How to Connect your Django App to a dockerized PostgreSQL and pgAdmin

Docker has been my default environment set-up for deploying most of my web projects quickly. It is lightweight and it has also helped me solve package dependencies and environment configuration issues because it provides a consistent environment across different servers and also makes continuous delivery and deployment enjoyable.

Recently, I felt the need to connect my Django application to a dockerized Postgres database and also manage the database with a dockerized pgAdmin(a web app. for managing Postgres databases).

I did this because I wanted my application layer to stay outside the docker environment of my database without the need to install Postgres and pgAdmin on my local machine for a quick app. prototype.
I had several issues setting this up until I successfully got it up and running.
Let me show you how I did it 😊.

In this post, I am assuming that you have successfully installed Docker and Django. I will also be using docker-compose (this will enable you to run multiple containers).
Visit this link to understand what docker-compose is: https://docs.docker.com/compose/

To dockerize Postgres and pgAdmin:

• create a postgres_docker directory in the root folder that contains your Django project dir.
• cd into the postgres_docker dir. and create a docker-compose file that will contain the Postgres and pgAdmin images: copy the following code and paste it into your docker-compose file

version: "3.1"

services:

  db:
    restart: always
    image: postgres
    container_name: demo-postgres #you can change this
    environment:
      - POSTGRES_USER=demo
      - POSTGRES_PASS=demo
      - POSTGRES_DB=demo
      - POSTGRES_PORT=5432
    ports:
      - "5432:5432"
    volumes:
      - postgres_data:/var/lib/postgresql/data/

  pgadmin:
      image: dpage/pgadmin4
      container_name: demo-pgadmin #you can change this
      depends_on:
        - db
      ports:
        - "5051:80"
      environment:
        PGADMIN_DEFAULT_EMAIL: [e-mail]
        PGADMIN_DEFAULT_PASSWORD: root
      restart: always


volumes:
  postgres_data:

• open your command line, cd into postgres_docker dir. and run

docker-compose up

This command builds, (re)creates, starts, and attaches to containers for a service. to confirm if there are no errors, visit http://localhost:5051 to see pgAdmin Interface.

To connect pgAdmin to Postgres:

• login to pgAdmin with the login details you initialized in the docker-compose file.

 PGADMIN_DEFAULT_EMAIL: [e-mail] #you can change this
 PGADMIN_DEFAULT_PASSWORD: root #you can change this

• enter the following settings from the images below to your pgAdmin interface Please note
• your hostname db is the name of your Postgres service in the docker-compose file.

To connect Django to Postgres:

• In your settings.py, configure database settings like so:

DATABASES = {
    'default': {
        'ENGINE': 'django_postgres_extensions.backends.postgresql',
        'NAME': 'demo',
        'USER': 'demo',
        'HOST': 'localhost',
        'PORT': 5432,
        'PASSWORD':'demo'
    }
}

To see that all went as plan, startup your Django application like so:

python manage.py runserver

If everything works fine, you should see your application without errors.
visit http://localhost:8000

In conclusion, there are several ways to achieve this but this is my preferred way and it also easy to understand.
If you have any issue with your setup leave your comments below.
Kindly follow me and turn on your notification. Thank you!
Happy coding! ✌

Comments

[Laurel German]

A few notes that may be helpful to other beginners like me:

• The docker-compose file should be saved as docker-compose.yaml
• The docker-compose file didn't work as listed, but I changed line 11 to "POSTGRES_PASSWORD=demo" and that worked
• Change the username/password on lines 27-28 of the docker-compose file to your own email address and a NON-PRIVATE password like "demo" or "password" since you're saving it in plain-text
• The username and password on lines 27-28 are what you use to log in to pgadmin. The username and password on lines 10-11 are what you enter in the "Connection" tab when you're creating your database.
• You have to pip install django_postgres_extensions in your django app environment before running runserver, or it won't work

[Philip Mutua]

Hi Micheal thanks. I have a question I have seen some other examples where one does the following:

volumes:
      - ./data/db:/var/lib/postgresql/data

Based on your example above in the docker-compose.yml file under the db service what is the difference?

[Wale Opakunle]

Micheal, I am not sure exactly how to thank you for this article.
Over the last 24 hours, I have been following articles that use the postgres docker container name as the host while connecting to pgadmin and been unable to connect. 24 hours, and I have been pulling my hair out wondering what the hell I was doing wrong.
Thank you. Thank you so much for sharing your knowledge. I can sleep now.

[Hemaz]

Great informations, thanks a lot. I have a question: how can I connect other docker files to Django like what you did with Postgres? I mean how can I connect and consume other model like YoloV5 docker image inside docker?

[Lewis kori]

This is exactly what I needed. Thank you for sharing

[Micheal Ojemoron]

Thanks, I am glad it helped

[itamar27]

Hello, i've been following your instruction but unfortunately I am having some issues which are not mentioned here.

File "C:\Users\Yonatan.virtualenvs\LMS-NZATbBlN\lib\site-packages\django_postgres_extensions\models\expressions.py", line 2, in
from django.utils import six
ImportError: cannot import name 'six' from 'django.utils' (C:\Users\Yonatan.virtualenvs\LMS-NZATbBlN\lib\site-packages\django\utils_init_.py)

This is the error i'm having about some module named "six".

Do you know how to solve this problem?
Haven't found any good answer online

[Guillermo]

Thanks Michael, you saved me a lot of time!

[Micheal Ojemoron]

You are welcome Guillermo

[Philip Mutua]

Hi Micheal, how does one connect to a local MYSQL client using docker compose? If we dont' want to use mysql container?

[perymerdeka]

how to migrate?

[Ricardo Martinez]

sudo docker exec -it python manage.py migrate
but the django HOST variable in the container must be set to
HOST=db

and if you've bind-mounted your code into the container, you can do it directly from the console in your IDE (e.g. vscode) since the container is sharing the exact same code. BUT here HOST=localhost. This means you have to have separate environment variables set. Confusing, but that's what I've noticed.