Using PostgreSQL with Django

This blog post will act as a personal reminder of configuring Postsgres for a Django project.

Create Database

Start Postgres:

sudo service postgresql start

Log-in to a Postgres interactive session:

sudo -u postgres psql

Create a database for the Django project. My project is called ar10_tracker so I'll name my database the same:

CREATE DATABASE ar10_tracker;

Create a user and password to interact with the database:

CREATE USER myuser WITH PASSWORD 'mypassword';

We can change configuration settings to optimise the performance of the database. See documentation for more information.

ALTER ROLE myuser SET client_encoding TO 'utf8';

ALTER ROLE myuser SET default_transaction_isolation TO 'read committed';

ALTER ROLE myuser SET timezone TO 'UTC';

Next we give the ar10user the required privileges to have full control over the database:

GRANT ALL PRIVILEGES ON DATABASE ar10_tracker TO myuser;

The postgres database is now setup and we can exit the interactive session:

\q

Add required dependencies

To connect to Postgres I'll need a database adapter. I'm using psycopg2. Additionally to configure the database settings I require dj_database_url and python-decouple.

echo psycopg2~=2.9.5 >> requirements.in
echo dj-database-url 1.2.0 >> requirements.in
echo python-decouple==3.7 >> requirements.in
pip-compile requirements.in
python -m pip install requirements.txt

dj_database_url is a utility which uses a DATABASE_URL environment variable to create a dictionary containing the data specified in the DATABASE_URL string.

For example, passing the url schema for a Postgres database postgres://myuser:mypassword@127:0.0.1:5432/ar10_tracker to dj_database_url.config() will return the following dictionary:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'ar10_tracker',
        'USER': 'myuser',
        'PASSWORD': 'mypassword',
        'HOST': '127.0.0.1',
        'PORT': '5432',
    }
}

python-decouple provides the functionality to separate project settings from code. I can store sensitive data such as database credentials in a separate .env file and load them as environment variables at runtime. In this Django project I'm using python-decouple to load secret key, debug status, allowed hosts and database connection credentials.

Generating a secret key for Postgres database

python -c "from django.core.management.utils import get_random_secret_key; print(get_random_secret_key())"

Utilise a .env file to store sensitive environment variables

The .env file contains the following variables:

SECRET_KEY=
DEBUG=
ALLOWED_HOSTS=
DATABASE_URL=

Configure Django project settings.py file to use Postgres database

Add the following imports to settings.py:

import dj_database_url
from decouple import Csv, config

Update the DATABASES variable in settings.py to utlise dj_database_url:

DATABASES = {"default": dj_database_url.config(default=config("DATABASE_URL"))}

The following default variables are removed:

# SECURITY WARNING: keep the secret key used in production secret!
SECRET_KEY = "django-insecure-z_)j=_h=5fmfob9l#vm)p)(#w7-w-v!p57eh^=36-jfmcoaf7t"

# SECURITY WARNING: don't run with debug turned on in production!
DEBUG = True

ALLOWED_HOSTS = []

and updated to utilise the python-decouple config function to load environment variables from the .env file:

SECRET_KEY = config("SECRET_KEY")
DEBUG = config("DEBUG", default=False, cast=bool)
ALLOWED_HOSTS = config("ALLOWED_HOSTS", cast=Csv())

I used the following article as a guide: https://www.digitalocean.com/community/tutorials/how-to-use-postgresql-with-your-django-application-on-ubuntu-20-04