nginx-fastapi

Steps to Run FastAPI on a VPS with a Domain

1. Deploy FastAPI on Your VPS

You need to set up your VPS to run your FastAPI application. To do this, you typically use a production server like Uvicorn or Gunicorn and a web server like Nginx as a reverse proxy.

Prerequisites:

• A VPS (e.g., DigitalOcean, AWS EC2, etc.)

• A domain name

• A FastAPI project

2. Install FastAPI and Uvicorn on VPS

Log into your VPS and install the required packages.

ssh root@YOUR_VPS_IP
sudo apt update
sudo apt install python3-pip python3-venv -y

Create a virtual environment and install FastAPI and Uvicorn:

mkdir fastapi_app
cd fastapi_app
python3 -m venv venv
source venv/bin/activate
pip install fastapi uvicorn

3. Create a FastAPI Application

Create a simple main.py file with your FastAPI code:

nano main.py

from fastapi import FastAPI

app = FastAPI()

@app.get("/")
def read_root():
    return {"message": "Hello, world!"}

4. Run FastAPI using Uvicorn

Test your FastAPI app by running Uvicorn:

uvicorn main:app --reload

This will start FastAPI on http://YOUR_VPS_IP:8000. You should now be able to access your application using your VPS IP.

5. Install Nginx and Configure a Reverse Proxy

Nginx will act as a reverse proxy to forward traffic from your domain to the FastAPI app.

1. Install Nginx:

sudo apt install nginx -y

2. Configure Nginx for Your FastAPI App:

sudo nano /etc/nginx/sites-available/fastapi

Add the following configuration, replacing example.com with your actual domain:

server {
    listen 80;
    server_name example.com www.example.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;
    }
}

• You can multiple port

server {
    listen 80;
    server_name custom.example.com;

    # Proxy all normal requests to port 8080
    location / {
        proxy_pass http://127.0.0.1:8080;
        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 requests to /v1/ to the service running on port 1337
    location /v1 {
        proxy_pass http://127.0.0.1:1337;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

3. Enable the Nginx Configuration:

sudo ln -s /etc/nginx/sites-available/fastapi /etc/nginx/sites-enabled/

4. Restart Nginx:

sudo systemctl restart nginx

6. Point Your Domain to Your VPS

You need to point your domain to your VPS IP address.

1. Go to your domain registrar (e.g., Namecheap, GoDaddy).

2. Edit the DNS settings to add an A record:

   • Host: @ (or www)

   • Points to: Your VPS IP address

3. Save the settings and wait for the DNS propagation (may take up to 24 hours).

7. Enable HTTPS with Let's Encrypt (Optional)

To secure your FastAPI app with HTTPS, you can use Let's Encrypt to obtain a free SSL certificate.

1. Install Certbot:

sudo apt install certbot python3-certbot-nginx -y

2. Obtain an SSL Certificate:

sudo certbot --nginx -d example.com -d www.example.com

3. Follow the prompts to complete the SSL setup.

4. Test the SSL certificate renewal:

sudo certbot renew --dry-run

8. Access FastAPI via Domain

Now, you can access your FastAPI app via your domain at:

• http://example.com (without HTTPS)

• https://example.com (with HTTPS, if SSL is set up)

Conclusion

With these steps, you'll have FastAPI running on your VPS with your domain, and optionally secured with HTTPS via Let's Encrypt. You can scale this setup by using Docker, Gunicorn with Uvicorn workers, and more advanced deployment techniques if necessary.

Solution: Increase Nginx Header Buffer Sizes

1. Edit the Nginx Configuration: You will need to modify your Nginx configuration file (/etc/nginx/nginx.conf or the specific configuration file for your site in /etc/nginx/sites-available/).

   Add the following directives to increase the buffer sizes:

   http {
       ...
   
       # Increase the buffer sizes for reading headers
       proxy_buffer_size 16k;
       proxy_buffers 4 32k;
       proxy_busy_buffers_size 64k;
       proxy_temp_file_write_size 64k;
   }

   If you are working with a specific server block (e.g., /etc/nginx/sites-available/fastapi), you can also add these directives inside the server or location block:

   server {
       listen 80;
       server_name your_domain_or_ip;
   
       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;
   
           # Increase the buffer sizes for this location
           proxy_buffer_size 16k;
           proxy_buffers 4 32k;
           proxy_busy_buffers_size 64k;
           proxy_temp_file_write_size 64k;
       }
   }

2. Save the Configuration.

3. Test the Nginx Configuration: Always check if the Nginx configuration is valid before restarting it.

   sudo nginx -t

   If the output says syntax is ok and test is successful, you can proceed.

4. Restart Nginx: Restart Nginx to apply the changes.

   sudo systemctl restart nginx

Additional Considerations:

• If the error persists, you can further increase the buffer sizes (e.g., increase proxy_buffer_size to 32k or adjust proxy_buffers accordingly).

• Ensure your FastAPI application is not sending excessively large headers, such as very large cookies, unnecessary data, or multiple headers that can be optimized.

By increasing the buffer size, Nginx should now be able to handle larger headers without throwing the "upstream sent too big header" error.