title: hadoop yarn: unknown user and group
body: <p>I'm trying to figure out why my MR jobs are failing. One of the doubts I have is this warning in yarn resourcemanager's log: </p>
  
  <pre><code>2015-08-14 12:00:45,610 INFO SecurityLogger.org.apache.hadoop.ipc.Server: Auth successful for testing (auth:SIMPLE)
  2015-08-14 12:00:45,624 WARN org.apache.hadoop.security.ShellBasedUnixGroupsMapping: got exception trying to get groups for user testing: id: testing: No such user
  
  2015-08-14 12:00:45,624 WARN org.apache.hadoop.security.UserGroupInformation: No groups available for user testing
  2015-08-14 12:00:45,624 INFO SecurityLogger.org.apache.hadoop.security.authorize.ServiceAuthorizationManager: Authorization successful for testing (auth:TOKEN) for protocol=interface org.apache.hadoop.yarn.s
  erver.nodemanager.api.LocalizationProtocolPB
  </code></pre>
  
  <p>I don't have user '<strong>testing</strong>' configured anywhere. Also I couldn't find it mentioned in default configuration of yarn, mapreduce or other hadoop's subsystem.</p>
  
  <p>Does anyone know where did this user come from?</p>