Docker compose - Name or service not known when calling service from another container

Question

I have a Django app in one container, trying to compose it with Redis and Mysql containers. However, calling

redis://redis:6379

from Django app, gives me

ConnectionError: Error -2 connecting redis://redis:6379. Name or service not known.

I do not see any difference in my setup, compare to other working solutions. Do I miss something? My docker-compose.yml

version: '3'

services:
  web:
    build: .
    environment:
      - REDIS_HOST=redis
    restart: always
    command: bash -c "python manage.py runserver --settings=settings.production_cs 0.0.0.0:8000"
    container_name: eprofi
    volumes:
      - .:/eprofi
    ports:
      - "8000:8000"
    depends_on:
      - db
      - redis
    links:
      - db:postgres
      - redis:redis
  db:
    image: mysql:latest
    command: mysqld --default-authentication-plugin=mysql_native_password
    volumes:
      - "./mysql:/var/lib/mysql"
    ports:
      - "3306:3306"
    restart: always
    environment:
      - MYSQL_ROOT_PASSWORD=secret123
      - MYSQL_DATABASE=django_app
      - MYSQL_USER=django_app
      - MYSQL_PASSWORD=django_app123
  redis:
    restart: always
    image: redis:latest
    ports:
      - "6379:6379"

My Dockerfile

# We Use an official Python runtime as a parent image
FROM python:2.7.13
ENV DEBIAN_FRONTEND noninteractive

ENV PYTHONDONTWRITEBYTECODE 1
# The enviroment variable ensures that the python output is set straight
# to the terminal with out buffering it first
ENV PYTHONUNBUFFERED 1

# create root directory for our project in the container
RUN mkdir /www

# Set the working directory to /www
WORKDIR /www

#Upgrade pip
RUN pip install pip -U

#Install dependencies
ADD requirements.txt /www/
RUN pip install -r requirements.txt --src /usr/local/src

# Copy the current directory contents into the container at /www
ADD . /www/

Then I do

docker-compose build
docker-compose up

Everything starts as expected, but calling Redis with "redis://redis:6379" gives the above "Name or service not known." error.

My tools

docker-compose version 1.17.1, build unknown
docker-py version: 2.5.1
Client: Docker Engine - Community
 Version:           19.03.4

UPDATE 1 How I call Redis from python app (old Django).

Settings of Django app:

CACHES = {
    'my_cache': {
        'BACKEND': 'redis_cache.RedisCache',
        'LOCATION': 'redis://{}:{}'.format(REDIS_HOST, REDIS_PORT),
        'KEY_PREFIX': 'project/my_cache',
        'TIMEOUT': 60*60*24,  # expire in 24 hours
        'OPTIONS': {
            'DB': 1,
            'PARSER_CLASS': 'redis.connection.HiredisParser'
        }
    },
}

Call:

cache = get_cache('my_cache')
cache.get(cache_key)

UPDATE 2

Command

ping redis

run in the container gives me an error

ping: unknown host

user_1226018 · Answer

I've had a similar issue with the V2 release of Docker Compose introduced in Docker Desktop. For now, simply unchecking the option solves the problem in my case. Not sure if this is because links are going to be deprecated in docker-compose or not, it seems that the doc still lists the command without deprecation warning.

user_3763848 · Answer

The links option is deprecated according to the documentation. In order the services to call each other, they should be on the same network. So for your example the solution is something like this. You can learn more about network here.

version: '3'

services:
  web:
    ...
    networks:
      - my_network
  db:
    ...
    networks:
      - my_network
  redis:
    ...
    networks:
      - my_network

networks:
  my_network:
    external:
      name: my_network

Docker compose - Name or service not known when calling service from another container

2 Answers