Connect from Django app in a docker container to Redis in another docker container

General
1

I’ve spent the entire day trying to resolve this issue, which concerns WebSocket channels. My app works perfectly on my local environment.
First, My app works perfectly on local.
this is my docker compose

version: '3.12'

services:
  db:
    image: postgres:16
    volumes:
      - postgres_data:/var/lib/postgresql/data/
    environment:
      POSTGRES_DB: test_db
      POSTGRES_USER: postgres
      POSTGRES_PASSWORD: postgres
    ports:
      - "5432:5432"

  redis:
    image: redis:6
    container_name: redis
    ports:
      - "6379:6379"

  web:
    build:
      context: .
      dockerfile: configs/docker/dev-server/Dockerfile
    volumes:
      - .:/app
    ports:
      - "8000:8000"
    depends_on:
      - db
      - redis
    environment:
      - DATABASE_NAME=test_db
      - DATABASE_USER=postgres
      - DATABASE_PASSWORD=postgres
      - DATABASE_HOST=db
      - DATABASE_PORT=5432
      - REDIS_URL=redis://redis:6379/1
      - REDIS_HOST=redis
      - REDIS_PORT=6379

volumes:
  postgres_data:

My problem is that when I run my app on docker, I will get errors like this

OSError: [Errno 99] Cannot assign requested address
During handling of the above exception, another exception occurred:
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
redis.exceptions.ConnectionError: Error 99 connecting to localhost:6379. Cannot assign requested address.

According to my research, my app shouldn’t access to localhost, but host name. I think my settings is no problem.

print("REDIS_URL" ,getenv('REDIS_URL', 'redis://localhost:6379/1'))
CHANNEL_LAYERS = {
    "default": {
        "BACKEND": "channels_redis.core.RedisChannelLayer",
        "CONFIG": {
            'hosts': [getenv('REDIS_URL', 'redis://localhost:6379/1')],
        },
    },
}

I could see REDIS_URL redis://redis:6379/1 is logged out. so the env is successfully set.
docker network inspect shows the containers are connected properly.
“Containers”: {
“4d9f98ab4682e241d1d9e54aea60cfb0165b9eeb1b80ca76f7027e6c656951d3”: {
“Name”: “redis”,
“EndpointID”: “4985260d4ff2e193c1bcf9eadde5ea36284e13e7e4fdcb5afdbeb696d46c730e”,
“MacAddress”: “02:42:ac:1b:00:02”,
“IPv4Address”: “172.27.0.2/16”,
“IPv6Address”: “”
},
“89804ff5d2e4283049cb5a74b137f176258f3866fa40b4ed6c6b6ea8f86e6abc”: {
“Name”: “django-db-1”,
“EndpointID”: “f140a1c30bb32b47baa439e93ce12fee6887796ed2d2d1b422cc4d3b89dcaf59”,
“MacAddress”: “02:42:ac:1b:00:03”,
“IPv4Address”: “172.27.0.3/16”,
“IPv6Address”: “”
},
“979133cb3153fd62d80f467417f6eb416dd0ae07ea230cab82065c04edde8417”: {
“Name”: “django-web-1”,
“EndpointID”: “7361a78454b6d4315b0d47ce808e3316d484c9acb92d7628b64b17a7d31da985”,
“MacAddress”: “02:42:ac:1b:00:04”,
“IPv4Address”: “172.27.0.4/16”,
“IPv6Address”: “”
}
},

I could say again, When I run only db and redis on docker containers, then run my app locally, it will work. so I suppose problem come from docker network.

Thank you for your help😀

2

localhost directs a container to itself, not to the host machine

Try your host’s IP, or redis:6379

1 Like
3

Thank you for your fast reply!
I set redis url as “redis://redis:6379/1”
so my app in the docker container should access the URl redis://redis:6379/1.
but I got error saying

 Error 99 connecting to localhost:6379. Cannot assign requested address.

I don’t know why my app not using the URl redis://redis:6379/1.

4

I solve this problem!
because consumer file try to access Redis which I totally forgot.
self.redis = redis.StrictRedis(host=‘localhost’, port=6379, db=1)

Thank you for your help!

5

Awesome, glad to help :slight_smile: