Struggling with connection between Django and Postgres within Docker containers

Question

I've been hitting the following error for awhile now and can't seem to fix it...

django.db.utils.OperationalError: could not connect to server: Connection refused
Is the server running on host "127.0.0.1" and accepting
TCP/IP connections on port 5432?

Multiple resources stated it was simply due to the HOST setting within my DATABASES, but the following is what I am working with and still can't get it to work:

DATABASES = {
    'default': {
        'HOST': 'db',
        'ENGINE': 'django_postgrespool2',
        'NAME': os.environ.get('PROJECT_HEARSAY_DB_NAME'),
        'USER': os.environ.get('PROJECT_HEARSAY_DB_USER'),
        'PASSWORD': os.environ.get('PROJECT_HEARSAY_DB_PASSWORD'),
        'PORT': os.environ.get('PROJECT_HEARSAY_DB_PORT'),
    }
}

Here is the Dockerfile for my Django app:

FROM python:3
ENV PYTHONUNBUFFERED 1
COPY . /app
WORKDIR /app
RUN pip install --upgrade pip
RUN pip install -r requirements.txt

Here is the Dockerfile for my Postgresql DB:

FROM postgres

And here is the docker-compose.yml that I am working with:

version: "3"

services:

  postgresql:
    build:
      context: ./db
    container_name: db.postgresql
    ports:
      - 5432:5432
    environment:
      POSTGRES_DB: "db_name"
      POSTGRES_USER: "username"
      POSTGRES_PASSWORD: "password"

  django:
    restart: always
    build:
      context: ./api
    command:  bash -c "./manage.py migrate && ./manage.py runserver 0.0.0.0:8000"
    container_name: api.django
    ports:
      - 8000:8000
    depends_on:
      - postgresql

I'm curious if anyone here could shed some light on what I am doing wrong.

Thank you.

Adiii · Accepted Answer · 2019-10-02 19:57:49Z

2

Your container name is db.postgresql, so your connection string should be db.postgresql or postgresql in the host name.

DATABASES = {
    'default': {
        'HOST': 'db.postgresql',
        'ENGINE': 'django_postgrespool2',
        'NAME': os.environ.get('PROJECT_HEARSAY_DB_NAME'),
        'USER': os.environ.get('PROJECT_HEARSAY_DB_USER'),
        'PASSWORD': os.environ.get('PROJECT_HEARSAY_DB_PASSWORD'),
        'PORT': os.environ.get('PROJECT_HEARSAY_DB_PORT'),
    }
}

you can verify the connection

docker exec api.django bash -c "nslookup db.postgresql"

You will get the Postgres container IP inside your Django container.

edited Oct 2, 2019 at 19:57

answered Oct 2, 2019 at 19:47

Adiii

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5 Comments

Bonteq Over a year ago

Hey, I appreciate the response. I deleted all containers and images, applied your changes, and rebuilt using docker-compose up and am getting the same error. As for your connection test, it is giving me a bash: nslookup: command not found

Adiii Over a year ago

So ns lookup is not installed on your docker image and it should not point to 127.0.0.1 in connection

Bonteq Over a year ago

Do you mind explaining what you mean by it should not point to 127.0.0.1 in connection? I'm unsure of what you are referring too. I believe that is the default Django points too, but I thought I was altering that with the command command: bash -c "./manage.py migrate && ./manage.py runserver 0.0.0.0:8000" within my docker-compose.yml

Adiii Over a year ago

No, I mean in database connection error it should not say 127.0.0.1, how the db connection try to connect with 127.0.0.1?

Adiii Over a year ago

Verify and double check, there is some thing that override db host, it should point to container ip not to local host

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