How to Connect your MySQL Database to your Dockerized Django Application

Running an example project first

In this first section, I will walk you through how you can get a running example working on your local machine. You will clone a repo I have prepared and run through the steps to get it working locally, then I will go through how I created this example.

Check out the repo here

Clone my repo


cd user/Github # (or wherever)
git clone https://github.com/JamesDHW/blog-docker-django-mysql.git
cd docker-django-mysql

Build and run the container


docker-compose build # build the container
docker-compose up -d # run the container as a daemon

Go to localhost:8000 and you should now see a basic Django page running. That's it - everything should be connected and ready for development! Just to be sure, let's do some checks to see that everything is doing what we expect.

There are two services - web (where Django runs) and db (where MySQL runs) - which we will run a bash for each service and have a look at what's going on for each one.

Checking it works: Run the `web` service


# open a bash for the web container
docker-compose exec web bash
ping db # ping the db service.

Expected output:


...
64 bytes from docker-django-mysql_db_1.docker-django-mysql_default (172.22.0.2): 
icmp_seq=27 ttl=64 time=0.220 ms
64 bytes from docker-django-mysql_db_1.docker-django-mysql_default (172.22.0.2): 
icmp_seq=28 ttl=64 time=0.451 ms
...

This shows that your web service can talk to your db service. You can also run:


ps aux | grep mysql

to get any process that's running which contains mysql in the name - if you get output, a process has been found.

Quit the bash shell for web with cntrl+d.

Checking it works: Run the `db` service


# open a bash for the `db` container
docker-compose exec db bash

# (where `root` is username and `my-app-db` is the database name)
mysql -u root -p my-app-db

type in your password (password).

You should now be connected to the mysql client for your database.


# view all the tables (should be none)
SHOW TABLES 

# create a table (you can press enter, the command is only executed after a `;`)
CREATE TABLE users ( firstName varchar(255) ); 

# see the table you created
SHOW TABLES

Quit the bash shell for db with cntrl+d.

If you've followed until now, you should have a working example of a Django app, running in Docker and connected to a MySQL database. Read on for more details on how I created this repo and the steps you'll need to take to replicate it in your own project.

How I made this project

Now that we know this is working, let's see how I made the project from scratch!


# make new git repo
mkdir DockerMySQL
cd DockerMySQL
git init
git remote add origin... 

# django init new project
python -m django startproject DockerMySQL

Add a `Dockerfile`

In the root of the project I added a Dockerfile to define the dependencies (etc.) for the container I want.


FROM python:3.6
ENV PYTHONUNBUFFERED 1

RUN pip install --upgrade pip

COPY ./requirements.txt /requirements.txt
RUN pip install -r /requirements.txt

RUN mkdir /DockerMySQL
WORKDIR /DockerMySQL
COPY ./DockerMySQL /DockerMySQL

Add a `docker-compose.yml`

I then created a docker-compose.yml to define two services, one to run the database on (called db) and one to run the Django site on (called web).


version: '3'

services:
  db:
    image: mysql:5.7
    ports:
      - '3306:3306'
    environment:
       MYSQL_DATABASE: 'my-app-db'
       MYSQL_ROOT_PASSWORD: 'password'
  web:
    build: .
    command: python manage.py runserver 0.0.0.0:8000
    volumes:
      - ./DockerMySQL:/DockerMySQL
    ports:
      - "8000:8000"
    depends_on:
      - db

Add a `requirements.txt`

I now actually define what the requirements for the Django app will be in requirements.txt.


Django==1.11.5
mysqlclient==1.3.12
django-mysql==2.2.0

In `settings.py` add `DATABASES` variable


DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.mysql',
        'NAME': 'my-app-db',
        'USER': 'root',
        'PASSWORD': 'password',
        'HOST': '192.168.1.97',
        'PORT': 3306,
    }
}

Remove the default `DATABASES` variable

View the commit here


DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.sqlite3',
        'NAME': os.path.join(BASE_DIR, 'db.sqlite3'),
    }
}

Summary

This should have been a clear step by step how-to on creating a Django app that connects to MySQL. If you want to look at any files more specifically, you can always check the repo here. Happy coding!