Containerization has become a standard practice in modern software development, providing consistency across various stages of development and deployment. In this guide, we will dockerize a Django application with Traefik for reverse proxying and automatic SSL with Let's Encrypt, Celery for asynchronous task processing, Redis for caching, RabbitMQ for message brokering, and Celery Beat for periodic tasks.

Prerequisites

Ensure you have Docker and Docker Compose installed on your machine. Here is the official link for installation instructions: https://docs.docker.com/engine/install/

Project Setup

If you don't have a Django project yet, you can create one with the following commands:

mkdir dummy_project
cd dummy_project
django-admin startproject config
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dummy_project is the root project directory.

I generally rename the base config directory to src, once the project is created for better naming conventions and consistency across projects.

Next, create a Django app:

python manage.py startapp myapp
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Update your Django settings to use the Postgres database, configure Celery, Redis and RabbitMQ. Add your business logic as needed.

It’s recommended to create different environments[dev, staging, prod] for your project by setting up separate settings, .env, requirements.txt, and docker-compose files. For reference, you can use this: https://github.com/priyanshu2015/best-django-boilerplate.

Docker Setup

Dockerfile

Create a Dockerfile in the root directory of your project:

# Use the official Python image from the Docker Hub
FROM python:3.9-slim

# Set environment variables
ENV PYTHONDONTWRITEBYTECODE 1
ENV PYTHONUNBUFFERED 1

# Set work directory
RUN mkdir /code
WORKDIR /code

# Install dependencies
COPY requirements.txt /code/
RUN pip install -r requirements.txt

# Copy project
COPY . /code/
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docker-compose.yml

Create a docker-compose.yml file to define the services:

version: '3.9'

services:
  django:
    build:
      context: .
      dockerfile: Dockerfile
    command: sh -c "python manage.py migrate && gunicorn config.wsgi:application --bind 0.0.0.0:8000"
    volumes:
      - static_volume:/code/static
      - media_volume:/code/media
    environment:
      - DJANGO_SETTINGS_MODULE=myproject.settings
    labels:
      - "traefik.enable=true"
      - "traefik.http.routers.dummy-project-api.rule=Host(`yourdomain.com`)"
      - "traefik.http.routers.dummy-project-api.entrypoints=websecure"
      - "traefik.http.routers.dummy-project-api.tls.certresolver=myresolver"
      - "traefik.http.services.dummy-project-api.loadbalancer.server.port=8000"
    depends_on:
      - migrate
      - redis
      - rabbitmq
    # to keep the log file within a certain limit
    logging:
      driver: "json-file"
      options:
        max-size: "100m"
        max-file: "5"

  db:
    image: postgres:13
    volumes:
      - postgres_data:/var/lib/postgresql/data
    environment:
      - POSTGRES_DB=dummy_db
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
    logging:
      driver: "json-file"
      options:
        max-size: "100m"
        max-file: "5"

  migrate:
    build:
      context: .
      dockerfile: Dockerfile
    command: bash -c "python manage.py migrate"
    env_file:
      - .env
    logging:
      driver: "json-file"
      options:
        max-size: "170m"
        max-file: "5"
    depends_on:
      - db

  redis:
    image: redis:6
    volumes:
      - redis-data:/var/lib/redis/data/
    logging:
      driver: "json-file"
      options:
        max-size: "100m"
        max-file: "5"

  rabbitmq:
    build:
      context: .
      dockerfile: Dockerfile.rabbitmq
    ports:
      - "5672:5672"
      - "15672:15672"
    logging:
      driver: "json-file"
      options:
        max-size: "170m"
        max-file: "5"

  celery:
    build:
        context: .
        dockerfile: Dockerfile
    command: sh -c "celery -A config worker -l info  worker -E --pool=threads --concurrency=10 -l info --without-gossip --without-mingle"
    env_file: .env
    depends_on:
      - migrate
      - redis
      - rabbitmq
    logging:
      driver: "json-file"
      options:
        max-size: "170m"
        max-file: "5"

