LogbackAppenderApplicationListener breaks spring boot startup if logback is not on your classpath

[jkwatson-verta]

Describe the bug

If you use the instrumentation for spring-boot, but do not use spring-boot-starter-logging, but instead provide your own logging, that doesn't include logback, then this listener breaks spring-boot startup.

Steps to reproduce

Try to start up a spring-boot app that doesn't use logback. 💥

Expected behavior

Instrumentation should not break application startup.

Actual behavior

Spring boot will no longer start.

Javaagent or library instrumentation version

2.1.0-alpha

Environment

JDK: 21
OS: mac

Additional context

No response

[steverao]

I used 2.1.0 version to test and don't reproduce the phenomenon mentioned above. I follow the way to test that by excluding spring-boot-starter-logging and adding spring-boot-starter-log4j2. Can you use the version to verify whether there is the same problem you mentioned above?

[jeanbisutti]

Hi @steverao I think that it could have really a bug. Have you tried to display the dependency tree? Can you notice Logback dependencies on this tree?

[steverao]

Hi @steverao I think that it could have really a bug. Have you tried to display the dependency tree? Can you notice Logback dependencies on this tree?

I didn't see logback relevant dependency in the tree. Do you reproduce same problem?

[laurit]

I tried it out an to me it looks the same as #10612