29,6 +29,12 @@ Copy the `app.py` file to your desired location, and run it using Python:
 flask run app.py
 ```
 
+or use Gunicorn for production:
+
+```bash
+gunicorn --bind 0.0.0.0:8080 app:app
+```
+
 ## Self-Signed SSL Certificate (Optional)
 
 To run the Flask app with HTTPS, you can create a self-signed SSL certificate:
@@ -42,3 +48,21 @@ Then run the Flask app with SSL context:
 ```bash
 flask run --cert=cert.pem --key=key.pem
 ```
+
+To use the Mail In A Box server's SSL certificate, use the following files:
+
+- certificate: `/miab-data/ssl/ssl_certificate.pem`
+- private key: `/miab-data/ssl/ssl_private_key.pem`
+
+> **Note:** You have to run the web server as root to access the private key file.
+
+## Service Installation
+
+```
+sudo mkdir -p /opt/dns-updater
+sudo cp app.py /opt/dns-updater/
+sudo cp dns-updater.service /etc/systemd/system/
+sudo systemctl daemon-reload
+sudo systemctl enable --now dns-updater.service
+sudo systemctl status dns-updater.service
+```