GraalVM native-image build failure using SLF4J and Log4j 2

Expected Behavior

The native-image command should build the image successfully.

Actual Behaviour

The native-image command fails trying to initialize org.apache.logging.slf4j.Log4jLogger at build time.

Is there a way to use log4j2 with native-image? I also tried using --initialize-at-build-time=org.apache.logging.slf4j.Log4jLogger but then another list of classes appears.

Output:

➜  micronaut-slf4j-log4j2 git:(master) native-image -jar build/libs/micronaut-slf4j-log4j2-0.1-all.jar --trace-class-initialization=org.apache.logging.slf4j.Log4jLogger
[micronaut-slf4j-log4j2-native-image:65072]    classlist:   2,661.67 ms,  1.19 GB
[micronaut-slf4j-log4j2-native-image:65072]        (cap):     411.13 ms,  1.19 GB
WARNING: Method com.sun.management.OperatingSystemMXBean.getCpuLoad() not found.
WARNING: Method com.sun.management.OperatingSystemMXBean.getCpuLoad() not found.
[micronaut-slf4j-log4j2-native-image:65072]        setup:   2,010.65 ms,  1.19 GB
WARNING: sun.reflect.Reflection.getCallerClass is not supported. This will impact performance.
[micronaut-slf4j-log4j2-native-image:65072]     analysis:   7,738.15 ms,  1.73 GB
Error: Classes that should be initialized at run time got initialized during image building:
 org.apache.logging.slf4j.Log4jLogger was unintentionally initialized at build time. io.micronaut.runtime.Micronaut caused initialization of this class with the following trace: 
	at org.apache.logging.slf4j.Log4jLogger.<clinit>(Log4jLogger.java:41)
	at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:39)
	at org.apache.logging.slf4j.Log4jLoggerFactory.newLogger(Log4jLoggerFactory.java:30)
	at org.apache.logging.log4j.spi.AbstractLoggerAdapter.getLogger(AbstractLoggerAdapter.java:53)
	at org.apache.logging.slf4j.Log4jLoggerFactory.getLogger(Log4jLoggerFactory.java:30)
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:358)
	at org.slf4j.LoggerFactory.getLogger(LoggerFactory.java:383)
	at io.micronaut.runtime.Micronaut.<clinit>(Micronaut.java:49)


Error: Use -H:+ReportExceptionStackTraces to print stacktrace of underlying exception
[micronaut-slf4j-log4j2-native-image:65072]      [total]:  12,597.98 ms,  1.73 GB
# Printing build artifacts to: /home/brunolellis/workspaces/micronaut-slf4j-log4j2/micronaut-slf4j-log4j2-native-image.build_artifacts.txt
Error: Image build request failed with exit status 1

Steps To Reproduce

1. sdk use java 21.2.0.r11-grl
2. ./gradlew clean build
3. native-image -jar build/libs/micronaut-slf4j-log4j2-0.1-all.jar

Environment Information

• Ubuntu 20.04: Linux brunolellis-T490 5.11.0-25-generic #27~20.04.1-Ubuntu SMP Tue Jul 13 17:41:23 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
• ghcr.io/graalvm/graalvm-ce:java11-21
• graalvm: 21.2.0.r11-grl

Example Application

https://github.com/brunolellis/micronaut-slf4j-log4j2

Version

2.5.12

[dstepanov]

Unfortunately, it’s log4j incompatibility with a native image, the issue should be reported to the log4j team. The workaround is to use log4j-over-slf4j. Nothing much we can do here.

[sschuberth]

The workaround is to use log4j-over-slf4j.

I guess alternatively to getting rid of the Log4j(2) implementation this way (in favor of whatever implementation you use with the SLF4J API, it’s logback in the above example), you could also stick with log4j-api (e.g. because you’re using it implicitly via log4j-api-kotlin) and take log4j-to-slf4j into use which “forwards” Log4j(2) API calls to the SLF4J API.