Grape Log Instrumentation

grape_log_request_subscriber.rb

class GrapeRequestLogSubscriber < ActiveSupport::LogSubscriber

  def grape_controller(event)
    request = Rack::Request.new(event.payload).env
    response = Rack::Response.new(event.payload)
    data      = extract_request(request)
    data.merge! extract_status(response)
    logger.send(:warning, data.to_json)
  end

  private

  def extract_request(payload)
    request = payload[:request]
    {
      :method => request['REQUEST_METHOD'],
      :path => request['PATH_INFO'],
      :format => extract_format(request)
    }
  end

  def extract_format(request)
    request['PATH_INFO'].split('.').last
  end

  def extract_status(payload)
    { status: payload.status.to_i }
  end
end

grape_notification_instrumentation.rb

require 'grape'

module Lograge
  module Instrumentation
    class Grape < ::Grape::Middleware::Base
      def call!(env)
        ActiveSupport::Notifications.instrument('grape_controller', request: env) do
          @env = env
          before
          @app_response = @app.call(@env)
          after || @app_response
        end
      end

    end
  end
end

ActiveSupport::Notifications.subscribe('grape_controller', GrapeRequestLogSubscriber.new)