ZEPPELIN-2982. Copy interpreter-setting.json to interpreter dir

[zjffdu]

What is this PR for?

2 main changes.

• Introduce interpreter-parent module, so that all the interpreter can reuse the plugin defined in interpreter-parent
• Add new plugin for copying interpreter-setting.json to interpreter dir

What type of PR is it?

[ Improvement | Refactoring]

Todos

• - Task

What is the Jira issue?

• https://issues.apache.org/jira/browse/ZEPPELIN-2982

How should this be tested?

• First time? Setup Travis CI as described on https://zeppelin.apache.org/contribution/contributions.html#continuous-integration
• Strongly recommended: add automated unit tests for any new or changed behavior
• Outline any manual steps to test the PR here.

Screenshots (if appropriate)

Questions:

• Does the licenses files need update? No
• Is there breaking changes for older versions? No
• Does this needs documentation? No

[Leemoonsoo]

Each release, interpreter jars are published in maven repository and bin/install-interpreter.sh lets user download and install interpreters. Is this change keeps capability to both publish and download interpreter jars?

[zjffdu]

Yes, it keeps capability. The interpreter jar is not changed. interpreter-setting.json is still packaged into interpreter jar, but copied to interpreter dir as well in this PR. And interpreter-setting.json under interpreter dir take precedence over that in interpreter jar. see https://github.com/apache/zeppelin/blob/master/zeppelin-zengine/src/main/java/org/apache/zeppelin/interpreter/InterpreterSettingManager.java#L263

[Leemoonsoo]

I see. Could you also explain little bit about why you decided to make interpreter-parent module instead of just add copy plugin to existing common parents zeppelin-interpreter ?

This may require some additional update

• Interpreter dev guide - which parent module should use to create new interpreter
• Interpreter list in Helium menu - Interpreter's are collected using on dependency zeppelin-interpreter. (see [ZEPPELIN-2109][2110] Sortable Helium pkgs & Introduce "INTERPRETER" type #2037)

[zjffdu]

@Leemoonsoo parent project must be pom type, but zeppelin-interpreter is jar. So I have to introduce module interpreter-parent. Interpreter dev guide is updated in the new commit.

[Leemoonsoo]

Ah, i see. I think i have confused between parent project and dependency.

[zjffdu]

will merge if no more discussion