Where are MapReduce logs when your using yarn framework

For last couple of months i have been using Yarn framework for running my mapreduce jobs. Normally using Yarn is transparent so i did not have to do any thing different but just change my mapred-site.xml file to set value of mapreduce.framework.name to yarn like this.

	<?xml version="1.0"?>
	<?xml-stylesheet type="text/xsl" href="configuration.xsl"?>
	<!--
	Licensed under the Apache License, Version 2.0 (the "License");
	you may not use this file except in compliance with the License.
	You may obtain a copy of the License at
	http://www.apache.org/licenses/LICENSE-2.0
	Unless required by applicable law or agreed to in writing, software
	distributed under the License is distributed on an "AS IS" BASIS,
	WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	See the License for the specific language governing permissions and
	limitations under the License. See accompanying LICENSE file.
	-->
	<!-- Put site-specific property overrides in this file. -->
	<configuration>
	<property>
	<name>mapreduce.framework.name</name>
	<value>yarn</value>
	</property>
	</configuration>

view raw mapred-site.xml hosted with ❤ by GitHub

But YARN affects how the logs and job history gets stored. For example if your using traditional map reduce framework you can go to http://localhost:50030 to look at the job and task history and also access the logs generated by mapreduce framework. In case of Yarn you will have to go to http://localhost:8088/cluster and it will take you to Resource Manager Home page like this, there you should see list of applications and then click on the name of the application and to get more details

When you try to look at the logs for application, it takes you the nodemanager home page like this

Since i am working on single node cluster i like to go to the hadoop log directory and there under userlogs directory i can see log folders for each application. The application folder is subdivided into container folder one for mapper task one for reducer task and one for driver task and each of the container folders has one file for stdout, stderr and syslog that contains more output. If you have any System.out.println() in your mapper or reducer class you should find the appropriate container folder and stdout file in that container should have output that you generated using System.out.println()