Rubycas-client 是一个用来实现单点登陆的 gem 在 development 下需要在 application.rb 下加入如下几行

require 'casclient'
require 'casclient/frameworks/rails/filter'

CASClient::Frameworks::Rails::Filter.configure(
  cas_base_url: "http://somesite.com/cas",
  enable_single_sign_out: true
)

这样就可以调用 session[:cas_user] 来获取 CAS 登陆后的信息 在 development 下测试良好，一般来说会自动在/tmp/sessions 下生成一个 session 可是到了生产模式：

I, [2015-06-14T20:57:27.790760 #18180]  INFO -- : Filter chain halted as CASClient::Frameworks::Rails::Filter rendered or redirected
I, [2015-06-14T20:57:27.790914 #18180]  INFO -- : Completed 302 Found in 3ms (ActiveRecord: 0.0ms)
I, [2015-06-14T20:57:28.270761 #18180]  INFO -- : Started GET "/verify?user_id=MQ%3D%3D&ticket=ST-1434286982rQdTPVk-f387GBrQPqs" for 123.112.102.233 at 2015-06-14 20:57:28 +0800
I, [2015-06-14T20:57:28.273099 #18180]  INFO -- : Processing by ProfileController#verify_identity as HTML
I, [2015-06-14T20:57:28.273166 #18180]  INFO -- :   Parameters: {"user_id"=>"MQ==", "ticket"=>"ST-1434286982rQdTPVk-f387GBrQPqs"}
I, [2015-06-14T20:57:29.568797 #18180]  INFO -- : Completed 500 Internal Server Error in 1295ms
F, [2015-06-14T20:57:29.573320 #18180] FATAL -- :
Errno::ENOENT (No such file or directory - /home/mo1.0/tmp/sessions/cas_sess.ST-1434286982rQdTPVk-f387GBrQPqs):
  /usr/local/rvm/gems/ruby-2.0.0-p643/bundler/gems/rubycas-client-b6692b942f69/lib/casclient/tickets/storage.rb:101:in `initialize'
  /usr/local/rvm/gems/ruby-2.0.0-p643/bundler/gems/rubycas-client-b6692b942f69/lib/casclient/tickets/storage.rb:101:in `new'
  /usr/local/rvm/gems/ruby-2.0.0-p643/bundler/gems/rubycas-client-b6692b942f69/lib/casclient/tickets/storage.rb:101:in `store_service_session_lookup'
  /usr/local/rvm/gems/ruby-2.0.0-p643/bundler/gems/rubycas-client-b6692b942f69/lib/casclient/frameworks/rails/filter.rb:81:in `filter'
  /usr/local/rvm/gems/ruby-2.0.0-p643/bundler/gems/rubycas-client-b6692b942f69/lib/casclient/frameworks/rails/filter.rb:15:in `before'

就有了一些问题，而我自己试了试依然没能解决 以下是 production.rb 配置文件

Rails.application.configure do
  config.cache_classes = true
  config.cache_store = :redis_store, { :host => "localhost", :port => 6379, :db => 1, :namespace => "mo_production" }
  config.eager_load = false
  config.consider_all_requests_local       = false
  config.action_controller.perform_caching = true
  config.serve_static_assets = true
  config.assets.debug = true
  config.assets.compile = true
  config.assets.digest = true
  config.assets.version = '1.0'
   config.action_dispatch.x_sendfile_header = 'X-Accel-Redirect' # for nginx
  config.log_level = :info
  config.assets.precompile += %w(mediaelementplayer.js mediaelementplayer.css home.js waterfall.js)
  config.i18n.fallbacks = true
  config.active_support.deprecation = :notify
  config.log_formatter = ::Logger::Formatter.new
  config.active_record.dump_schema_after_migration = false
end

求帮助 QUQ

解决方法：

chmod -R u+rwX,go+rX,go-w /tmp
chmod -R u+rwX,go+rX,go-w /home/yourapp/tmp
mkdir /home/yourapp/tmp/sessions

生产模式下没有自动生成 sessions 文件夹，这可能是问题之一 还有读写权限问题，这是问题之二 感谢@billy的热心帮助