  celery-beat:
    build:
        context: .
        dockerfile: Dockerfile
    command: sh -c "celery -A config beat -l info"
    env_file: .env
    depends_on:
      - migrate
      - redis
      - rabbitmq
    logging:
      driver: "json-file"
      options:
        max-size: "170m"
        max-file: "5"

  traefik:
    image: "traefik:v2.9"
    container_name: "traefik"
    command:
      #- "--log.level=DEBUG"
      - "--api.insecure=true"
      - "--providers.docker=true"
      - "--providers.docker.endpoint=unix:///var/run/docker.sock"
      - "--providers.docker.exposedbydefault=false"
      - "--providers.docker.network=traefik-public"
      - "--entrypoints.websecure.address=:443"
      - "--certificatesresolvers.myresolver.acme.tlschallenge=true"
      #- "--certificatesresolvers.myresolver.acme.caserver=https://acme-staging-v02.api.letsencrypt.org/directory"
      - "--certificatesresolvers.myresolver.acme.email=your-email@example.com"
      - "--certificatesresolvers.myresolver.acme.storage=/letsencrypt/acme.json"
    ports:
      - "443:443"
      - "8080:8080"
    volumes:
      - /var/run/docker.sock:/var/run/docker.sock
      - traefik_letsencrypt:/letsencrypt
    networks:
      - traefik-public
    logging:
      driver: "json-file"
      options:
        max-size: "100m"
        max-file: "5"

volumes:
  postgres_data:
  traefik_letsencrypt:
  static_volume:
  media_volume:
  redis-data:

networks:
  traefik-public:
    external: true
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Replace your-email@example.com with the email with which you purchased your domain. You may need to adjust configurations according to your project requirements.

RabbitMQ configurations

I use a custom RabbitMQ image to fine-tune its configurations.

Create Dockerfile.rabbitmq

FROM rabbitmq:3-management
COPY ./rabbitmq/rabbitmq.config /etc/rabbitmq
ADD --chown=rabbitmq ./rabbitmq/definitions.json /etc/rabbitmq/
RUN chown rabbitmq:rabbitmq /etc/rabbitmq/rabbitmq.config /etc/rabbitmq/definitions.json
CMD ["rabbitmq-server"]
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Create rabbitmq directory in the root project directory

Create definitions.json file

{
    "users": [
      {
        "name": "guest",
        "password_hash": "Hf5vYMsz5ANOelI10vIHeVnGBlBZOhWIOWM2pwBtkWgAEKRv",
        "hashing_algorithm": "rabbit_password_hashing_sha256",
        "tags": "administrator"
      }
    ],
    "vhosts": [
      {
        "name": "/"
      }
    ],
    "permissions": [
      {
        "user": "guest",
        "vhost": "/",
        "configure": ".*",
        "write": ".*",
        "read": ".*"
      }
    ],
    "parameters": [],
    "policies": [],
    "queues": [],
    "exchanges": [],
    "bindings": []
  }
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Create rabbitmq.config file

[
  {rabbit, [
    {loopback_users, []}
  ]},
  {rabbitmq_management, [
    {load_definitions, "/etc/rabbitmq/definitions.json"}
  ]}
].
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Running the Application

Build and run the Docker containers using Docker Compose:

docker-compose up --build -d
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Check if everything is working fine

docker ps
docker logs <container_id>
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To Enter the Django Container and Interact via Shell

docker exec -ti <djanggo_container_id> bash
python manage.py shell
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Test your application to ensure everything is functioning correctly. You may need to use additional Docker commands to manage your containers. Check all Docker commands: https://docs.docker.com/get-started/docker_cheatsheet.pdf

Conclusion

In this blog, we've walked through the process of Dockerizing a Django application with Traefik for reverse proxying and Let's Encrypt for automatic SSL, Celery for asynchronous task processing, Redis for caching, RabbitMQ for message brokering, and Celery Beat for periodic tasks. This setup ensures a robust environment for developing and deploying Django applications with asynchronous task processing capabilities. Docker and Docker Compose simplify the management of these services, allowing you to focus on writing code rather than managing infrastructure.