[YARN-5177] Make Node-Manager Download-Resource Component extensible.

• Type: Improvement
• Status: Patch Available
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 2.7.0
• Component/s: nodemanager
• Labels: oct16-medium
• Target Version/s: 2.7.0
• Assignee: Emeka-NMC
• Reporter: Emeka-NMC
• Created: 28/May/16 00:34
• Updated: 27/Oct/16 19:40

Description

Problem:

• Downloading files to a local machine/node is called "resource-localization".
• There are two components that perform resource-location (PublicLocalizer and ComponetLocalizers)
• Both components utilizes FSDownload.class to perform their downloads.
• We need a custom implementation of FSDownload.

Solution:

• With this change, we make FSDownload.class extensible by wrapping it in a new ResourceDownloader.interface
• We also update the PublicLocalizer and ComponetLocalizers to load ResourceDownloader rather than FSDownload.
• NOTE: We use reflection to load the right implementation during runtime.