Step by step migration of django cookiecutter postgres to mysql 8+

"Cookiecutter Django is a framework for jumpstarting production-ready Django projects quickly."

So, you recently discovered django-cookiecutter and fell in love with a rather opinionated workflow on how files and services are organized but soon you release that django-cookiecutter does not have support for MySQL databases!

There have been some open issues [1] [2] in their repository but they don't provide an out of the box solution to support MySQL.

Prerequisites

I will assume that you already have installed cookiecutter and have run the below command to initialize your project.

$ cookiecutter https://github.com/pydanny/cookiecutter-django

After the project is bootstrapped, you'd be provided with local.yml file to run your project with docker-compose. We are going to make some changes into the local.yml.

Replace the highlighted blocks with the below code snippet.

# local.yml

version: '3'

services:
  ...
  django:
    ...
    depends_on:
      - postgres
    ...

  postgres:
    build:
      context: .
      dockerfile: ./compose/production/postgres/Dockerfile
    image: my_awesome_project_production_postgres
    container_name: postgres
    volumes:
      - local_postgres_data:/var/lib/postgresql/data:Z
      - local_postgres_data_backups:/backups:z
    env_file:
      - ./.envs/.local/.postgres

  ...

version: '3'

services:
  ...

  django:
    ...
    depends_on:
      - mysql
    ...

  mysql:
      image: mysql:8.0
      command: --default-authentication-plugin=mysql_native_password --mysqlx=0
      container_name: my_awesome_project_local_mysql
      volumes:
        - "./db:/var/lib/mysql"
      ports:
        - '3306:3306'
      env_file:
        - ./.envs/.local/.mysql

  ...

Create a new file at ./.envs/.local/.mysql and paste the following environment variables

# MYSQL

MYSQL_HOST=mysql
MYSQL_PORT=3306
MYSQL_DATABASE=<name-of-your-database>
MYSQL_USER=<name-of-your-mysql-user>
MYSQL_PASSWORD=<some-random-password>
MYSQL_ROOT_PASSWORD=<some-root-random-password>
DATABASE_URL=mysql://<name-of-your-mysql-user>:<some-random-password>@mysql:3306/<name-of-your-database>

Edit the file located in ./compose/local/django/Dockerfile and add the highlighted line

# ./compose/local/django/Dockerfile

FROM python:3.8-slim-buster

...

RUN apt-get update \
  # dependencies for building Python packages
  && apt-get install -y build-essential \
  # psycopg2 dependencies
  && apt-get install -y libpq-dev \
  # install mysql client
  && apt-get install -y default-libmysqlclient-dev \
  # Translations dependencies
  && apt-get install -y gettext \
  # cleaning up unused files
  && apt-get purge -y --auto-remove -o APT::AutoRemove::RecommendsImportant=false \
  && rm -rf /var/lib/apt/lists/*

...

COPY ./compose/production/django/entrypoint /entrypoint

...

ENTRYPOINT ["/entrypoint"]

If you have other docker services that uses django, for example docs service in DockerFile. Edit the Dockerfile to install mysql libraries into those container services too.
replace the content of ./compose/production/django/entrypoint (why production? because of entrypoint mentioned in ./compose/local/django/Dockerfile) with below code snippet to make your django container aware when your database is ready for connection

# ./compose/production/django/entrypoint

#!/bin/bash

set -o errexit
set -o pipefail
set -o nounset



export DATABASE_URL="mysql://${MYSQL_USER}:${MYSQL_PASSWORD}@${MYSQL_HOST}:${MYSQL_PORT}/${MYSQL_DATABASE}"

echo $DATABASE_URL

mysql_ready() {
python << END
import sys
import mysql.connector

try:
    mysql.connector.connect(
      host="${MYSQL_HOST}",
      user="${MYSQL_USER}",
      password="${MYSQL_PASSWORD}",
    )
except Exception as e:
    print('Exception at entrypoint file', e)
    sys.exit(-1)
sys.exit(0)

END
}
until mysql_ready; do
  >&2 echo 'Waiting for MySQL to become available...'
  sleep 1
done
>&2 echo 'Mysql is available'

exec "$@"

Add the requirement in pip's requirement file ./requirements/base.txt


...
mysql-connector-python==8.0.22
mysqlclient==2.0.1
...

Run the docker-compose

At this point of time, your project should be able to run below commands successfully

$ docker-compose -f local.yml build
$ docker-compose -f local.yml up

##Changes for production.yml

Follow the similar approach to edit the required files to setup your production.yml to work for mysql container service.