[HADOOP-15005] Support meta tag element in Hadoop XML configurations

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 3.1.0
• Hadoop Flags: Reviewed
• Assignee: Ajay Kumar Assign to me
• Reporter: Ajay Kumar
• Created: 24/Aug/17 18:59
• Updated: 01/Nov/17 16:30
• Resolved: 07/Sep/17 20:46

Description

We should tag the hadoop/hdfs config so that we can retrieve properties by there usage/application like PERFORMANCE, NAMENODE etc. Right now we don't have an option available to group or list related properties together. Grouping properties through some restricted set of Meta tags and then exposing them in Configuration class will be useful for end users.
For example, here is an config file with tags.

<configuration>
   <property>
      <name>dfs.namenode.servicerpc-bind-host</name>
      <value>localhost</value>
      <tag> REQUIRED </tag>
   </property>
   
  <property>
      <name>dfs.namenode.fs-limits.min-block-size</name>
      <value> 1048576 </value>
      <tag> PERFORMANCE,REQUIRED</tag>
   </property>

 <property>
      <name>dfs.namenode.logging.level</name>
      <value>Info</value>
      <tag>HDFS, DEBUG </tag>
   </property>
      
<configuration>

Issue Links

• is related to: HDFS-12529 Get source for config tags from file name
• is related to: HADOOP-15007 Stabilize and document Configuration <tag> element