将带有橡胶的 Rails 应用程序部署到 AWS - nil:NilClass 错误答案

【问题标题】：deploying rails app with rubber to AWS - nil:NilClass error将带有橡胶的 Rails 应用程序部署到 AWS - nil:NilClass 错误
【发布时间】：2013-10-20 13:52:39
【问题描述】：

我第一次尝试使用 Rubber 部署到我的 AWS EC2。为了测试我现在只使用 t1.micro。

在 tcap Rubber:create_staging 之后编辑 Rubber.yml 后，我遇到了一个奇怪的橡胶错误

这是消息：

/Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/environment.rb:1:in `expand_string': undefined method `known_roles' for nil:NilClass (NoMethodError)
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/environment.rb:168:in `eval'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/environment.rb:168:in `expand_string'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/environment.rb:180:in `expand'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/environment.rb:146:in `[]'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/environment.rb:230:in `method_missing'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/rubber-2.5.5/lib/rubber/recipes/rubber/utils.rb:22:in `block (2 levels) in load'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/configuration/execution.rb:138:in `instance_eval'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/configuration/execution.rb:138:in `invoke_task_directly'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/configuration/callbacks.rb:25:in `invoke_task_directly_with_callbacks'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/configuration/execution.rb:89:in `execute_task'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/configuration/execution.rb:101:in `find_and_execute_task'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/cli/execute.rb:46:in `block in execute_requested_actions'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/cli/execute.rb:45:in `each'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/cli/execute.rb:45:in `execute_requested_actions'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/cli/help.rb:19:in `execute_requested_actions_with_help'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/cli/execute.rb:34:in `execute!'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/lib/capistrano/cli/execute.rb:14:in `execute'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/gems/capistrano-2.15.5/bin/cap:4:in `<top (required)>'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/bin/cap:23:in `load'
    from /Users/mgreschke/Dropbox/medisupply/vendor/bundle/bin/cap:23:in `<main>'

知道在哪里查找错误吗？这对我来说似乎是一个简单的问题，但我真的不知道在哪里看..

最好， M

【问题讨论】：

在您的整个应用程序中（可能在您的environment.rb）中查找关键字known_roles 调用此方法的对象返回为nil。如果您可以发布有关正在调用的对象的更多详细信息，它将对调试更有帮助。
您已经解决了这个问题吗？发布解决方案会很有帮助。
Sergey，您在下面的帖子和链接帮助解决了问题。谢谢！

标签： ruby-on-rails amazon-web-services rubber

【解决方案1】：

只需删除 rubber_env。

staging_roles: "#{known_roles.reject {|r| r =~ /slave/ || r =~ /^db$/ }.join(',')}"
# instead of
staging_roles: "#{rubber_env.known_roles.reject {|r| r =~ /slave/ || r =~ /^db$/ }.join(',')}"

有这个简单的修复https://github.com/rubber/rubber/pull/406/files。

【讨论】：

谢谢谢尔盖。这解决了解决为complete_unicorn_nginx_postgresql 模板创建的应用程序的问题