logback configuration defined via JAVA_TOOL_OPTIONS is ignored

[vekonypeter]

Expected Behavior

When the path to the logback.xml file is defined in the JAVA_TOOL_OPTIONS environment variable (like e.g.: JAVA_TOOL_OPTIONS=-Dlogback.configurationFile=/path/to/logback-external.xml) this configuration should be used

Actual Behaviour

The external logback XML file is used as expected until the end of the bean registration phase. From that point, the framework switches back to the default logback.xml file placed under the resources folder.

This behaviour was introduced in PR #8238, it's caused by this method: https://github.com/micronaut-projects/micronaut-core/blob/3.8.x/management/src/main/java/io/micronaut/management/endpoint/loggers/impl/LogbackLoggingSystem.java#L135-L149

Steps To Reproduce

1. define e.g. logback-external.xml file either in the resources folder or anywhere else. Make sure that it logs somehow differently than the default logback.xml.
2. run the application with JAVA_TOOL_OPTIONS=-Dlogback.configurationFile=/path/to/logback-external.xml environment variable
3. configuration defined in logback-external.xml is ignored once the application started up

Environment Information

• Micronaut version: 3.8.0 - everything works fine below that
• Operating system: MacOS
• JVM: Temurin-17.0.5+8

Example Application

No response

Version

3.8.0

[driverpt]

Try to set -Dlogger.config=/path/to/logback-external.xml.

[adamkobor]

@driverpt Unfortunately this doesn't work if the config file is not on your classpath (e.g. attached through a volume in the container)

[ckosmowski]

This is also a real issue for us because we use this feature to inject logback configuration in a kubernetes environment and with an update to 3.8.x the services won't start up anymore complaining about logback.xml is mssing.

[albrechtflo-hg]

I checked out the LogbackUtils code which loads the config into Logback, and I really cannot understand why this is limited to the Classpath. The resource is mapped to a URL anyway in that class, so why not use just a little cleverer approach to look up the resource?
@driverpt @graemerocher This should really be looked into, as it really is a huge regression when upgrading Micronaut.