manage.py test error in Django involving django.db.utils.OperationalError

Question

I receive the following error when I run python manage.py test

django.db.utils.OperationalError: could not translate host name "db" to address: nodename nor servname provided, or not known

My docker-compose.yml looks like this:

version: '3'

services:
  db:
    image: postgres
    ports:
      - "5432:5432"
  web:
    entrypoint: /entrypoint.sh
    build: .
    command: python3 manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db

My dockerfile looks like

FROM python:3
ENV PYTHONUNBUFFERED 1
RUN mkdir /code
WORKDIR /code
ADD requirements.txt /code/
RUN pip install -r requirements.txt
ADD . /code/
COPY entrypoint.sh /entrypoint.sh
RUN chmod +x /entrypoint.sh

Please give me any insight on how to resolve this issue.

Answer 1

It's because they are not in the same network,

You should create a network and include both db and web in it,

version: '3'

services:
  db:
    image: postgres
    ports:
      - "5432:5432"
    networks:
      - backend


  web:
    entrypoint: /entrypoint.sh
    build: .
    command: python3 manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db
    networks:
      - backend

networks:
  backend:
    driver: bridge

Answer 2

Be careful NOT TO EXPOSE PORTS FOR THE DB .

version: '3'

services:
  db:
    image: postgres
  environment:
    POSTGRES_PASSWORD: <password>
    POSTGRES_USER: postgres
  networks:
    - backend

In your Django settings.py, you can now use db as your hostname instead of localhost.

DATABASES = {'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'postgres',                      
        'USER': 'postgres',
        'PASSWORD': '<password>',
        'HOST': 'db',
        'PORT': '5432', 
    }}

Your web service stays as it is because this one needs the container's port 8000 bound to your localhost:8000