(Docker)如何在WordPress容器中使用单独的Composer容器安装依赖

Docker文件

FROM wordpress

ENV REFRESHED_AT 2015-08-12

ADD 
  composer.json /var/www/html
ADD 
  composer.lock /var/www/html

# install the PHP extensions
RUN 
  apt-get -qq update && 
  apt-get -y upgrade && 
  apt-get install -y vim wget && 
  rm -rf /var/lib/apt/lists/*

# Symlink User's "wp-content" folder into the newly installed WordPress
RUN 
  rm -rf /usr/src/wordpress/wp-content/plugins/* && 
  rm -rf /usr/src/wordpress/wp-content/themes/* && 
  cp -fr /usr/src/wordpress/* /var/www/html/ && 
  chown -R www-data:www-data /var/www/html/

# volume for mysql database and wordpress install
VOLUME ["/var/www/html/wp-content/plugins","/var/www/html/wp-content/themes"]

# Define working directory.
WORKDIR /var/www/html/

EXPOSE 80 3306

CMD ["apache2-foreground"]

Docker撰写文件

wordpress:
  build: .
  links:
    - mysql
    - composer
  volumes:
    - wp-content/plugins/:/var/www/html/wp-content/plugins
    - wp-content/themes/:/var/www/html/wp-content/themes
  environment:
    - WORDPRESS_DB_PASSWORD=__WORDPRESS_DB_PASSWORD__
    - WORDPRESS_DB_NAME=__WORDPRESS_DB_NAME__
    # - WORDPRESS_DB_USER=__WORDPRESS_DB_USER__

  ports:
    - "9888:80"

mysql:
  image: mysql:5.7
  environment:
    - MYSQL_ROOT_PASSWORD=__WORDPRESS_DB_PASSWORD__
    - MYSQL_DATABASE=__WORDPRESS_DB_NAME__

composer:
  image: composer/composer

问题详情

我可以将composer.json和composer.lock文件添加到工作目录中.我可以确认这两个文件在工作目录中.

我需要的是Dockerfile(或其他位置)也将依赖项自动安装到工作目录中.

根据Docker Hub的https://hub.docker.com/r/composer/composer/,
我应该能够docker运行-v ${pwd)：/ app composer / composer install来安装依赖项,但是我该如何在Dockerfile中做到这一点呢？

我也很困惑,因为-v标志https://docs.docker.com/engine/userguide/dockervolumes/与将指定的主机目录装入容器有关,但是我已经将必要的文件添加到了工作目录中.我要做的就是安装依赖项.

谢谢您的帮助.