[AMBARI-14966] Stack Advisor incorrectly recommends Slave component on a host which does not have it installed during Add service wizard

• Type: Bug
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Affects Version/s: trunk
• Fix Version/s: 2.2.0
• Component/s: stacks
• Assignee: Bhuvnesh Chaudhary
• Reporter: Bhuvnesh Chaudhary
• Created: 09/Feb/16 02:06
• Updated: 14/Jul/16 18:15
• Resolved: 12/Feb/16 01:06

Description

Steps to reproduce:

• Install a cluster with HDFS (To start with single node host c6401)
  FreshInstallOnSingleNode.png
• Add a new host (c6402) and don't add any of the slave components or client
  AddHostWithoutAnyService.png
• Add HAWQ or any other service, don't change the recommendation on master components page and click next
• Datanode checkbox will be checked on c6402 even though its not installed.
  IncorrectAssignment.png

Bug:

• Datanode should not be checked on c6402 as its not installed on the host.

Current Behavior:

• In stack advisor, a list of free hosts is created at https://github.com/apache/ambari/blob/trunk/ambari-server/src/main/resources/stacks/stack_advisor.py#L382
• During the step of creating the recommendation for Slave components slave hosts map is extended with any of the hosts in the freeHosts list at https://github.com/apache/ambari/blob/trunk/ambari-server/src/main/resources/stacks/stack_advisor.py#L412-L413
• Then in Ambari-web it updates the checkbox or datanode as installed on c6402.

Since this minor code changes goes to core stack advisor, i am requesting inputs to be sure before going ahead with the change.

Few questions:
1. Do we extend the hostlist for already installed Slaves for some reason or its incorrect ?
2. Do you foresee any concerns with the patch. (I have tested it on Fresh Install of Cluster and Add services page)

After fix: Datanode is not checked on c6402
AfterFix.png

Issue Links

• links to: Review board