wsgi_hosting - dwilson2547/wiki_demo GitHub Wiki

Absolutely, Daniel! Hosting a WSGI application involves several steps, from writing your app to deploying it on a server. Here’s a detailed, step-by-step guide to help you through the process:

• 1. Write Your WSGI Application
• 2. Choose a WSGI Server
• 3. Install the WSGI Server
• 4. Test Your Application Locally
• 5. Prepare for Production Deployment
  • A. Choose a Hosting Provider
  • B. Set Up Your Server
• 6. Deploy Your Application
  • A. Upload Your Code
  • B. Create a Virtual Environment
  • C. Install Gunicorn System-wide (Optional)
• 7. Run Your Application with a Process Manager
• 8. Set Up a Reverse Proxy (Nginx)
• 9. Secure Your App with SSL (HTTPS)
• 10. Monitor and Maintain
• Summary Table

First, ensure you have a WSGI-compliant application. Here’s a simple example using Flask (a popular WSGI framework):

# app.py
from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello():
    return "Hello, WSGI World!"

if __name__ == '__main__':
    app.run()

• This is a basic Flask app, but the same principles apply to Django, Pyramid, or even raw WSGI apps.

You need a WSGI server to run your application in production. Popular choices include:

• Gunicorn (recommended for beginners)
• uWSGI (highly configurable)
• Waitress (pure-Python, Windows-friendly)
• mod_wsgi (for Apache)

For this guide, we’ll use Gunicorn.

Install Gunicorn using pip:

pip install gunicorn

Run your app with Gunicorn to ensure it works:

gunicorn -w 4 -b 0.0.0.0:8000 app:app

• -w 4: Use 4 worker processes.
• -b 0.0.0.0:8000: Bind to all network interfaces on port 8000.
• app:app: The first app is the module name (app.py), and the second app is the Flask application object.

Visit http://localhost:8000 in your browser. You should see your app running.

You can host your WSGI app on:

• VPS (Virtual Private Server): DigitalOcean, Linode, AWS EC2, etc.
• Platform-as-a-Service (PaaS): Heroku, Render, PythonAnywhere.
• Shared Hosting: Some providers support WSGI (e.g., A2 Hosting).

For this guide, we’ll use a VPS (e.g., DigitalOcean).

1. Create a VPS instance and SSH into it.
2. Update the system:

   sudo apt update && sudo apt upgrade -y

3. Install Python, pip, and dependencies:

   sudo apt install python3 python3-pip python3-venv -y

Use git, scp, or rsync to upload your code to the server. For example:

scp -r /path/to/your/app user@your-server-ip:/path/to/deploy

python3 -m venv /path/to/venv
source /path/to/venv/bin/activate
pip install -r requirements.txt

sudo pip install gunicorn

Use a process manager like systemd or Supervisor to keep your app running. Here’s how to set up a systemd service:

1. Create a service file:

   sudo nano /etc/systemd/system/myapp.service

2. Add the following (adjust paths as needed):

   [Unit]
   Description=Gunicorn instance for my WSGI app
   After=network.target
   
   [Service]
   User=your-user
   Group=www-data
   WorkingDirectory=/path/to/your/app
   Environment="PATH=/path/to/venv/bin"
   ExecStart=/path/to/venv/bin/gunicorn -w 4 -b 0.0.0.0:8000 app:app
   
   [Install]
   WantedBy=multi-user.target

3. Enable and start the service:

   sudo systemctl daemon-reload
   sudo systemctl start myapp
   sudo systemctl enable myapp

A reverse proxy (like Nginx) handles static files, SSL, and forwards requests to your WSGI app.

1. Install Nginx:

   sudo apt install nginx -y

2. Configure Nginx:

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

   Add:

   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;
       }
   }

3. Enable the site:

   sudo ln -s /etc/nginx/sites-available/myapp /etc/nginx/sites-enabled
   sudo nginx -t
   sudo systemctl restart nginx

Use Let’s Encrypt to add SSL:

1. Install Certbot:

   sudo apt install certbot python3-certbot-nginx -y

2. Obtain a certificate:

   sudo certbot --nginx -d your-domain.com

• Logs: Check logs for errors:

  sudo journalctl -u myapp -f
  sudo tail -f /var/log/nginx/error.log

• Updates: Regularly update your server and dependencies.