Class: Rack::Instruments

Inherits:
Object
  • Object
show all
Defined in:
lib/rack/instruments.rb

Constant Summary collapse

UUID_PATTERN = 
/\A([a-f0-9]{8}-[a-f0-9]{4}-4[a-f0-9]{3}-[89ab][a-f0-9]{3}-[a-f0-9]{12}|[a-f0-9]{32})\Z/

Instance Method Summary collapse

Constructor Details

#initialize(app, options = {}) ⇒ Instruments

Returns a new instance of Instruments.



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# File 'lib/rack/instruments.rb', line 9

def initialize(app, options={})
  @app = app

  @context              = options[:context]
  @header_request_ids   = options.fetch(:header_request_ids, true)
  @heroku_request_id    = options.fetch(:heroku_request_id, true)
  @ignore_extensions    = options.fetch(:ignore_extensions,
    %w{css gif ico jpg js jpeg pdf png})
  @request_id_generator = options.fetch(:request_id_generator,
    lambda { SecureRandom.uuid })
  @request_id_pattern   = options.fetch(:request_id_pattern, UUID_PATTERN)
  @response_request_id  = options.fetch(:response_request_id, false)
end

Instance Method Details

#call(env) ⇒ Object 



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# File 'lib/rack/instruments.rb', line 23

def call(env)
  return @app.call(env) \
    if @ignore_extensions && @ignore_extensions.any? { |ext|
      env["REQUEST_PATH"] =~ /\.#{ext}$/
    }

  request_ids = [current_request_id(env)]
  status, headers, response = nil, nil, nil

  # make ID of the request accessible to consumers down the stack
  env["REQUEST_ID"] = request_ids[0]

  # Extract request IDs from incoming headers as well. Can be used for
  # identifying a request across a number of components in SOA.
  if @header_request_ids
    request_ids += extract_request_ids(env)
    env["REQUEST_IDS"] = request_ids.join(",")
  end

  data = {
    method:     env["REQUEST_METHOD"],
    path:       env["REQUEST_PATH"],
    ip:         env["HTTP_X_FORWARDED_FOR"] || env["REMOTE_ADDR"],
    request_id: request_ids.join(","),
    status:     lambda { status },
  }
  data.merge!(@context) if @context

  Slides.log(:instrumentation, data) do
    status, headers, response = @app.call(env)
  end

  # optionally, inject a request ID into the reponse headers
  if @response_request_id
    headers["Request-Id"] = request_ids[0]
  end

  [status, headers, response]
end