Class: ActionDispatch::RequestId

Inherits:
Object
  • Object
show all
Defined in:
actionpack/lib/action_dispatch/middleware/request_id.rb

Overview

Makes a unique request id available to the action_dispatch.request_id env variable (which is then accessible through ActionDispatch::Request#request_id or the alias ActionDispatch::Request#uuid) and sends the same id to the client via the X-Request-Id header.

The unique request id is either based on the X-Request-Id header in the request, which would typically be generated by a firewall, load balancer, or the web server, or, if this header is not available, a random uuid. If the header is accepted from the outside world, we sanitize it to a max of 255 chars and alphanumeric and dashes only.

The unique request id can be used to trace a request end-to-end and would typically end up being part of log files from multiple pieces of the stack.

Instance Method Summary collapse

Constructor Details

#initialize(app, header:) ⇒ RequestId

Returns a new instance of RequestId.


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# File 'actionpack/lib/action_dispatch/middleware/request_id.rb', line 18

def initialize(app, header:)
  @app = app
  @header = header
end

Instance Method Details

#call(env) ⇒ Object


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# File 'actionpack/lib/action_dispatch/middleware/request_id.rb', line 23

def call(env)
  req = ActionDispatch::Request.new env
  req.request_id = make_request_id(req.headers[@header])
  @app.call(env).tap { |_status, headers, _body| headers[@header] = req.request_id }
end