为什么aws-sdk-ruby在初始化时连接到'169.254.169.254'？
问题描述：
我安装了gem webmock，它在测试套件中*了外部连接。安装完成后，运行测试套件时出现意外的结果。为什么aws-sdk-ruby在初始化时连接到'169.254.169.254'？
我有点困惑为什么aws-sdk需要在初始化时连接到169.254.169.254？
rspec spec/models/concerns/posconcern_spec.rb
[Coveralls] Set up the SimpleCov formatter.
[Coveralls] Using SimpleCov's 'rails' settings.
An error occurred while loading ./spec/models/concerns/posconcern_spec.rb.
Failure/Error: require File.expand_path('../../config/environment', __FILE__)
WebMock::NetConnectNotAllowedError:
Real HTTP connections are disabled. Unregistered request: GET http://169.254.169.254/latest/meta-data/iam/security-credentials/ with headers {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'User-Agent'=>'Ruby'}
You can stub this request with the following snippet:
stub_request(:get, "http://169.254.169.254/latest/meta-data/iam/security-credentials/").
with(headers: {'Accept'=>'*/*', 'Accept-Encoding'=>'gzip;q=1.0,deflate;q=0.6,identity;q=0.3', 'User-Agent'=>'Ruby'}).
to_return(status: 200, body: "", headers: {})
============================================================
# /home/andey/.rvm/gems/ruby-2.3.4/gems/webmock-3.1.0/lib/webmock/http_lib_adapters/net_http.rb:114:in `request'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:109:in `http_get'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:90:in `block (2 levels) in get_credentials'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:105:in `open_connection'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:88:in `block in get_credentials'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:121:in `retry_errors'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:87:in `get_credentials'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:73:in `block in refresh'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:121:in `retry_errors'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:72:in `refresh'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/refreshing_credentials.rb:20:in `initialize'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/instance_profile_credentials.rb:51:in `initialize'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/credential_provider_chain.rb:90:in `new'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/credential_provider_chain.rb:90:in `instance_profile_credentials'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/credential_provider_chain.rb:12:in `block in resolve'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/credential_provider_chain.rb:11:in `each'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/credential_provider_chain.rb:11:in `resolve'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/aws-sdk-core/plugins/request_signer.rb:37:in `block in <class:RequestSigner>'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:70:in `call'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:205:in `block in resolve_defaults'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:57:in `each'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:57:in `each'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:204:in `resolve_defaults'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:200:in `value_at'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:189:in `block in resolve'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:189:in `resolve'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:177:in `apply_defaults'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/configuration.rb:150:in `build!'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/base.rb:68:in `build_config'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/base.rb:19:in `initialize'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/aws-sdk-core-2.10.52/lib/seahorse/client/base.rb:105:in `new'
# ./config/initializers/aws.rb:1:in `<top (required)>'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:268:in `load'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:268:in `block in load'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:240:in `load_dependency'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/activesupport-4.2.9/lib/active_support/dependencies.rb:268:in `load'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/engine.rb:652:in `block in load_config_initializer'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/activesupport-4.2.9/lib/active_support/notifications.rb:166:in `instrument'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/engine.rb:651:in `load_config_initializer'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/engine.rb:616:in `block (2 levels) in <class:Engine>'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/engine.rb:615:in `each'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/engine.rb:615:in `block in <class:Engine>'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/initializable.rb:30:in `instance_exec'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/initializable.rb:30:in `run'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/initializable.rb:55:in `block in run_initializers'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/initializable.rb:44:in `each'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/initializable.rb:44:in `tsort_each_child'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/initializable.rb:54:in `run_initializers'
# /home/andey/.rvm/gems/ruby-2.3.4/gems/railties-4.2.9/lib/rails/application.rb:352:in `initialize!'
# ./config/environment.rb:5:in `<top (required)>'
# ./spec/rails_helper.rb:3:in `require'
# ./spec/rails_helper.rb:3:in `<top (required)>'
# ./spec/models/concerns/posconcern_spec.rb:1:in `require'
# ./spec/models/concerns/posconcern_spec.rb:1:in `<top (required)>'
相关链接回购：
答
它试图连接到AWS元数据服务器来获取AWS凭据。所有AWS服务器都应该能够连接到内部元数据服务器。
我在 测试套件
你是如何阻止它安装宝石webmock，阻断外部连接？防火墙吗？添加规则以允许流量到169.254.169.254或存根。
脚本正在尝试连接到AWS服务。为此，它需要以多种方式提供的证书。一种方法是使用AWS IAM角色并从元数据服务器（169.254.169.254）动态获取凭证。您的脚本连接到169.254.169.254以获取凭证。它可以用于稍后连接到AWS服务。
答
这是@helloV的答案的后续。
上
http://169.254.169.254/latest/meta-data/iam/security-credentials/
对实例的应用程序的完整文档检索从实例元数据项 IAM /安全证书/角色名称的角色提供的安全证书 。通过与该角色关联的安全证书，该应用程序被授予对您为 角色定义的操作和资源的 权限。这些 安全凭证是临时的，我们会自动对其进行旋转。 我们在 旧凭证到期前至少五分钟提供新的凭据。
我从不同的角度观看的问题。为什么它应该在我的测试套件中运行？如何防止aws-sdk做到这一点？我的测试套件不需要连接到互联网。 –
你知道aws sdk在没有互联网的情况下什么都不做？ –
@AndrewWei你需要嘲笑元数据服务器的连接。 – helloV