How to expose a docker container to access host database? - django

Question

I'm currently trying to figure out how to configure my docker-compose.yml to allow a web-server (django) to communicate with a PostgreSQL database running on the host machine.
The app is perfectly working outside of a container.
And now I want to create a container for better management and deployment capabilities.
I've tried this,
docker-compose.yml :
version: '3'
services:
web:
image: myimage
volumes:
- .:/appdir
environment:
- DB_NAME=test
- DB_USER=test
- DB_PASSWORD=test
- DB_HOST=localhost
command: python manage.py runserver 0.0.0.0:8000
ports:
- "8000:8000"
networks:
- mynet
networks:
mynet:
Dockerfile :
FROM python:3
ENV PYTHONUNBUFFERED=1 \
DJANGO_SETTINGS_MODULE=app.settings \
DEBUG=True \
SECRET_KEY=akey
WORKDIR /appdir
COPY . /appdir
EXPOSE 8000
RUN pip install -r requirements.txt
But when I do so, I get the following error :
web_1 | django.db.utils.OperationalError: could not connect to server: Connection refused
web_1 | Is the server running on host "localhost" (127.0.0.1) and accepting
web_1 | TCP/IP connections on port 5432?
Thanks

Answer 1

localhost is relative - inside the docker container - localhost (aka 127.0.0.1) refers to the container itself. if you want to connect to your host- give the container your host real ip as the DB_HOST.
there are many ways to find your host ip, for instance:
run in your terminal hostname -I | awk '{print $1}'