How to Use Nginx with FastAPI for Production Deployment

To use nginx with FastAPI, run your FastAPI app with an ASGI server like uvicorn on a local port, then configure nginx as a reverse proxy to forward HTTP requests to that port. This setup improves performance, security, and allows handling static files and HTTPS easily.

Syntax

Here is the basic syntax to configure nginx as a reverse proxy for a FastAPI app running on localhost port 8000:

• server: Defines the server block for your domain or IP.
• listen: The port nginx listens on, usually 80 for HTTP.
• location /: Matches all requests and proxies them.
• proxy_pass: Forwards requests to the FastAPI app URL.
• proxy_set_header: Passes headers to preserve client info.

nginx

server {
    listen 80;
    server_name your_domain.com;

    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;
    }
}

Example

This example shows a complete FastAPI app running with uvicorn and an nginx config to serve it on port 80. It demonstrates how requests to http://your_domain.com/ reach the FastAPI app.

python + nginx

# fastapi_app.py
from fastapi import FastAPI

app = FastAPI()

@app.get("/")
async def read_root():
    return {"message": "Hello from FastAPI behind Nginx!"}

# Run the app with:
# uvicorn fastapi_app:app --host 127.0.0.1 --port 8000

# nginx config (e.g., /etc/nginx/sites-available/fastapi):
server {
    listen 80;
    server_name your_domain.com;

    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;
    }
}

# After saving nginx config, reload nginx with:
# sudo nginx -s reload

Output

When you visit http://your_domain.com/ in a browser, you will see JSON output: {"message": "Hello from FastAPI behind Nginx!"}

Common Pitfalls

Common mistakes when using nginx with FastAPI include:

• Not running the FastAPI app on the same host and port as nginx expects.
• Forgetting to set proxy_set_header directives, which can cause issues with client IP or HTTPS detection.
• Not reloading nginx after changing the config.
• Trying to serve static files through FastAPI instead of letting nginx handle them for better performance.

Example of a wrong and right nginx proxy config:

nginx

# Wrong: Missing proxy headers
server {
    listen 80;
    server_name your_domain.com;

    location / {
        proxy_pass http://127.0.0.1:8000;
    }
}

# Right: With proxy headers
server {
    listen 80;
    server_name your_domain.com;

    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;
    }
}

Quick Reference

Directive	Purpose
listen 80;	Listen on HTTP port 80
server_name your_domain.com;	Domain or IP address to serve
location / { ... }	Match all requests to proxy
proxy_pass http://127.0.0.1:8000;	Forward requests to FastAPI app
proxy_set_header Host $host;	Preserve original Host header
proxy_set_header X-Real-IP $remote_addr;	Pass client IP to app
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;	Chain client IPs through proxies
proxy_set_header X-Forwarded-Proto $scheme;	Pass HTTP or HTTPS scheme

Key Takeaways

Run FastAPI with uvicorn on a local port before proxying with nginx.

Configure nginx as a reverse proxy with proper proxy headers for client info.

Reload nginx after config changes to apply them.

Use nginx to serve static files for better performance, not FastAPI.

Test your setup by visiting your domain to see FastAPI responses through nginx.