Hadoop中的dr.who是什么

Hadoop中的dr.who是什么？

1.问题

今天在查看自己的hadoop web ui的时候，发现了如下的界面：

仔细看右上角，发现这里登陆的用户名是：dr.who，这个dr.who是谁呢？难道是别黑客入侵了？【一般不可能是黑客入侵，难道我自己的虚拟机集群都值钱？】

2.原因

下面这句话引自《Hadoop权威指南》的chapter 6 中的Setting Up the Development Environment 的 Managing Configuration。

The user identity that Hadoop uses for permissions in HDFS is determined by running the whoami command on the client system. Similarly, the group names are derived from the output of running groups.
If, however, your Hadoop user identity is different from the name of your user account on your client machine, you can explicitly set your Hadoop username by setting the HADOOP_USER_NAME environment variable. You can also override user group mappings by means of the hadoop.user.group.static.mapping.overrides configuration property. For example, dr.who=;preston=directors,inventors means that the dr.who user is in no groups, but preston is in the directors and inventors groups.
You can set the user identity that the Hadoop web interfaces run as by setting the hadoop.http.staticuser.user property. By default, it is dr.who, which is not a superuser, so system files are not accessible through the web interface.

主要关注下面这句话：
By default, it is dr.who,which is not a superuser, so system files are not accessible through the web interface.
默认情况下，它是dr.who，这不是一个超级用户，所以通过web 界面，系统文件是不可以被访问的。