FastAPI Deployment Guide for Internal LAN - Debian 12

This guide walks through deploying a Python 3.10.0 FastAPI application with SQLite on a Debian 12 server for internal LAN access.

Table of Contents

• Prerequisites
• System Setup
• Project Configuration
• Server Configuration
• Security
• Maintenance
• Troubleshooting

Prerequisites

Ensure you have:
- Debian 12 server with sudo access
- Python 3.10.0 FastAPI application
- SQLite database
- Internal LAN network

System Setup

First, update your system and install required packages:

# Update system packages
sudo apt update && sudo apt upgrade -y

# Install required packages
sudo apt install -y python3-pip python3-venv nginx supervisor sqlite3

Project Configuration

1. Set Up Project Directory

# Create project directory
sudo mkdir -p /opt/fastapi_app
sudo chown $(whoami):$(whoami) /opt/fastapi_app

# Create and activate virtual environment
cd /opt/fastapi_app
python3 -m venv venv
source venv/bin/activate

2. Install Dependencies

# Install Python packages
pip install fastapi uvicorn sqlalchemy databases[sqlite] python-multipart

# Install any additional project dependencies
# pip install -r requirements.txt

Server Configuration

1. Create SystemD Service

Create /etc/systemd/system/fastapi.service:

[Unit]
Description=FastAPI application
After=network.target

[Service]
User=www-data
Group=www-data
WorkingDirectory=/opt/fastapi_app
Environment="PATH=/opt/fastapi_app/venv/bin"
ExecStart=/opt/fastapi_app/venv/bin/uvicorn main:app --host 0.0.0.0 --port 8000

[Install]
WantedBy=multi-user.target

2. Configure Nginx

Create /etc/nginx/sites-available/fastapi:

server {
    listen 80;
    server_name _;  # Matches any server name

    location / {
        proxy_pass http://127.0.0.1:8000;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto $scheme;
    }
}

3. Enable Configuration

# Set up Nginx
sudo ln -s /etc/nginx/sites-available/fastapi /etc/nginx/sites-enabled/
sudo rm /etc/nginx/sites-enabled/default
sudo nginx -t
sudo systemctl restart nginx

# Enable and start FastAPI service
sudo systemctl enable fastapi
sudo systemctl start fastapi

Security

1. File Permissions

# Set ownership and permissions
sudo chown -R www-data:www-data /opt/fastapi_app
sudo chmod 600 /opt/fastapi_app/your_database.db

2. Firewall Configuration

# Install and configure UFW
sudo apt install -y ufw
sudo ufw allow from 192.168.0.0/16 to any port 80  # Adjust IP range
sudo ufw enable

Maintenance

Application Updates

cd /opt/fastapi_app
source venv/bin/activate

# Update application files
# git pull  # If using git

# Update dependencies if needed
pip install -r requirements.txt

# Restart service
sudo systemctl restart fastapi

Monitoring

# Check service status
sudo systemctl status fastapi

# View logs
sudo journalctl -u fastapi -f

Troubleshooting

Common Issues

1. Service Won’t Start

   # Check logs for errors
   sudo journalctl -u fastapi -n 50

2. Permission Issues

   # Verify ownership
   ls -la /opt/fastapi_app

   # Fix permissions if needed
   sudo chown -R www-data:www-data /opt/fastapi_app

3. Database Access Problems

   # Check database permissions
   ls -la /opt/fastapi_app/your_database.db

   # Fix if needed
   sudo chown www-data:www-data /opt/fastapi_app/your_database.db
   sudo chmod 600 /opt/fastapi_app/your_database.db

Need Help?

If you encounter issues:
1. Check the application logs
2. Verify all services are running
3. Confirm network/firewall settings
4. Ensure all file permissions are correct

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Note: This guide assumes a basic Debian 12 installation and may need adjustment based on your specific environment and security requirements.