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

Question

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.

Can you keep postgres container running and restart only django container and tell me if you still getting the same error ? — Mostafa Hussein, Mar 09 '19 at 20:48
Thanks for your comment Mostafa. Apologies I'm still quite new to Docker so may need a hand doing that. I've stopped docker. How can I just get the Postgres container running? Thanks. — shbfy, Mar 09 '19 at 20:56
`docker-compose restart core` this will restart the application without the database so make sure that the database is running first then execute the command — Mostafa Hussein, Mar 09 '19 at 20:57
Are you sure that the postgres container was up and have not restarted while you restarted the application? can you check the up time through `docker ps` ? — Mostafa Hussein, Mar 09 '19 at 21:02
See uptime: `CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 189666f6a2b7 vision_core "python3 manage.py r…" 4 minutes ago Up 3 minutes 0.0.0.0:8000->8000/tcp vision_core_1 af5402d6495f postgres "docker-entrypoint.s…" 4 minutes ago Up 4 minutes 0.0.0.0:32769->5432/tcp vision_db_1` — shbfy, Mar 09 '19 at 21:04
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/189737/discussion-between-mostafa-hussein-and-avocet). — Mostafa Hussein, Mar 09 '19 at 21:05

score 6 · Accepted Answer · answered Jul 02 '19 at 10:05

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.

John Johnson · Answer 2 · 2020-10-07T10:40:01.517

6

Instead of redefining the networks, use

docker-compose down -v

to stop all containers and remove all cached data.

Then

docker-compose up

to restart from scratch.

edited Oct 07 '20 at 10:40

answered Oct 04 '20 at 17:13

John Johnson

543
4
9

score 5 · Answer 3 · answered Oct 04 '19 at 23:25

5

I had to use docker-compose up to make sure my db container was running.

answered Oct 04 '19 at 23:25

dfrankow

20,191
41
152
214

score 3 · Answer 4 · edited Nov 07 '20 at 15:53

I've been searching for several days for the solution to this issue. Here's what I did:

1 - I copied the postgresql.conf.sample file from my postgres container to my project folder you must get in to cd usr/share/postgresql with docker exec -it yourcontainer bash

2 - I changed its name to postgresql.conf

3 - I modified these variables in postgresql.conf

    listen_addresses = '*'
    port = 5432             
    max_connections = 100           
    superuser_reserved_connections = 3
    unix_socket_directories = '/tmp'

4 - I added it to my Dockerfile

COPY postgresql.conf      /tmp/postgresql.conf

5 - settings.py

DATABASES = {
    'default': {
        'ENGINE': 'django.db.backends.postgresql',
        'NAME': 'test',
        'USER': 'testing',
        'PASSWORD': 'tests',
        'HOST': 'localhost',
        'PORT': 5432,
    }
}

6 - I did docker-compose up -build again

score 2 · Answer 5 · edited Apr 19 '20 at 22:53

I came across this issue recently, i solved it by adding postgres environment variables to db in my docker-compose.yml file like so

version: '3'
 services:
  db:
     image: 'postgres'
     ports:
       - '5432'
     environment:
            - POSTGRES_DB=booksdb
            - POSTGRES_USER=postgres
            - POSTGRES_PASSWORD=postgres
  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

score 1 · Answer 6 · answered Sep 24 '20 at 23:59

1

In my specific case, I had postgres without any version, so postgres image gets updated and the db (postgres) container won't get up

answered Sep 24 '20 at 23:59

RobertPro

172
1
13

score 0 · Answer 7 · answered Nov 21 '20 at 21:48

The following configuration works for me from official documentation

version: "3.8"

services:
  db:
    image: postgres
    environment:
      - POSTGRES_DB=postgres
      - POSTGRES_USER=postgres
      - POSTGRES_PASSWORD=postgres

  web:
    build: .
    command: python /code/manage.py runserver 0.0.0.0:8000
    volumes:
      - .:/code
    ports:
      - "8000:8000"
    depends_on:
      - db

then run those commands:

docker-compose up -d --build

docker-compose logs

score 0 · Answer 8 · answered Dec 12 '21 at 20:28

0

docker exec -it "container_name" python3 manage.py migrate

This works for me. Make sure of the path to the manage.py file is correct.

answered Dec 12 '21 at 20:28

Gabriel Bueno

1

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

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