Code-Memo

Deploying with WSGI

1. Understanding WSGI

WSGI (Web Server Gateway Interface) is a specification that defines how web servers communicate with Python web applications. Django uses WSGI as its default interface. In production, Django applications should not be served using runserver but instead through a WSGI-compatible server like Gunicorn, uWSGI, or mod_wsgi with Apache.

---

2. Configuring wsgi.py

Django projects include a wsgi.py file inside the project directory. This file is used to serve the application through WSGI-compatible servers.

import os
from django.core.wsgi import get_wsgi_application

os.environ.setdefault("DJANGO_SETTINGS_MODULE", "myproject.settings")

application = get_wsgi_application()

• os.environ.setdefault("DJANGO_SETTINGS_MODULE", "myproject.settings"): Defines the settings module.
• get_wsgi_application(): Creates the WSGI application object.

---

3. Running Django with Gunicorn

Gunicorn (Green Unicorn) is a popular WSGI server for serving Django applications in production.

a) Installing Gunicorn

pip install gunicorn

b) Running Gunicorn

gunicorn myproject.wsgi:application --bind 0.0.0.0:8000

• myproject.wsgi:application: Points to the application object in wsgi.py.
• --bind 0.0.0.0:8000: Binds Gunicorn to all available IPs on port 8000.

c) Running Gunicorn with Multiple Workers

gunicorn myproject.wsgi:application --workers 4 --bind 0.0.0.0:8000

• --workers 4: Runs Gunicorn with 4 worker processes for handling multiple requests.

d) Running Gunicorn as a Daemon (Background Process)

gunicorn myproject.wsgi:application --daemon

• --daemon: Runs Gunicorn as a background process.

e) Running Gunicorn with a Configuration File

Instead of passing all options via the command line, a config file can be used:

# gunicorn_config.py
bind = "0.0.0.0:8000"
workers = 4
timeout = 120
loglevel = "info"

Run Gunicorn with:

gunicorn -c gunicorn_config.py myproject.wsgi:application

---

4. Using uWSGI

uWSGI is another WSGI server that can be used to serve Django applications.

a) Installing uWSGI

pip install uwsgi

b) Running Django with uWSGI

uwsgi --http :8000 --module myproject.wsgi

c) Running uWSGI with INI Configuration

Instead of passing options in the command, create a uwsgi.ini file:

[uwsgi]
module = myproject.wsgi
http = :8000
workers = 4
master = true
vacuum = true

Run uWSGI with:

uwsgi --ini uwsgi.ini

---

5. Serving Django with Apache and mod_wsgi

a) Installing mod_wsgi

For Apache, the mod_wsgi module must be installed.

pip install mod_wsgi

b) Generating Apache Configuration

mod_wsgi-express module-config

c) Configuring Apache

Add this to the Apache configuration file (/etc/httpd/conf/httpd.conf or /etc/apache2/apache2.conf):

<VirtualHost *:80>
    ServerName example.com
    DocumentRoot /path/to/myproject

    <Directory /path/to/myproject>
        Require all granted
    </Directory>

    WSGIDaemonProcess myproject python-home=/path/to/venv python-path=/path/to/myproject
    WSGIProcessGroup myproject
    WSGIScriptAlias / /path/to/myproject/myproject/wsgi.py
</VirtualHost>

Restart Apache:

sudo systemctl restart apache2  # Ubuntu
sudo systemctl restart httpd    # CentOS/Rocky Linux

---

6. Running Django with Nginx and Gunicorn

Nginx is a high-performance web server often used as a reverse proxy in front of Gunicorn.

a) Installing Nginx

sudo apt install nginx   # Ubuntu/Debian
sudo yum install nginx   # CentOS/Rocky Linux

b) Configuring Nginx

Edit /etc/nginx/sites-available/myproject (or /etc/nginx/conf.d/myproject.conf):

server {
    listen 80;
    server_name 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;
    }
}

Enable the site and restart Nginx:

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

---

7. Running Django as a Systemd Service

For automatic startup, create a systemd service file /etc/systemd/system/myproject.service:

[Unit]
Description=Gunicorn server for Django project
After=network.target

[Service]
User=www-data
Group=www-data
WorkingDirectory=/path/to/myproject
ExecStart=/path/to/venv/bin/gunicorn --workers 4 --bind 0.0.0.0:8000 myproject.wsgi:application
Restart=always

[Install]
WantedBy=multi-user.target

Enable and start the service:

sudo systemctl daemon-reload
sudo systemctl enable myproject
sudo systemctl start myproject

Check status:

sudo systemctl status myproject

---

8. Debugging WSGI Deployment Issues

a) Checking Gunicorn Logs

journalctl -u myproject --no-pager

b) Checking Nginx Logs

sudo tail -f /var/log/nginx/error.log

c) Testing Gunicorn Manually

gunicorn myproject.wsgi:application --bind 127.0.0.1:8000

d) Running wsgi.py Manually

python myproject/wsgi.py