Deploying FastAPI to Production: The Complete VPS Guide

Why VPS Over Serverless?

I choose VPS deployment for most of my projects because I need persistent WebSocket connections, background tasks, and full control over the runtime. Serverless has cold starts and connection limits that don't work for real-time systems.

My Stack

Step 1: Application Structure

/home/deploy/
├── attendance-system/
│   ├── app/
│   ├── venv/
│   └── gunicorn.conf.py
├── commandflow/
│   ├── app/
│   ├── venv/
│   └── gunicorn.conf.py
└── snapfix-api/
    ├── app/
    ├── venv/
    └── gunicorn.conf.py

Each app gets its own virtualenv and Gunicorn config. No shared dependencies.

Step 2: Gunicorn Configuration

python
# gunicorn.conf.py
bind = 'unix:/tmp/attendance.sock'
workers = 4
worker_class = 'uvicorn.workers.UvicornWorker'
accesslog = '/var/log/attendance/access.log'
errorlog = '/var/log/attendance/error.log'

Step 3: Nginx Reverse Proxy

nginx
server {
    server_name attendance-pro.online;
    
    location / {
        proxy_pass http://unix:/tmp/attendance.sock;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
    }
    
    location /ws {
        proxy_pass http://unix:/tmp/attendance.sock;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection 'upgrade';
    }
}

The Gotchas

1. WebSocket Timeout

Nginx has a default 60-second timeout for WebSocket connections. For long-lived connections, you need proxy_read_timeout 3600;.

2. Worker Count

Don't set workers = 2 * cpu_count + 1 blindly. For WebSocket-heavy apps, fewer workers with more connections per worker is better.

3. SSL Certificate Renewal

Certbot's auto-renewal runs via cron, but if it fails silently, your site goes down. I set up monitoring with a simple health check script.

Key Takeaway

Production deployment is where most projects die. The gap between uvicorn --reload and a production server is massive. Invest time in understanding your deployment stack — it's as important as the application code.