grape_logging/lib/grape_logging/middleware/request_logger.rb

require 'grape/middleware/base'

module GrapeLogging
  module Middleware
    class RequestLogger < Grape::Middleware::Base
      def before
        env[:db_duration] = 0

        ActiveSupport::Notifications.subscribe('sql.active_record') do |*args|
          event = ActiveSupport::Notifications::Event.new(*args)
          env[:db_duration] += event.duration
        end if defined?(ActiveRecord)
      end

      def call!(env)
        original_response = nil

        duration = Benchmark.realtime { original_response = super(env) }
        logger.info parameters(original_response, duration)

        original_response
      end

      protected
        def parameters(response, duration)
          {
              path: request.path,
              params: request.params,
              method: request.request_method,
              total: (duration * 1000).round(2),
              db: request.env[:db_duration].round(2),
              status: response.first
          }
        end

      private
      def logger
        @logger ||= @options[:logger] || Logger.new(STDOUT)
      end

      def request
        @request ||= ::Rack::Request.new(env)
      end
    end
  end
end