Ruby on rails 独角兽，罐头'；t重新启动："；rack and rack:：Builder必须可用于处理config.ru“；

我有一个带有nginx和unicorn的Ubuntu 14.04服务器。我已经将一个带有capistrano的Rails应用程序部署到

/home/Rails/myapp

当尝试使用

sudo service unicorn restart

重新启动unicorn时，我得到以下信息：

* Restarting Unicorn web server unicorn
rack not available, functionality reduced
rack and Rack::Builder must be available for processing config.ru

当我尝试在浏览器中访问该站点时，我从nginx获得502

这是我的/etc/default/unicorn文件：

# Change paramentres below to appropriate values and set CONFIGURED to yes.
CONFIGURED=yes

# Default timeout until child process is killed during server upgrade,
# it has *no* relation to option "timeout" in server's config.rb.
TIMEOUT=60

# Path to your web application, sh'ld be also set in server's config.rb,
# option "working_directory". Rack's config.ru is located here.
APP_ROOT=/home/rails/myapp/current

# Server's config.rb, it's not a rack's config.ru
CONFIG_RB=/etc/unicorn.conf

# Where to store PID, sh'ld be also set in server's config.rb, option "pid".
PID=/home/rails/myapp/current/pids/unicorn.pid
RAILS_ENV="production"
UNICORN_OPTS="-D -c $CONFIG_RB -E $RAILS_ENV"

PATH=/usr/local/rvm/rubies/ruby-2.3.0/bin:/usr/local/sbin:/usr/bin:/bin:/sbin:/usr/local/rvm/bin:/usr/local/rvm/gems/ruby-2.3.0@global/bin:/usr/local/rvm/gems/ruby-2.3.0/bin/
export GEM_HOME=/usr/local/rvm/gems/ruby-2.3.0
export GEM_PATH=/usr/local/rvm/gems/ruby-2.3.0:/usr/local/rvm/gems/ruby-2.3.0@global
DAEMON=/usr/local/rvm/gems/ruby-2.3.0/wrappers/unicorn

这是我的/etc/unicorn.conf文件：

listen "unix:/var/run/unicorn.sock"
worker_processes 4
user "rails"
working_directory "/home/rails/myapp/current"
pid "/var/run/unicorn.pid"
stderr_path "/var/log/unicorn/unicorn.log"
stdout_path "/var/log/unicorn/unicorn.log"

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有什么想法吗？我觉得我什么都试过了。

在启动unicorn之前，试着运行以下命令：

gem install rack

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如果您的RUBY版本是

gem install rubygems-update
update_rubygems