Pass headers through to payload for logging.

[garethson]

Summary

In attempting to log certain request headers the Rails way while still leveraging the output of ActionController::LogSubscriber's start_processing method, we realized we'd love to have the request headers in the event payload. This allows us to add header logging like this:

Started POST "/create" for 127.0.0.1 at 2016-03-09 03:14:49 +0000
Processing by RailsController#create as JSON
  Parameters: {"param_1"=>"A", "param_2"=> "B"}
  Headers: {"X-Platform-Id"=>"1", "X-Request-Id"=>"2"}
Application logic logging.
More application model logging.
Completed 200 OK in 108ms (Views: 3.1ms | ActiveRecord: 0.0ms)

via OurLogSubscriber.attach_to :action_controller.

Any other options I investigated involved completely replacing the default request logging.

@rafaelfranca

[rails-bot]

Thanks for the pull request, and welcome! The Rails team is excited to review your changes, and you should hear from @kaspth (or someone else) soon.

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[kmcphillips]

👍