⚖️Scaling Django⚖️

$ python3 -m venv env # create virtual environment
$ source env/bin/activate 
$ poetry install # make sure you have install poetry on your machine

$ mkdir scale && cd scale
$ python3 -m venv env # create virtual environment
$ source env/bin/activate
$ poetry init # poetry initialization and generates *.toml file
$ poetry add djangorestframework psycopg2-binary Faker 
django-redis gunicorn
$ djang-admin startproject config .
$ python manage.py startapp products
$ touch Dockerfile
$ touch docker-compose.yml

─── scale
    ├── config
    │ ├── **init**.py
    │ ├── asgi.py
    │ ├── settings
    │ │ ├── **init**.py
    │ │ ├──base.py
    │ │ ├──dev.py
    │ │ ├──prod.py
    │ ├── urls.py
    │ └── wsgi.py
    ├── manage.py
    └── products
    └── .env
    └── manage.py
    └── docker-compose.yml
    └── Dockerfile

FROM python:3.8.5-alpine

# prevents Python from generating .pyc files in the container
ENV PYTHONDONTWRITEBYTECODE 1
# Turns off buffering for easier container logging
ENV PYTHONUNBUFFERED 1

RUN \
    apk add --no-cache curl

# install psycopg2 dependencies
RUN apk update \
    && apk add postgresql-dev gcc python3-dev musl-dev


# Install poetry
RUN pip install -U pip \
    && curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poetry.py | python
ENV PATH="${PATH}:/root/.poetry/bin"


RUN mkdir /code
RUN mkdir /code/staticfiles
RUN mkdir /code/mediafiles

WORKDIR /code
COPY . /code

RUN poetry config virtualenvs.create false \
    && poetry install --no-interaction --no-ansi

version: "3.9"

services:
  scale:
    restart: always
    build: .
    command: python manage.py runserver 0.0.0.0
    volumes:
      - .:/code
    ports:
      - 8000:8000
    env_file:
      - ./.env
    depends_on:
      - db
  db:
    image: "postgres:11"
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    ports:
      - 54322:5432
    environment:
      - POSTGRES_USER=scale
      - POSTGRES_PASSWORD=scale
      - POSTGRES_DB=scale

volumes:
  postgres_data:

docker-compose up

$ docker container ls
CONTAINER ID   IMAGE         COMMAND                  CREATED          STATUS          PORTS                                         NAMES

78ac4d15bcd8   postgres:11   "docker-entrypoint.s…"   2 hours ago      Up 31 seconds   0.0.0.0:54322->5432/tcp, :::54322->5432/tcp   scale_db_1

$ docker exec -it 78ac4d15bcd8 bash
 :/#
 :/# psql --username=postgres
 psql (11.12 (Debian 11.12-1.pgdg90+1))
 Type "help" for help.

 postgres=# CREATE DATABASE scale;
 postgres=# CREATE USER scale WITH PASSWORD 'scale';
 postgres=# ALTER ROLE scale SET client_encoding TO 'utf8';
 postgres=# ALTER ROLE scale SET default_transaction_isolation TO 'read committed';
 postgres=# ALTER ROLE scale SET timezone TO 'UTC';
 postgres=# ALTER ROLE scale SUPERUSER;
 postgres=# GRANT ALL PRIVILEGES ON DATABASE scale TO scale;
 postgres=# \q

from config.settings import BASE_DIR

DATABASES = {
    "default": {
        "ENGINE": "django.db.backends.postgresql_psycopg2",
        "ATOMIC_REQUESTS": True,
        "NAME": "scale",
        "USER": "scale",
        "PASSWORD": "scale",
        "HOST": "db",
        "PORT": "5432",
    }
}

# REDIS CONFIG
CACHES = {
    "default": {
        "BACKEND": "django_redis.cache.RedisCache",
        "LOCATION": "redis://redis:6379/0",
        "OPTIONS": {"CLIENT_CLASS": "django_redis.client.DefaultClient"},
    }
}

STATIC_URL = '/static/'
STATIC_ROOT = BASE_DIR.parent / "staticfiles"  # for collect static

