[CONFIGURATION-522] support specify config items through system property

• Type: Improvement
• Status: Closed
• Priority: Minor
• Resolution: Invalid
• Affects Version/s: 2.x
• Fix Version/s: 2.x
• Component/s: Interpolation
• Labels: configuration property system
• Assignee: Unassigned
• Reporter: Zesheng Wu
• Created: 18/Jan/13 06:35
• Updated: 18/Jan/13 08:28
• Resolved: 18/Jan/13 08:28

Description

The current hadoop config items are mainly interpolated from the *-site.xml files. In our production environment, we need a mechanism that can specify config items through system properties, which is something like the gflags for system built with C++, it's really very handy.
The main purpose of this patch is to improve the convenience of hadoop systems, especially when people do testing or perf tuning, which always need to modify the *-site.xml files
If this patch is applied, then people can start hadoop programs in this way: java -cp $class_path -Dhadoop.property.$name=$value $program