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?

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

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)

@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.

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

will merge if no more discussion