docker-compose error connecting to redis + sidekiq

I am trying to build a container with docker but I cannot connect sidekiq + redis, the error says sidekiq_1 | Error connecting to Redis on 127.0.0.1:6379 (Errno::ECONNREFUSED), seems to sidekiq is trying to connect to localhost but since I am building "in theory" redis + sidekiq + rails + postgres containers is not in the localhost, it should be in redis image.

My docker-compose.yml file is this:

version: '3'

services:
  postgres:
    image: postgres:10.5
    volumes:
      - my_app-postgres:/var/lib/postgresql/data

  redis:
    image: redis:4.0.11
    volumes:
      - my_app-redis:/var/lib/redis/data

  web:
    build: .
    command: bundle exec rails server -p 3000 -b '0.0.0.0'
    ports:
      - '3000:3000'
    depends_on:
      - postgres
      - redis
    volumes:
      - .:/my_app
    env_file:
      - .env

  sidekiq:
    build: .
    command: bundle exec sidekiq -C config/sidekiq.yml
    volumes:
      - .:/my_app
    depends_on:
      - postgres
      - redis
    env_file:
      - .env

volumes:
  my_app-postgres:
  my_app-redis:

another interesting 'info' I see in log is Booting Sidekiq 4.2.10 with redis options {:url=>nil} this url can be the cause of the issue?

in my development environment the app is working fine, I try to 'dockerize' what I have. How could I make this work?