Python

This documentation provides a step-by-step guide to setting up a Python Django server and creating a Dockerfile to deploy it via LocalOps.

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Prerequisites

To follow this tutorial, you will need the following:

• Python - v3.12.4 at the time of writing this doc.
• pip as a package manager for installing and maintaining dependencies. This usually comes bundled with Python > v3.4.
• Django - v5.0.7 at the time of writing this doc.
• [Docker] to build standalone containers to serve your Python app.

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Example Python Django App

In this tutorial we can go over a simple todo app that was created using Python Django.

Source Code: https://github.com/localopsco/django-todo-example

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Create Django Python app

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Use python venv (Virtual Environment)

python3 -m venv ~/.virtualenvs/djangodev

source ~/.virtualenvs/djangodev/bin/activate

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Install Django using pip

pip install Django

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Start a Django project

django-admin startproject django_todo

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Start a Django app in the project

python manage.py startapp todo

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Connect to your DB

In the tutorial example we will be connecting to Postgres DB.

Update your project settings.py file to refer the database details from environment variables.

DATABASES = {
  'default': {
    'ENGINE': 'django.db.backends.postgresql',
    'NAME': os.environ.get('DB_NAME'),
    'USER': os.environ.get('DB_USER'),
    'PASSWORD': os.environ.get('DB_PASS'),
    'HOST': os.environ.get('DB_HOST'),
    'PORT': os.environ.get('DB_PORT'),
  }
}

Make sure you have already created the provided database with username and password.

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Create DB models

• Update the todo/models.py file with below content,

from django.db import models
import uuid

class Task(models.Model):
    id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
    title = models.CharField(max_length=255)
    description = models.TextField()
    is_completed = models.BooleanField(default=False)
    attachment_url = models.URLField(null=True, blank=True)
    created_at = models.DateTimeField(auto_now_add=True)

    def __str__(self):
        return self.title

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Apply migrations

python manage.py migrate

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Add API endpoints

In this tutorial we will be adding REST CRUD (Create, Read, Update and Delete) endpoints for Task model using Django REST Framework.

Copy paste the below contents to your respective files,

from rest_framework import viewsets
from .models import Task
from .serializers import TaskSerializer

class TaskViewSet(viewsets.ModelViewSet):
    queryset = Task.objects.all()
    serializer_class = TaskSerializer

    def create(self, request, *args, **kwargs):
        return super().create(request, *args, **kwargs)

    def update(self, request, *args, **kwargs):
        return super().update(request, *args, **kwargs)

    def retrieve(self, request, *args, **kwargs):
        return super().retrieve(request, *args, **kwargs)

    def list(self, request, *args, **kwargs):
        return super().list(request, *args, **kwargs)

    def destroy(self, request, *args, **kwargs):
        return super().destroy(request, *args, **kwargs)

from django.urls import path, include
from rest_framework.routers import DefaultRouter
from .views import TaskViewSet

router = DefaultRouter()
router.register(r'tasks', TaskViewSet, basename='task')

urlpatterns = [
    path('', include(router.urls)),
]

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

urlpatterns = [
    path('admin/', admin.site.urls),
    path('api/v1/', include('todo.urls')),
]

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Run server

Export the required environment variables,

export DB_NAME=djangotodo \
  DB_USER=localops \
  DB_PASS=localops \
  DB_HOST=localhost \
  DB_PORT=5432

Run Django server,

python ./manage.py runserver

Visit http://localhost:8000/api/v1/tasks/ to see the list of tasks served from our Django app.

Voila! You have successfully created and run Django Python server with REST CRUD endpoints for Task model. 🎉

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Dockerize

Dockerizing makes the app run anywhere, agnostic of the platform. As long as Docker is installed, whether it’s Windows, Mac, or Linux, it can run with the same behavior.

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Create .dockerignore

Before creating the dockerfile, let’s create a .dockerignore file and add that contents that should not be copied over to the docker file system.

__pycache__/
Dockerfile
.dockerignore
README.md
.git

Read more about .dockerignore here

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Run DB migration inside docker image

In this tutorial, to keep DB migration step simple, we will create a entrypoint.sh script to run DB migrations each time the docker image is run.

#!/bin/bash
set -e

# Apply migrations
python manage.py migrate

# Start the Django application
exec "$@"

Optionally you can have a seperate image to run your DB migrations. In production setup, it is advisable to have seperate image to run DB migrations.

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Create Dockerfile

Now, Create a Dockerfile. The Dockerfile is a text file that contains the instructions for Docker to build the image.

The Dockerfile is posted for reference with steps to create the production image. Though docker supports Multi-Stage Builds we won’t be using that here since Python needs all the source code and dependencies to be present while running the application. You can opt for multi stage build, if you have any build tool.

# Use an official Python runtime as a parent image
FROM python:3.12-alpine

# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Create and set the working directory
WORKDIR /app

# Copy the requirements file into the container
COPY requirements.txt /app/

# Install utils
RUN apk update
RUN apk upgrade
RUN apk add bash
RUN apk add \
  build-base \
  gcc \
  libc-dev \
  linux-headers \
  python3-dev \
  musl-dev \
  libffi-dev

# Use the custom entrypoint script
COPY entrypoint.sh /app/entrypoint.sh
RUN chmod +x /app/entrypoint.sh
ENTRYPOINT ["/app/entrypoint.sh"]

# Install the project dependencies
RUN pip install -r requirements.txt

# Copy the rest of the application code into the container
COPY . /app/

# Expose the port the app runs on
EXPOSE 8000

# Start the application
CMD ["python", "manage.py", "runserver", "0.0.0.0:8000"]

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Build docker image

Now you can build and run the Docker image. To build the Docker image:

docker build --platform linux/amd64 -t django-todo .

This command builds the django-todo image for platform linux/amd64.

If you are locally testing your application, you can skip the platform key to build the images

# only for testing in local machine
docker build -t django-todo .

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Run the docker image

Let’s run the Docker container using the image created of the react application with the command below.

docker run \
  -it \
  -p 8000:8000 \
  -e DB_HOST=localhost \
  -e DB_PORT=5432 \
  -e DB_NAME=djangotodo \
  -e DB_USER=localops \
  -e DB_PASS=localops \
  --name django-todo \
  django-todo

This command requires PostgresDB to be running on localhost:54321.

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Docker Compose

If you want to run PostgresDB alongside our Django image, then we can create a docker-compose.yml file with below content,

version: '3'

volumes:
  pg_data_todo:

services:
  be:
    build: .
    environment:
      DB_HOST: db
      DB_NAME: todo_db
      DB_USER: todo_user
      DB_PASS: todo_pass
      REDIS_HOST: redis
      S3_REGION: ap-south-1
      AWS_ACCESS_KEY_ID: XYZ
      AWS_SECRET_ACCESS_KEY: XYZ
      S3_BUCKET_NAME: test-bucket
    ports:
      - '8000:8000'
    depends_on:
      - db

  db:
    image: postgres:14.8-alpine3.18
    environment:
      POSTGRES_DB: todo_db
      POSTGRES_USER: todo_user
      POSTGRES_PASSWORD: todo_pass
    volumes:
      - pg_data_todo:/var/lib/postgresql/data
    ports:
      - '5432:5432'

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Docker compose up

docker compose up

After running the command, Visit http://localhost:8000/api/v1/tasks/ to list the tasks.

Hurray 🎉. Now we have created and Dockerized a Python Django app.

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Deploy

You can now commit and push the Dockerfile to your git repo. Create a service now to point at the git repository and branch name to deploy this image.