ZEPPELIN-3527. replace log4j with reload4j

[Samrat002]

What is this PR for?

A few sentences describing the overall goals of the pull request's commits. First time? Check out the contributing guide - https://zeppelin.apache.org/contribution/contributions.html

What type of PR is it?

Improvement change from log4j to reload4j

Todos

• [ ] - Task

What is the Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-3527

[jongyoul]

Do you have any reason why you change to reload4j instead of log4j2?

[Reamer]

We should remove slf4j-log4j12 completely and replace it with the slf4j-api in the zeppelin code. Instead of log4j1 we should ship log4j2.

[Samrat002]

@jongyoul , greetings!!! Apologies for addressing bit late. I tried changing to log4j2 , and faced some of the issues which need many changes on entire logging As you must be aware that log4j2 has many srtructural and breaking changes from log4j1 , it is altering/touching some of the logging that is present / running . Even hadoop is moving towards reload4j and it sync with the log4j functionality Also i have tried in EMR clusters with zeppelin 0.10.1 version reload changes.

I am working more on it ! i will soon raise changes associted with log4j2.

[Samrat002]

@Reamer , greetings ! i am working on it to completely replace log4j with log4j2 and remove the usage of slf4j-log4j12 please allow me sometime to fix the error out and raise a pr for the same.

[Reamer]

@Reamer , greetings ! i am working on it to completely replace log4j with log4j2 and remove the usage of slf4j-log4j12 please allow me sometime to fix the error out and raise a pr for the same.

Please do not be afraid to remove the direct uses of Log4j1 in Zeppelin. I am aware that there will be function loss when working only with API of slf4j instead of directly with implementation log4j1.

Some code parts, which can be dropped. https://github.com/apache/zeppelin/blob/8995ff227a44760b7dbb005a85bee4ac7772e1f2/zeppelin-server/src/main/java/org/apache/zeppelin/rest/AdminRestApi.java#L56-L85 https://github.com/apache/zeppelin/blob/85ed8e2e51e1ea10df38d4710216343efe218d60/zeppelin-server/src/main/java/org/apache/zeppelin/service/AdminService.java#L32-L77 https://github.com/apache/zeppelin/blob/85ed8e2e51e1ea10df38d4710216343efe218d60/zeppelin-server/src/main/java/org/apache/zeppelin/rest/ZeppelinRestApi.java#L69-L89

[tangzhankun]

@Samrat002 thanks for the help. This is a critical fix. Any update on this? Seems the PR is outdated.

[Samrat002]

@tangzhankun I got occupied on my current company deliverables , wasnt able to make much of progress ! i am expecting to get quality time for this task from next week. If this is critical piece and need urgency , please feel free to pick or else i will be working on it from next week onwards

[tangzhankun]

@Samrat002 thanks a lot! I am not an expert as well. So please continue as your plan. Let me know if you have any blockers. I will try to help.

[tangzhankun]

@Samrat002 any updates on this?

[Geetha7891]

@Samrat002 Thanks a lot for your support. Let me try to work on this.