manage.py

#!/usr/bin/env python
"""Django's command-line utility for administrative tasks."""
import os
import sys

from django.core.management.commands.runserver import Command as runserver

# Default port (e.g., 8000)
DEFAULT_PORT = 8000

# Read PORT from environment variable, fallback to DEFAULT_PORT
PORT = int(os.getenv('DJANGO_PORT', DEFAULT_PORT))

runserver.default_port = PORT
runserver.default_addr = '0.0.0.0'


def main():
    """Run administrative tasks."""
    os.environ.setdefault('DJANGO_SETTINGS_MODULE',
                          'todo_list_custom_backend.settings')
    try:
        from django.core.management import execute_from_command_line
    except ImportError as exc:
        raise ImportError(
            "Couldn't import Django. Are you sure it's installed and "
            "available on your PYTHONPATH environment variable? Did you "
            "forget to activate a virtual environment?"
        ) from exc
    execute_from_command_line(sys.argv)


if __name__ == '__main__':
    main()