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Dockerized PostgreSQL and Django for Local Development

Docker and docker-compose make it dead simple to avoid dependency hell and have a consistent environment for your whole team while doing local development. This post walks through setting up a new Django project from scratch to use Docker and docker-compose. It is modeled after a previous post that I wrote about doing a similar thing with Laravel and MySQL.

Dockerfile

Nothing too interesting happening here. Installing python and pip.

FROM ubuntu:16.04

# system update
RUN apt update
RUN apt upgrade -y

# python deps
RUN apt install -y python3-dev python3-pip

docker-compose.yml

version: '2'
services:
  app:
    build: .
    ports:
      - "8000:8000"
    volumes:
      - .:/app
    working_dir: /app
    command: bash -c "pip3 install -r requirements.txt && python3 manage.py migrate && python3 manage.py runserver 0:8000"
    depends_on:
      - db
  db:
    image: postgres:9.6.5-alpine
    environment:
      - POSTGRES_USER=feedread
      - POSTGRES_PASSWORD=feedread
    volumes:
      - ./data:/var/lib/postgresql/data
    ports:
      - "5432:5432"

With this in place you can start your Django app with docker-compose up. Each time the app starts it will install the latest dependencies, run migrations, and start serving the app on localhost:8000

Notes

  1. In order to do stuff with the database locally you should add the following record to your local /etc/hosts file 
    # /etc/hosts

127.0.0.1 db
  2. Since we define – .:/app as a volume, this means that all of your local changes are immediately visible in the dockerized app.
  3. If you need to access the running app or db container you can do so with docker-compose exec app bash or docker-compose exec db bash.
  4. This docker-compose file is not really suitable for production since it is not likely that you would want to build the container each time the app starts or automatically run migrations.
  5. You can add additional services like memcached, a mail server, an app server, a queue, etc., using the same method that we are using above with our database.

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