Adding redis to the composition

docker-compose.yml

version: '2'
services:
  database:
    image: postgres
    volumes:
      - ./data/pgdata:/pgdata
    env_file:
      - '.env'
  web:
    links:
      - database
      - redis
    build: .
    volumes:
      - .:/opt/fooapp
    ports:
      - '3000:3000'
    command: [bundle, exec, puma]
    env_file:
      - '.env'
  redis:
    image: 'redis:3.2-alpine'
    command: redis-server
    ports:
      - '6379:6379'
    volumes:
      - './data/redisdata:/var/lib/redis/data'