ruby-on-rails - 在 Ruby on Rails 中执行每个 Controller 后获取响应状态

Question

我有一个 RoR Rest API，我想发出一个指标，其中包含我的 API 的每个响应的状态。除了 Controller 崩溃的情况外，我设法对所有情况都做到了这一点。

例如在 ApplicationController 中使用以下代码:

require 'statsd-ruby'

class ApplicationController < ActionController::API
  after_action :push_status_metric

  def push_status_metric
    statsd = Statsd.new ENV['STATSD_LOCATION'], ENV['STATSD_PORT']
    puts normalize_status_metric(response.status)

    statsd.increment('ds.status.' + normalize_status_metric(response.status).to_s + '.int') unless request.fullpath == '/health'
  end

  private

  def normalize_status_metric(status)
    return 100 if status >= 100 && status < 200
    return 200 if status >= 200 && status < 300
    return 300 if status >= 300 && status < 400
    return 400 if status >= 400 && status < 500
    return 500 if status >= 500 && status < 600
    0
  end
end

但是这个解决方案不会捕获诸如 ActionController::RoutingError 和 ActiveRecord::RecordNotFound 之类的错误。

我尝试了以下代码:

  rescue_from StandardError do |exception|
    statsd = Statsd.new ENV['STATSD_LOCATION'], ENV['STATSD_PORT']
    statsd.increment('ds.status.' + normalize_status_metric(response.status).to_s + '.int') unless request.fullpath == '/health'

    raise exception
  end

但是当执行此回调时，response.status 值始终为 200(似乎到目前为止框架尚未设置)。

Answer 1

知道 rails 记录器设法做到这一点，我们可以看看它的类，ActionController::LogSubscriber和 process_action 方法。因此，该事件中的状态可能是 nil，如果存在异常，我们可以看到他们如何将异常转换为状态:

status = payload[:status]
if status.nil? && payload[:exception].present?
  exception_class_name = payload[:exception].first
  status = ActionDispatch::ExceptionWrapper.status_code_for_exception(exception_class_name)
end

所以现在，我们可以通过自己订阅这个事件来做类似的事情，用 Active Support Instrumentation ，通过创建一个初始值设定项:

ActiveSupport::Notifications.subscribe 'process_action.action_controller' do |*args|
  event = ActiveSupport::Notifications::Event.new(*args)

  # opening a file here is probably a performance nightmare, but you'd be doing something with statsd, not a file, anyway
  open('metrics.txt', 'a') do |f|
    # get the action status, this code is from the ActionController::LogSubscriber
    status = event.payload[:status]

    if status.nil? && event.payload[:exception].present?
      exception_class_name = event.payload[:exception].first

      status = ActionDispatch::ExceptionWrapper.status_code_for_exception(exception_class_name)
    end

    f.puts "process_action.action_controller controller: #{event.payload[:controller]} - action: #{event.payload[:action]} - path: #{event.payload[:path]} - status: #{status}"
  end
end

然后用一个简单的 Controller 点击几次:

class HomeController < ApplicationController
  def non_standard_status
    render html: 'This is not fine', status: :forbidden
  end

  def error
    raise ActiveRecord::RecordNotFound, 'No Records Found'
  end

  def another_error
    raise ArgumentError, 'Some Argument is wrong'
  end

  def this_is_fine
    render html: 'This is fine'
  end
end

产生一个文件:

process_action.action_controller controller: HomeController - action: non_standard_status - path: /forbidden - status: 403
process_action.action_controller controller: HomeController - action: error - path: /error - status: 404
process_action.action_controller controller: HomeController - action: another_error - path: /error2 - status: 500
process_action.action_controller controller: HomeController - action: this_is_fine - path: /fine - status: 200