[HDDS-3101] Depend on lightweight ConfigurationSource interface instead of Hadoop Configuration

• Type: Sub-task
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.0.0
• Labels: pull-request-available
• Target Version/s: 1.0.0
• Assignee: Marton Elek
• Reporter: Marton Elek
• Created: 28/Feb/20 08:49
• Updated: 24/Apr/20 22:07
• Resolved: 21/Apr/20 08:34

Description

To make it possible to create different client jars compiled with different version of Hadoop we need clear and Hadoop independent hdds-common (and hdds-client) projects.

(For more details about the motivation, check this design doc: https://lists.apache.org/thread.html/rd0ea00f958368e888db1947eb71e514fb977df0b7baaad928ac50e94%40%3Cozone-dev.hadoop.apache.org%3E)

Our current blocker is the usage of `org.apache.hadoop.conf.Configuration`. Configuration class is a heavyweight object from hadoop-common which introduce a lot of unnecessary dependencies. It also violates multiple OOP principles, for example the Dependency inversion principle.

To make our components more independent I propose to depend on a lightweight ConfigurationSource interface which includes all the required getXXX methods. OzoneConfiguration can implement that interface (and with older Hadoop we can create direct adapters).