[FIXED] Django docker - could not translate host name "db" to address: nodename nor servname provided, or not known

Issue

I'm relatively new to Django and Docker and am following a tutorial to build a mini application. However, I'm getting stuck with the following error:

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

My docker-compose file looks as follows:

 version: '3'
 services:
  db:
     image: 'postgres'
     ports:
       - '5432'
  core:
    build:
      context: .
      dockerfile: Dockerfile
    command: python3 manage.py runserver 0.0.0.0:8000
    ports:
      - '8000:8000'
    volumes:
      - .:/code
    depends_on:
      - db
    links:
      - db:db

My settings.py file contains the database:

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

I've seen the post here and here however both have not fixed the issue.

Would appreciate some guidance. Thanks.

Solution

So you are trying to reach the db which is running in one container from another container? If yes - the following could potentially help, at least it helped me when I had similar issues.

Try to define networks config in addition to links in your compose file, create a network with some name and define it in both services. Like described here, as the docks on links config recommend to do that.

Something like this for your case:

version: '3'
 services:
  db:
     image: 'postgres'
     ports:
       - '5432'
     networks:
      some_network:
  core:
    build:
      context: .
      dockerfile: Dockerfile
    command: python3 manage.py runserver 0.0.0.0:8000
    ports:
      - '8000:8000'
    volumes:
      - .:/code
    depends_on:
      - db
    links:
      - db:db
    networks:
      some_network:
  networks:
   some_network:

It helped me to resolve the host name to connect to the db.

Answered By - Rocckk