MEDIA_ROOT = BASE_DIR.parent / "media"
MEDIA_URL = "/media/"

version: "3.9"

services:
  scale:
    restart: always
    build: .
    command: gunicorn config.wsgi:application --bind 0.0.0.0:8000
    volumes:
      - .:/code
      - static_volume:/code/staticfiles
      - media_volume:/code/mediafiles
    expose:
      - 8000
    env_file:
      - ./.env
    depends_on:
      - db
      - redis
  db:
    image: "postgres:11"
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    ports:
      - 54322:5432
    environment:
      - POSTGRES_USER=scale
      - POSTGRES_PASSWORD=scale
      - POSTGRES_DB=scale
  redis:
    image: redis
    ports:
      - 63799:6379
    restart: on-failure

  nginx:
    build: ./nginx
    restart: always
    volumes:
      - static_volume:/code/staticfiles
      - media_volume:/code/mediafiles
    ports:
      - 2000:80
    depends_on:
      - scale

volumes:
  postgres_data:
  static_volume:
  media_volume:

FROM nginx:latest

RUN rm /etc/nginx/conf.d/default.conf
COPY nginx.conf /etc/nginx/conf.d

upstream core {
    server scale:8000;
}

server {

    listen 80;

    location / {
        proxy_pass http://core;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $host;
        proxy_redirect off;
        client_max_body_size 100M;
    }

     location /staticfiles/ {
        alias /code/staticfiles/;
    }
      location /mediafiles/ {
        alias /code/mediafiles/;
    }

}

docker-compose up --build

from django.db import models
from django.utils.translation import gettext_lazy as _


class Category(models.Model):
    name = models.CharField(_("Category Name"), max_length=255, unique=True)
    description = models.TextField(null=True)

    class Meta:
        ordering = ("name",)
        verbose_name = _("Category")
        verbose_name_plural = _("Categories")

    def __str__(self) -> str:
        return self.name


class Product(models.Model):
    name = models.CharField(_("Product Name"), max_length=255)
    category = models.ForeignKey(
        Category, on_delete=models.DO_NOTHING)

    description = models.TextField()
    price = models.DecimalField(decimal_places=2, max_digits=10)
    quantity = models.IntegerField(default=0)
    discount = models.DecimalField(decimal_places=2, max_digits=10)
    image = models.URLField(max_length=255)

    class Meta:
        ordering = ("id",)
        verbose_name = _("Product")
        verbose_name_plural = _("Products")

    def __str__(self):
        return self.name

── products
│── management
│ │── **init**.py
│ │── commands
│ │ │── **init**.py
│ │ │── category_seed.py
│ │ │── product_seed.py

from django.core.management import BaseCommand
from django.db import connections
from django.db.utils import OperationalError
from products.models import Category

from faker import Faker


class Command(BaseCommand):
    def handle(self, *args, **kwargs):
        faker = Faker()

        for _ in range(30):
            Category.objects.create(
                name=faker.name(),
                description=faker.text(200)
            )

from django.core.management import BaseCommand
from django.db import connections
from django.db.utils import OperationalError
from products.models import Category, Product
from random import randrange, randint

from faker import Faker


class Command(BaseCommand):
    def handle(self, *args, **kwargs):
        faker = Faker()

        for _ in range(5000):
            price = randrange(10, 100)
            quantity = randrange(1, 5)
            cat_id = randint(1, 30)
            category = Category.objects.get(id=cat)
            Product.objects.create(
                name=faker.name(),
                category=category,
                description=faker.text(200),
                price=price,
                discount=100,
                quantity=quantity,
                image=faker.image_url()
)

$ docker-compose exec scale sh
/code # python manage.py makemigrations
/code # python manage.py migrate
/code # python manage.py createsuperuser
/code # python manage.py collectstatic --no-input
/code # python manage.py category_seed
/code # python manage.py product_seed # takes while to create 5000 data

from rest_framework import serializers

from .models import Product, Category


class CategorySerializers(serializers.ModelSerializer):
    class Meta:
        model = Category
        fields = "__all__"


class CategoryRelatedField(serializers.StringRelatedField):
    def to_representation(self, value):
        return CategorySerializers(value).data

    def to_internal_value(self, data):
        return data


class ProductSerializers(serializers.ModelSerializer):

    class Meta:
        model = Product
        fields = "__all__"


class ReadProductSerializer(serializers.ModelSerializer):

