[HDDS-658] Implement s3 bucket list backend call and use it from rest endpoint

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.4.0
• Component/s: S3
• Target Version/s: 0.4.0
• Assignee: Bharat Viswanadham
• Reporter: Marton Elek
• Created: 15/Oct/18 12:26
• Updated: 16/Nov/18 01:30
• Resolved: 15/Nov/18 14:23

Description

HDDS-657 provides a very basic functionality for list buckets. There are two problems there:

1. It repeats the username -> volume name mapping convention.
2. Doesn't work if volume doesn't exist (no s3 buckets created, yet).

The proper solution is to do the same on server side:

1. Use the existing naming convention in OM
2. Return empty list in case of value is missing.

It requires an additional rpc call to the om.