A Brief Introduction to Django

Django is a high-level, open-source Python web framework that enables rapid development and clean, pragmatic design. It was designed to help developers take applications from concept to completion as quickly as possible. Django follows the Model-View-Controller (MVC) architectural pattern, which is leveraged for the development of complex, data-driven websites.

Django works by helping developers to write software that is divided into self-contained modules, which promotes reusability and pluggability of components, less code, low coupling, rapid development, and the principle of don’t repeat yourself (DRY). It includes an optional administrative create, read, update and delete interface that is generated dynamically through introspection and configured via admin models.

Django provides a plethora of features, including a lightweight and standalone web server for development and testing, a form serialization and validation system that can translate between HTML forms and values suitable for storage in the database, a template system that utilizes the concept of inheritance borrowed from object-oriented programming, a caching framework that can use any of several cache methods, support for middleware classes that can intervene at various stages of request processing and carry out custom functions, etc.

In a web system running on Django, data flows in a specific order. When a user makes a request, it first reaches the Django server. The server then checks the URL of the request against a list of URL patterns in the URLconf. Once a match is found, Django calls the given view, which processes the request and returns a response. The view retrieves data from the model, then loads a template, populating it with data. This template is then sent back to the user’s browser. If no match is found in the URLconf, Django invokes an error-handling view.

Quick Tutorial

Step 1: Install Django on your local machine

First, you need to install Django. You can do this with pip, Python’s package installer.

pip install django

Step 2: Create a new Django project

Next, you can create a new Django project with the following command:

django-admin startproject helloworld

Step 3: Create a new Django app

Navigate into your new project and create a new app:

cd helloworld
python manage.py startapp hello

Step 4: Create a view

In your new app directory (hello), open the file views.py and add the following code:

from django.http import HttpResponse

def hello_world(request):
    return HttpResponse("Hello, World!")

Step 5: Configure URL

In the hello directory, create a new file called urls.py and add the following code:

from django.urls import path

from . import views

urlpatterns = [
    path("", views.hello_world, name="hello_world"),
]

Then, include the hello app’s URLs in the project’s URL configuration. Open helloworld/urls.py and modify it as follows:

from django.contrib import admin
from django.urls import include, path

urlpatterns = [
    path("hello/", include("hello.urls")),
    path("admin/", admin.site.urls),
]

Step 6: Run the server

You can now run the server with the following command:

python manage.py runserver

You should be able to see your “Hello, World!” message at http://localhost:8000/hello.

Step 7: Deploying on GCP

1. Create a new VM instance on GCP and SSH into it.
2. Install Python, pip, and Django on the VM.
3. Install Gunicorn, a Python WSGI HTTP Server for UNIX.
4. Copy your Django project to the VM.
5. Run the Django project using Gunicorn.

gunicorn helloworld.wsgi

Step 8: Pointing a domain

1. Register a domain name from a registrar.
2. In the DNS settings of your domain, create an A record pointing to the external IP address of your GCP VM.

Step 9: Configuring security

1. Configure your firewall rules in the GCP console to only allow traffic on necessary ports (e.g., 80, 443 for HTTPS).
2. Install and configure a SSL certificate for HTTPS connections. You can use Let’s Encrypt to get a free SSL certificate.

Step 10: Dependency Management

1. Create a requirements.txt file in your Django project with all the necessary packages.
2. Use pip to install these packages on the VM.

pip install -r requirements.txt

Please note that this is a very basic tutorial and might not cover all aspects of a production-ready deployment, such as static files handling, database configuration, etc. Always refer to the official Django deployment checklist when moving to a production environment.