Docker django.db.utils.OperationalError: could not translate host name "db" to address: Temporary failure in name resolution

Question

Seems like a common error. I followed every possible suggestion on Stackoverflow(adding links, network etc), but it makes no difference in my case. I am running on Windows.

My Dockerfile:

#Pull base image.
FROM python:3.9.5-slim

#Usefull to get logs
ENV PYTHONUNBUFFERED 1

#Make local dir
RUN mkdir -p /app

#set as the working directory
WORKDIR /app

#https://luis-sena.medium.com/creating-the-perfect-python-dockerfile-51bdec41f1c8
COPY requirements.txt .

#now copy all the files in this directory to \code
ADD . .

#https://testdriven.io/blog/dockerizing-django-with-postgres-gunicorn-and-nginx/
RUN apt-get update && \
 apt-get install -y postgresql-server-dev-all gcc python3-dev musl-dev && \
 pip install -r requirements.txt && \
 adduser --disabled-password --no-create-home app

USER app

#CMD python manage.py runserver
CMD gunicorn --bind 0.0.0.0:8000 app.wsgi:application -k eventlet

Next, my docker-compose.yml:

services:
  web:
    build: .
    ports:
      - "8000:8000"
    volumes:
      - .:/app
    links:
      - db:db
    container_name: heritageapi_web_1
    depends_on:
      - db
    networks:
      - heritage-network

  db:
    image: postgres:13.3
    container_name: db
    restart: always
    networks:
      - heritage-network
    environment:
      POSTGRES_DATABASE: admin
      POSTGRES_USER: root
      POSTGRES_PASSWORD: root
      POSTGRES_ROOT_PASSWORD: root
    volumes:
      - .dbdata:/var/lib/postgres
    ports:
      - "32768:5432"

networks:
  heritage-network:
    driver: bridge

My .env:

DB_NAME=admin 
DB_USER=root 
DB_PASSWORD=root 
DB_HOST=db 
DB_PORT=5432

Finally my settings.py:

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': os.getenv('DB_NAME'),
        'USER': os.getenv('DB_USER'),
        'PASSWORD': os.getenv('DB_PASSWORD'),
        'HOST': os.getenv('DB_HOST'),
        'PORT': os.getenv('DB_PORT'),
    }
}

Answer 1

I don't see .env file in web container. It should be something like that:

services:
  web:
   depends_on:
    - db
   env_file:
    - .env.dev

If everything works then enter running docker container with docker-compose exec and print

python manage.py shell
>> from django.conf import settings
>> settings.DB_HOST