Compose: 链接不适用于Dockerfile中的rake

目前，我正在使用docker compose将我的Web应用程序与postgre数据库连接。 我的配置如下所示：

# Dockerfile

FROM rails:onbuild
RUN rake db:create db:migrate db:seed

# config/database.yml

# SQLite version 3.x
#   gem install sqlite3
#
#   Ensure the SQLite 3 gem is defined in your Gemfile
#   gem 'sqlite3'
#
default: &default
    adapter: postgresql
    encoding: utf8
    database: rezeptr_prod
    pool: 5
    username: postgres
    password:
    host: db

development:
  <<: *default
  database: rezeptr_dev

# Warning: The database defined as "test" will be erased and
# re-generated from your development database when you run "rake".
# Do not set this db to the same as development or production.
test:
  <<: *default
  database: rezeptr_test

# docker-compose.yml

db:
  image: postgres
web:
  build: .
  volumes:
    - .:/usr/src/app
  ports:
    - "3000:3000"
  links:
    - db:db

如果我运行docker-compose up我会收到此错误

could not translate host name "db" to address: Name or service not known

如果我没有在Dockerfile中运行rake db:create ...并像这样docker-compose run web rake db:create一样运行它，它将正常工作，并且我不会收到任何错误。 你能帮助我吗？