[FLINK-15672] Switch to Log4j 2 by default

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.11.0
• Component/s: Build System
• Labels: pull-request-available usability

Release Note

Flink now uses Log4j2 by default.

Users who wish to revert back to Log4j1 can find instructions to do so in the logging documentation.

• Assignee: Chesnay Schepler
• Reporter: Stephan Ewen
• Created: 19/Jan/20 23:08
• Updated: 10/Dec/21 11:47
• Resolved: 21/Feb/20 13:50

Description

Log4j 1.x is outdated and has multiple problems:

• No dynamic adjustments of Log Level
• Problems with newer Java Versions
• Not actively developed any more

Switching to Log4J 2 by default would solve this.

Issue Links

• causes: FLINK-16237 Several places missing Log4j2 configuration property
• causes: FLINK-16287 ES6 sql jar relocates log4j2
• contains: FLINK-5339 Ensure Flink works with Log4j version 2
• is related to: FLINK-25258 Update log4j2 version to 2.15.0-rc2
• is related to: FLINK-16243 Update quickstart documentation to Log4j2
• is related to: FLINK-5339 Ensure Flink works with Log4j version 2
• is related to: FLINK-16232 Remove redundant log4j2 exclusions from hive connector
• is related to: FLINK-16253 Switch to Log4j 2 by default for flink-kubernetes submodule
• links to: GitHub Pull Request #11073