[SPARK-1167] Remove metrics-ganglia from default build due to LGPL issue

• Type: Bug
• Status: Resolved
• Priority: Blocker
• Resolution: Fixed
• Affects Version/s: 0.9.0
• Fix Version/s: 0.9.1, 1.0.0
• Component/s: Spark Core
• Assignee: Patrick McFadin
• Reporter: Patrick Wendell
• Created: 02/Mar/14 20:16
• Updated: 30/Mar/14 04:13
• Resolved: 11/Mar/14 11:55

Description

The metrics ganglia code depends on an LGPL library which we can't distribute with Spark. More information can be found here:
https://groups.google.com/forum/#!searchin/metrics-user/lgpl/metrics-user/1tQd_qZHQNE/TqAfXYwh7OUJ

We should isolate this code in a separate module inside of an `/extras` folder and have a build flag in Maven/SBT (e.g. `-Pganglia`) that will pull this in if desired. That way users can still use it if they do a special build.