How to properly populate Docker Django image with data from Postgres? - django

Question

I wanted to create a Docker image for my Django project called mysite that has two apps tracks and users. I used docker build -t mysite to build my docker image. I have written a Dockerfile like it says on dockerhub. Then I created docker-compose.yml file and bash script entypoint.sh that I use in docker-compose file.
These are my files:
Dockerfile:
FROM django:onbuild
COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh
docker-compose.yml:
version: '3'
services:
db:
image: postgres
restart: always
container_name: postgres_container
environment:
- POSTGRES_USER=postgres
- POSTGRES_PASSWORD=postgres
- POSTGRES_DB=postgres
- DJANGO_SETTINGS_MODULE=mysite.settings_docker
ports:
- 5432:5432
volumes:
- /var/lib/postgresql/10/main
web:
image: mysite:latest
build:
context: .
dockerfile: Dockerfile
container_name: mysite_container
ports:
- "8000:8000"
depends_on:
- db
environment:
- DJANGO_SETTINGS_MODULE=mysite.settings_docker
entrypoint.sh
#!/bin/sh
python manage.py makemigrations
python manage.py migrate
python manage.py runserver 0.0.0.0:8000
exec "$#"
So when I wanted to start the whole container I used following commands
docker build .
docker-compose build
docker-compose up
My database in settings.py is
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'postgres',
'USER': 'postgres',
'PASSWORD': 'postgres',
'HOST': 'localhost',
'PORT': '5432',
}
}
My database in settings_docker.py, that I use in container is
DATABASES = {
'default': {
'ENGINE': 'django.db.backends.postgresql_psycopg2',
'NAME': 'postgres',
'USER': 'postgres',
'PASSWORD': 'postgres',
'HOST': 'db',
'PORT': '5432',
}
}
Then I added new settings_docker.py where I set my host to 'db' (In original settings.py I have HOST='localhost' and when I start the Django app with python manage.py runserver I have all my tables and relations froPostgreses database) file and added environment variable DOCKER_SETTINGS_MODULE=mysite.settins_docker to my web service in docker-compose.yml and the container starts properly, but now I don't have my database relations and tables.
So, how can I migrate those relations to docker? Which is the right way to populate my docker container with relations from postgres? I have tried with volumes in docker-compose.yml where I specified my postgres data file (my data is in /var/lib/postgresql/10/main) but it's still not working.

Answer 1

In case you consider switching to another approach - a native and quite portable* solution for providing an initial state of a DB would be to utilize Django fixtures. Utilizing that method, you have to bring your DB state into an expected state, meaning to provide initial tables and records. When ready, perform:
python manage.py dumpdata
In order to store the data in a file. Then, reuse the saved file with:
python manage.py loaddata fixturename
Another, but less flexible, way would be to provide .sql file to a init-db location - read in the manual where that is depending specifically on your Postgres version.
*portable, meaning you can maneuver with the file, send it, edit it and easily apply it.