Changing subsystem on Logging page changes all subsystems

[bernd]

Problem description

Changing any Subsystem on the Logging page (except "Subsystem: Graylog") changes the level for all subsystems.

Steps to reproduce the problem

1. Go to System/Logging
2. Select "debug" for "Subsystem: Indexer"
3. Log level for "Sockets", "Indexer" and "Authentication" changes to "debug"
4. Check API request "/system/loggers/subsystems", same issue (so it's not a UI problem)

Analysis

It looks like the LoggersResource#setLoggerLevel() method changes the root logger instead of the requested class because there is no explicit config for that. The graylog subsystem does not change because our default log4j2.xml has an explicit configuration for that.

I guess this is a behaviour change in log4j2.

Environment

• Graylog Version: 2.0.0-alpha.5
• Elasticsearch Version: 2.2.0
• MongoDB Version: 2.4.14
• Operating System: Ubuntu 14.04