ruby-on-rails-4 – Docker rails 4：,奇怪的错误：RUN bundle e

FROM ubuntu:14.04

RUN apt-get update && 
    apt-get install -qy software-properties-common

RUN apt-add-repository -y ppa:brightbox/ruby-ng
RUN apt-get update && apt-get upgrade -y

# Ruby and dependencies
RUN apt-get install -qy curl nodejs libmysqlclient-dev libsqlite3-dev libpq-dev build-essential 
                        ruby2.2 ruby2.2-dev
RUN gem install bundler --no-ri --no-rdoc

# Cache bundle install
WORKDIR /tmp
ADD Gemfile Gemfile
ADD Gemfile.lock Gemfile.lock
RUN bundle install --without development test

# Add rails project to project directory
ADD ./ /rails

# set WORKDIR
WORKDIR /rails

RUN bundle exec rake assets:precompile

# Cleanup
RUN apt-get clean && rm -rf /var/lib/apt/lists/* /tmp/* /var/tmp/*

# Publish port 8080
EXPOSE 8080

在我的docker-compose.ml中,我的服务定义为使用此Dockerfile构建它

....
web:
  build: .
  ....

但是构建失败了：

service 'web' failed to build: The command '/bin/sh -c bundle exec rake assets:precompile' returned a non-zero code: 1

根据控制台,错误是：

---> Running in 32c12f52e507
/var/lib/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/spec_set.rb:92:in 
`block in materialize': Could not find debug_inspector-0.0.2 in any of 
the sources (Bundler::GemNotFound)

我在Gemfile中添加了gem,

gem 'debug_inspector','~> 0.0.2'

我将它捆绑并重建..现在又为另一个丢失的gem引发了另一个错误：

var/lib/gems/2.2.0/gems/bundler-1.10.6/lib/bundler/spec_set.rb:92:in 
`block in materialize': Could not find binding_of_caller-0.7.2 in any
 of the sources (Bundler::GemNotFound)

我不明白发生了什么……我忘了避免这种重复错误的原因是什么？

感谢帮助