How do you perform Django database migrations when using Docker-Compose?

Question

I have set up a Docker Django/PostgreSQL app closely following the Django Quick Start instructions on the Docker site.

The first time I run Django's manage.py migrate, using the command sudo docker-compose run web python manage.py migrate, it works as expected. The database is built inside the Docker PostgreSQL container just fine.

Changes made to the Django app itself are likewise reflected in the Docker Django container, the moment I save them. It's great!

But if I then change a model in Django, and try to update the Postgres database to match the model, no changes are detected so no migration happens no matter how many times I run makemigrations or migrate again.

Basically, every time I change the Django model, I have to delete the Docker containers (using sudo docker-compose rm) and start afresh with a new migration.

I'm still trying to get my head around Docker, and there's an awful lot I don't understand about how it works, but this one is driving me nuts. Why doesn't migrate see my changes? What am I doing wrong?

Answer 1

You just have to log into your running docker container and run your commands.

1. Build your stack : docker-compose build -f path/to/docker-compose.yml
2. Launch your stack : docker-compose up -f path/to/docker-compose.yml
3. Display docker running containers : docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                         NAMES
3fcc49196a84        ex_nginx          "nginx -g 'daemon off"   3 days ago          Up 32 seconds       0.0.0.0:80->80/tcp, 443/tcp   ex_nginx_1
66175bfd6ae6        ex_webapp         "/docker-entrypoint.s"   3 days ago          Up 32 seconds       0.0.0.0:32768->8000/tcp       ex_webapp_1
# postgres docker container ...

4. Get the CONTAINER ID of you django app and log into :

docker exec -t -i 66175bfd6ae6 bash

5. Now you are logged into, then go to the right folder : cd path/to/django_app

6. And now, each time you edit your models, run in your container : python manage.py makemigrations and python manage.py migrate

I also recommend you to use a docker-entrypoint for your django docker container file to run automatically :

• collecstatic
• migrate
• runserver or start it with gunicorn or uWSGI

Here is an example (docker-entrypoint.sh) :

#!/bin/bash

# Collect static files
echo "Collect static files"
python manage.py collectstatic --noinput

# Apply database migrations
echo "Apply database migrations"
python manage.py migrate

# Start server
echo "Starting server"
python manage.py runserver 0.0.0.0:8000

Answer 2

I use this method:

services:
  web:
    build: .
    image: uzman
    command: python manage.py runserver 0.0.0.0:8000
    ports:
      - "3000:3000"
      - "8000:8000"
    volumes:
      - .:/code
    depends_on:
      - migration
      - db
  migration:
    image: uzman
    command: python manage.py migrate --noinput
    volumes:
      - .:/code
    depends_on:
      - db

Using docker hierarchy we made, the service migration runs after setting up the database and before running the main service. Now when you run your service docker will run migrations before running the server; look that the migration server is applied over the same image as the web server, it means that all migrations will be taken from your project, avoiding problems.

You avoid making entry points or whatever other thing this way.

Answer 3

Have your stack running then fire off a one shot docker-compose run command. E.g

#assume django in container named web
docker-compose run web python3 manage.py migrate

This works great for the built-in (default) SQLite database, but also for an external dockerized database that's listed as dependency. Here's an example docker-compose.yaml file

version: '3'

services:
  db:
    image: postgres
  web:
    build: .
    command: python manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db

https://docs.docker.com/compose/reference/run/

Answer 4

You can use docker exec command

docker exec -it container_id python manage.py migrate

Answer 5

you can use docker-entrypoint.sh or a newer solution would be multiple comments in your docker-compose.yml

version: '3.7'

services:
  web:
    build: ./
    command: >
      sh -c "python manage.py collectstatic --noinput &&
             python manage.py migrate &&
             python manage.py runserver 0.0.0.0:8000"
    volumes:
      - ./:/usr/src/app/
    ports:
      - 8000:8000
    env_file:
      - ./.env
    depends_on:
      - postgres

  postgres:
    image: postgres:13.0-alpine
    ports:
      - 5432:5432
    volumes:
      - ./data/db:/var/lib/postgresql/data
    environment:
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres
      - POSTGRES_DB=postgres

Answer 6

If you have something like this in your docker-compose.yml

version: "3.7"

services:

  app:
    build:
      context: .
      dockerfile: docker/app/Dockerfile
    ports:
    - 8000:8000
    volumes:
        - ./:/usr/src/app
    depends_on:
      - db

  db:
    image: postgres
    restart: always
    environment:
      POSTGRES_USER: docker
      POSTGRES_PASSWORD: docker
      POSTGRES_DB: docker

Then you can simple run...

~$ docker-compose exec app python manage.py makemigrations
~$ docker-compose exec app python manage.py migrate

Answer 7

Using docker exec, I was getting the following error:

AppRegistryNotReady("Models aren't loaded yet.")

So I used this command instead:

docker-compose -f local.yml run django python manage.py makemigrations

Answer 8

I know this is old, and maybe I am missing something here (if so, please enlighten me!), but why not just add the commands to your start.sh script, run by Docker to fire up your instance? It will take only a few extra seconds.

N.B. I set the DJANGO_SETTINGS_MODULE variable to make sure the correct database is used, as I use different databases for development and production (although I know this is not 'best practice').

This solved it for me:

#!/bin/bash
# Migrate the database first
echo "Migrating the database before starting the server"
export DJANGO_SETTINGS_MODULE="edatool.settings.production"
python manage.py makemigrations
python manage.py migrate
# Start Gunicorn processes
echo "Starting Gunicorn."
exec gunicorn edatool.wsgi:application \
    --bind 0.0.0.0:8000 \
    --workers 3

Answer 9

If you only want to use Dockerfile, you can add ENTRYPOINT[] command. Example how to run .sh script:

FROM python:3.9.4
RUN apt-get update
RUN apt-get install libpq-dev --assume-yes
RUN pip3 install psycopg2

COPY . /app
WORKDIR /app

RUN pip install -r requirements.txt
RUN pip3 install debugpy

ENTRYPOINT ["/app/docker-entrypoint.sh"]

CMD ["python", "manage.py", "runserver", "0.0.0.0:8000"]