    category = serializers.StringRelatedField(read_only=True)
    # category = CategoryRelatedField()
    # category = CategorySerializers()

    class Meta:
        model = Product
        fields = "__all__"

from products.models import Product
from rest_framework import (
    viewsets,
    status,
)

import time
from .serializers import ProductSerializers, ReadProductSerializer

from rest_framework.response import Response


class ProductViewSet(viewsets.ViewSet):

    def list(self, request):
        serializer = ReadProductSerializer(Category.objects.all(), many=True)
        return Response(serializer.data)

    def create(self, request):
        serializer = ProductSerializers(data=request.data)
        serializer.is_valid(raise_exception=True)
        serializer.save()
        return Response(
            serializer.data, status=status.HTTP_201_CREATED)

    def retrieve(self, request, pk=None,):
        products = Product.objects.get(id=pk)
        serializer = ReadProductSerializer(products)
        return Response(
            serializer.data
        )

    def update(self, request, pk=None):
        products = Product.objects.get(id=pk)
        serializer = ProductSerializers(
            instance=products, data=request.data, partial=True)
        serializer.is_valid(raise_exception=True)
        serializer.save()
        return Response(
            serializer.data, status=status.HTTP_202_ACCEPTED)

    def destroy(self, request, pk=None):
        products = Product.objects.get(id=pk)
        products.delete()
        return Response(
            status=status.HTTP_204_NO_CONTENT
        )

from django.urls import path

from .views import ProductViewSet

urlpatterns = [
    path("product", ProductViewSet.as_view(
        {"get": "list", "post": "create"})),
    path(
        "product/<str:pk>",
        ProductViewSet.as_view(
            {"get": "retrieve", "put": "update", "delete": "destroy"}),
    ),
]

from rest_framework.views import APIView
from products.models import Category, Product
from rest_framework import (
    viewsets,
    status,
)
from rest_framework.pagination import PageNumberPagination
import time
from .serializers import CategorySerializers, ProductSerializers, ReadProductSerializer

from rest_framework.response import Response

from django.core.cache import cache

class ProductListApiView(APIView):

    def get(self, request):
        paginator = PageNumberPagination()
        paginator.page_size = 10

        # get products from cache if exists
        products = cache.get('products_data')

        #  if products does not exists on cache create it
        if not products:
            products = list(Product.objects.select_related('category'))
            cache.set('products_data', products, timeout=60 * 60)

        # paginating cache products
        result = paginator.paginate_queryset(products, request)

        serializer = ReadProductSerializer(result, many=True)
        return paginator.get_paginated_response(serializer.data)


class ProductViewSet(viewsets.ViewSet):

    def create(self, request):
        serializer = ProductSerializers(data=request.data)
        serializer.is_valid(raise_exception=True)
        serializer.save()

        # get cache of products
        #  if exists
        #  delete cache
        for key in cache.keys('*'):
            if 'products_data' in key:
                cache.delete(key)
        cache.delete("products_data")

        return Response(
            serializer.data, status=status.HTTP_201_CREATED)

    def retrieve(self, request, pk=None,):
        products = Product.objects.get(id=pk)
        serializer = ReadProductSerializer(products)

        return Response(
            serializer.data
        )

    def update(self, request, pk=None):
        products = Product.objects.get(id=pk)
        serializer = ProductSerializers(
            instance=products, data=request.data, partial=True)
        serializer.is_valid(raise_exception=True)
        serializer.save()
        for key in cache.keys('*'):
            if 'products_data' in key:
                cache.delete(key)
        cache.delete("products_data")
        return Response(
            serializer.data, status=status.HTTP_202_ACCEPTED)

    def destroy(self, request, pk=None):
        products = Product.objects.get(id=pk)
        products.delete()
        for key in cache.keys('*'):
            if 'products_data' in key:
                cache.delete(key)
        cache.delete("products_data")
        return Response(
            status=status.HTTP_204_NO_CONTENT
        )

from django.urls import path

from .views import ProductListApiView, ProductViewSet

urlpatterns = [

    path('products', ProductListApiView.as_view()),

    path("product", ProductViewSet.as_view(
        {"post": "create"})),
    path(
        "product/<str:pk>",
        ProductViewSet.as_view(
            {"get": "retrieve", "put": "update", "delete": "destroy"}),
    ),
]