ZEPPELIN-3246. Need option for automatically restart the livy interpreter automatically as zeppelin does not start new Livy session if yarn livy session application is killed

[zjffdu]

What is this PR for?

Add one new property zeppelin.livy.restart_dead_session to allow livy session to be created automatically. By default it is false, because there's many reason that session is dead, it is encouraged to ask user to check why it is dead and restart interpreter by themselves.

What type of PR is it?

[Feature]

Todos

• - Task

What is the Jira issue?

• https://issues.apache.org/jira/browse/ZEPPELIN-3246

How should this be tested?

• Manually tested.

Screenshots (if appropriate)

Questions:

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

[bikassaha]

Can this be specified on a per notebook basis using the %conf interpreter? It may be difficult to turn this on globally because of the various reasons why sessions may die.

Would it be better for the error message to ask the user to restart the interpreter from the notebook page itself?

[zjffdu]

For whatever interpreter setting, user can set it via %conf.

When zeppelin.livy.restart_dead_session is turned on. dead livy session will be restarted automatically.
When it is turned off, proper message will be displayed in frontend, user can restart livy interpreter by himself after seeing this message.

And by default it is turned off, we encourage user to investigate why livy session is dead instead of restarting it for users.

[bikassaha]

zeppelin.livy.restart_dead_session - Is this an interpreter level setting? Will it start only that users livy session?

[zjffdu]

It would only restart that users livy session.