Docker compos with redis - postgres sql

docker-compose.yml

# Use postgres/example user/password credentials
version: '3.1'

services:

  db:
    image: postgres:9.6.6
    ports: 
      - "5432:5432"
    restart: always
    environment:
      POSTGRES_PASSWORD: password           
  adminer:
    image: adminer
    restart: always
    ports:
      - 8080:8080
  
  redis:
    image: redis:3.2.11
    ports:
    - "6379:6379"