pass logger as option to middleware so it's easily usable when grape is mounted inside rails

lib/grape_logging/middleware/request_logger.rb

@@ -4,24 +4,25 @@ module GrapeLogging
   module Middleware
     class RequestLogger < Grape::Middleware::Base
       def before
-        @env[:db_duration] = 0
+        env[:db_duration] = 0
 
         ActiveSupport::Notifications.subscribe('sql.active_record') do |*args|
           event = ActiveSupport::Notifications::Event.new(*args)
-          @env[:db_duration] += event.duration
+          env[:db_duration] += event.duration
         end if defined?(ActiveRecord)
       end
 
       def call!(env)
         original_response = nil
-        duration = Benchmark.realtime { original_response = super(env) }
 
-        @app.logger.info parameters(::Rack::Request.new(env), original_response, duration)
+        duration = Benchmark.realtime { original_response = super(env) }
+        logger.info parameters(original_response, duration)
+
         original_response
       end
 
       protected
-        def parameters(request, response, duration)
+        def parameters(response, duration)
           {
               path: request.path,
               params: request.params,
@@ -31,6 +32,15 @@ module GrapeLogging
               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