The entire process of deploying Flask applications using Nginx in Windows Server environment

1. Environmental preparation

1. operating system: Windows Server 2016/2019/2022
2. Python: Install the latest stable version (such as Python 3.10+), make sure to check itAdd Python to PATH。
3. Nginx for Windows: fromOfficial websiteDownload the Windows version (such as nginx/Windows-1.25.3).
4. Dependency tools: Git (optional, used for code pull), text editor (such as VS Code).

2. Create a Flask app

2.1 Project Structure

C:\flask-app\
   ├──           # Flask main program   ├── 
   ├── static\         # Static files   └── venv\           # Python Virtual Environment

2.2 Example

from flask import Flask

app = Flask(__name__)

@('/')
def home():
    return "Hello, World! Flask on Windows Server with Nginx!"

if __name__ == '__main__':
    (host='0.0.0.0', port=5000)

2.3 Installation dependencies

# Create a virtual environmentpython -m venv venv
venv\Scripts\activate

# Install Flask and Waitress (production-grade WSGI server)pip install flask waitress

3. Start Flask using Waitress

3.1 Start command

waitress-serve --port=5000 --threads=4 app:app

• Parameter description:
  • --port: Listen to the port
  • --threads: Number of threads (adjusted according to CPU core)

3.2 Create a startup script start_server.bat

@echo off
call venv\Scripts\activate
waitress-serve --port=5000 --threads=4 app:app

4. Configure Nginx reverse proxy

4.1 Modify the Nginx configuration file

worker_processes  1;

events {
    worker_connections  1024;
}

http {
    include       ;
    default_type  application/octet-stream;

    # Reverse proxy configuration    upstream flask_app {
        server 127.0.0.1:5000;  # Waitress Listening Address    }

    server {
        listen       80;
        server_name  your_domain.com;  # Replace with domain name or server IP
        # Static file processing (directly proxyed by Nginx)        location /static {
            alias C:/flask-app/static;  # Replace with the actual path            expires 30d;
        }

        # Dynamic request proxy to Flask        location / {
            proxy_pass http://flask_app;
            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;
        }
    }
}

4.2 Start Nginx

# Check configuration syntaxnginx -t

# Start Nginxstart nginx

# Restart (after modifying the configuration)nginx -s reload

5. Configure Windows Services (Self-Start on)

5.1 Using NSSM Tools (recommended)

• download
• Register for Nginx Services:

nssm install Nginx "C:\nginx\"  # Replace with Nginx actual pathnssm start Nginx

• Sign up for Waitress Services:

nssm install FlaskApp "C:\flask-app\venv\Scripts\" "C:\flask-app\venv\Scripts\" --port=5000 app:app
nssm start FlaskApp

6. FAQs and Solutions

6.1 Port conflict

• mistake: bind() to 0.0.0.0:5000 failed: Only one socket address is allowed
• solve: Check whether other programs occupy ports and usenetstat -ano | findstr :5000and terminate the process.

6.2 Static File 404

• mistake: The browser cannot load/static/
• solve: Ensure that the Nginx configuration is inaliasThe path uses forward slashes (C:/flask-app/static), and the directory exists.

6.3 Nginx 502 Bad Gateway

• reason: Nginx cannot connect to the backend Flask service.
• Troubleshooting:
  1. Check if Waitress is running (tasklist | findstr waitress)。
  2. Check whether the firewall allows port 5000.

7. Extend knowledge

7.1 Enable HTTPS

1. Use Let’s Encrypt to get a free certificate (domain name required).
2. Modify Nginx configuration:

server {
    listen 443 ssl;
    ssl_certificate     C:/ssl/your_domain.crt;
    ssl_certificate_key C:/ssl/your_domain.key;
    # ...Other configurations}

7.2 Load balancing

upstream flask_app {
    server 127.0.0.1:5000;
    server 127.0.0.1:5001;  # Start the second instance    least_conn;  # Use the least connection algorithm}

8. Things to note

1. Debug mode is disabled in production environment: Make sure Flask's(debug=False)。
2. Log Management: Configure the log paths of Nginx and Flask and archive them regularly.
3. Backup configuration: Backup before modifying key files (such as）。

Through the above steps, the Flask application will run in a high-reliability manner on Windows Server, and efficient reverse proxy and static resource acceleration will be achieved through Nginx.

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