[AMBARI-12763] Adding Support for WebHDFS HA mode in Knox Configuration

• Type: Improvement
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 2.1.0
• Fix Version/s: 2.3.0
• Component/s: ambari-server
• Assignee: Zachary Blanco
• Reporter: Zachary Blanco
• Created: 13/Aug/15 15:20
• Updated: 20/Aug/15 14:05
• Resolved: 19/Aug/15 22:24

Description

In the Apache Knox service screen > configuration > advanced topology the templating/macros used does automatically add multiple namenode URLs if WebHDFS HA is enabled.

We should changed the template from

<url>http://{{namenode_host}:{{namenode_port}}webhdfs</url>

to something that's simple like:

webhdfs_service_urls

This will automatically add URLs if there are multiple namenodes - thus allowing one less step for setting up HA for WebHDFS in Knox

So for example, if we have a cluster running in HA mode, previously the old templating feature would have looked something like this:

<service>
  <role>WEBHDFS</role>
  <url>http://{{namenode_host}}:{{namenode_port}}/webhdfs</url>
</service>

and written the following the disk for the WebHDFS service:

<service>
  <role>WEBHDFS</role>
  <url>http://namenode_host_1:namenode_port/webhdfs</url>
</service>

Even though the cluster is running in HA mode, only 1 url would have been written. Now with this new feature we could replace the old

http://{{namenode_host}}:{{namenode_port}}/webhdfs

with

{{webhdfs_service_urls}}

and the urls for each server running namenode would be put into their place. Thus making the XML written to disk the following:

<service>
  <role>WEBHDFS</role>
  <url>http://namenode_host_1:namenode_port/webhdfs</url>
  <url>http://namenode_host_2:namenode_port/webhdfs</url>
  <url>http://namenode_host_3:namenode_port/webhdfs</url>
</service>