SpringBoot Log4j2 classpath resource not found when using Spring Boot and GraalVM

Description

When using Spring Boot, Log4j 2.24.0, and GraalVM, the application cannot start because it can't find classpath resource log4j2.xml.

Error message: java.io.FileNotFoundException: class path resource [org/springframework/boot/logging/log4j2/log4j2.xml] cannot be resolved to URL because it does not exist

Configuration

Spring Boot version: 3.3.3

Operating system: MacOS/GraalVM

JDK: GraalVM 22

Logs

Logging system failed to initialize using configuration from 'null'
java.io.FileNotFoundException: class path resource [org/springframework/boot/logging/log4j2/log4j2.xml] cannot be resolved to URL because it does not exist
        at org.springframework.core.io.ClassPathResource.getURL(ClassPathResource.java:230)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.getConfigurationSource(Log4J2LoggingSystem.java:289)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.load(Log4J2LoggingSystem.java:281)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:266)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.load(Log4J2LoggingSystem.java:244)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadDefaults(Log4J2LoggingSystem.java:230)
        at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:84)
        at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:61)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.initialize(Log4J2LoggingSystem.java:223)
        at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:332)
        at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:298)
        at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)
        at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:185)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:178)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:156)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:138)
        at org.springframework.boot.context.event.EventPublishingRunListener.multicastInitialEvent(EventPublishingRunListener.java:136)
        at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:81)
        at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:64)
        at java.base@22.0.2/java.lang.Iterable.forEach(Iterable.java:75)
        at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:118)
        at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:112)
        at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:63)
        at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:370)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:330)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1363)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1352)
        at com.example.log4j2test.Log4j2TestApplication.main(Log4j2TestApplication.java:10)
        at java.base@22.0.2/java.lang.invoke.LambdaForm$DMH/sa346b79c.invokeStaticInit(LambdaForm$DMH)
Application run failed
java.lang.IllegalStateException: java.lang.IllegalStateException: Could not initialize Log4J2 logging from classpath:org/springframework/boot/logging/log4j2/log4j2.xml
        at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:347)
        at org.springframework.boot.context.logging.LoggingApplicationListener.initialize(LoggingApplicationListener.java:298)
        at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEnvironmentPreparedEvent(LoggingApplicationListener.java:246)
        at org.springframework.boot.context.logging.LoggingApplicationListener.onApplicationEvent(LoggingApplicationListener.java:223)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.doInvokeListener(SimpleApplicationEventMulticaster.java:185)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:178)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:156)
        at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:138)
        at org.springframework.boot.context.event.EventPublishingRunListener.multicastInitialEvent(EventPublishingRunListener.java:136)
        at org.springframework.boot.context.event.EventPublishingRunListener.environmentPrepared(EventPublishingRunListener.java:81)
        at org.springframework.boot.SpringApplicationRunListeners.lambda$environmentPrepared$2(SpringApplicationRunListeners.java:64)
        at java.base@22.0.2/java.lang.Iterable.forEach(Iterable.java:75)
        at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:118)
        at org.springframework.boot.SpringApplicationRunListeners.doWithListeners(SpringApplicationRunListeners.java:112)
        at org.springframework.boot.SpringApplicationRunListeners.environmentPrepared(SpringApplicationRunListeners.java:63)
        at org.springframework.boot.SpringApplication.prepareEnvironment(SpringApplication.java:370)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:330)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1363)
        at org.springframework.boot.SpringApplication.run(SpringApplication.java:1352)
        at com.example.log4j2test.Log4j2TestApplication.main(Log4j2TestApplication.java:10)
        at java.base@22.0.2/java.lang.invoke.LambdaForm$DMH/sa346b79c.invokeStaticInit(LambdaForm$DMH)
Caused by: java.lang.IllegalStateException: Could not initialize Log4J2 logging from classpath:org/springframework/boot/logging/log4j2/log4j2.xml
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:275)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.load(Log4J2LoggingSystem.java:244)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadDefaults(Log4J2LoggingSystem.java:230)
        at org.springframework.boot.logging.AbstractLoggingSystem.initializeWithConventions(AbstractLoggingSystem.java:84)
        at org.springframework.boot.logging.AbstractLoggingSystem.initialize(AbstractLoggingSystem.java:61)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.initialize(Log4J2LoggingSystem.java:223)
        at org.springframework.boot.context.logging.LoggingApplicationListener.initializeSystem(LoggingApplicationListener.java:332)
        ... 20 more
Caused by: java.io.FileNotFoundException: class path resource [org/springframework/boot/logging/log4j2/log4j2.xml] cannot be resolved to URL because it does not exist
        at org.springframework.core.io.ClassPathResource.getURL(ClassPathResource.java:230)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.getConfigurationSource(Log4J2LoggingSystem.java:289)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.load(Log4J2LoggingSystem.java:281)
        at org.springframework.boot.logging.log4j2.Log4J2LoggingSystem.loadConfiguration(Log4J2LoggingSystem.java:266)
        ... 26 more

Reproduction

Here's a repo I created with a minimal example of the bug. Follow the steps in the README to reproduce the bug.

https://github.com/brendenehlers/log4j-graalvm-error

Issue with Log4j2 team: https://github.com/apache/logging-log4j2/issues/2945

Comment From: philwebb

Log4j2 isn't supported in a native image. It requires extensive changes to Log4j2 for it to work. Please see LOG4J2-2649 for further details.

Comment From: ppkarwasz

Hi @philwebb,

Log4j2 isn't supported in a native image. It requires extensive changes to Log4j2 for it to work.

With the release of version 2.25.0, log4j-core and its extensions now include an embedded reflect-config.json file. These changes likely address the extensive modifications you mentioned. Would you consider reopening this issue to discuss further?

Since org/springframework/boot/logging/log4j2/log4j2.xml, org/springframework/boot/logging/log4j2/log4j2-file.xml, and log4j2.springboot are specific to Spring Boot, they should be handled through a RuntimeHintsRegistrar, similar to how LogbackRuntimeHints manages Logback configuration.