SslConfig is null when trying to capture logs using Syslog with TLS #4026
Description
Description
Essentially, I am trying to test the sending of log messages using Syslog over TLS protocol. My tests work completely fine with TCP but break for a number of reasons (since we've upgraded from JDK17 -> 21). The trust store is being set programmatically along with the 'SSL' protocol. However, I encounter issues whereby you get NPE's for it being unable to initialise the SSL Configuration required.
With an SSL block it 'seems' to work, but that hasn't been required before and as per the log4j docs should still not be required as long as the system variables for the trustStore etc are being set before any appenders are created. Would greatly appreciate any assistance on this 🙇 .
Configuration
Version: 2.25.3
Operating system: Windows 11
JDK: JDK21
Logs
2026-01-20T12:20:03.986235Z pool-2-thread-1 @coroutine#3 ERROR Could not create plugin of type class org.apache.logging.log4j.core.appender.SyslogAppender for element Syslog: java.lang.NullPointerException: Cannot invoke "org.apache.logging.log4j.core.net.ssl.SslConfiguration.getKeyStoreConfig()" because "sslConfig" is null
java.lang.NullPointerException: Cannot invoke "org.apache.logging.log4j.core.net.ssl.SslConfiguration.getKeyStoreConfig()" because "sslConfig" is null
at org.apache.logging.log4j.core.net.SslSocketManager.createSslConfigurationId(SslSocketManager.java:252)
at org.apache.logging.log4j.core.net.SslSocketManager.getSocketManager(SslSocketManager.java:227)
at org.apache.logging.log4j.core.appender.SocketAppender.createSocketManager(SocketAppender.java:579)
at org.apache.logging.log4j.core.appender.SyslogAppender$Builder.build(SyslogAppender.java:151)
at org.apache.logging.log4j.core.appender.SyslogAppender$Builder.build(SyslogAppender.java:49)
at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:124)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:1206)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1125)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1117)
at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:715)
at org.apache.logging.log4j.core.config.AbstractConfiguration.initialize(AbstractConfiguration.java:271)
at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:324)
at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:697)
at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:786)
at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:808)
at org.apache.logging.log4j.core.config.Configurator.reconfigure(Configurator.java:281)
at io.kotest.core.spec.ListenersKt$functionOverrideCallbacks$1.beforeEach(listeners.kt:41)
at io.kotest.engine.test.TestExtensions.beforeTestBeforeAnyBeforeContainer-gIAlu-s(TestExtensions.kt:80)
at io.kotest.engine.test.interceptors.LifecycleInterceptor.intercept(LifecycleInterceptor.kt:47)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invokeSuspend(TestCaseExtensionInterceptor.kt:24)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invoke(TestCaseExtensionInterceptor.kt)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invoke(TestCaseExtensionInterceptor.kt)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1$1.invokeSuspend(TestExtensions.kt:143)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1$1.invoke(TestExtensions.kt)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1$1.invoke(TestExtensions.kt)
at io.micronaut.test.extensions.kotest5.MicronautKotest5Extension.intercept(MicronautKotest5Extension.kt:42)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1.invokeSuspend(TestExtensions.kt:140)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1.invoke(TestExtensions.kt)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1.invoke(TestExtensions.kt)
at io.kotest.engine.test.TestExtensions.intercept(TestExtensions.kt:148)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor.intercept(TestCaseExtensionInterceptor.kt:24)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor$intercept$runTest$1$4$1.invokeSuspend(BeforeSpecListenerInterceptor.kt:50)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor$intercept$runTest$1$4$1.invoke(BeforeSpecListenerInterceptor.kt)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor$intercept$runTest$1$4$1.invoke(BeforeSpecListenerInterceptor.kt)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor.intercept(BeforeSpecListenerInterceptor.kt:60)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.TestEnabledCheckInterceptor.intercept(TestEnabledCheckInterceptor.kt:31)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invokeSuspend(CoroutineErrorCollectorInterceptor.kt:34)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invoke(CoroutineErrorCollectorInterceptor.kt)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invoke(CoroutineErrorCollectorInterceptor.kt)
at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndspatched(Undispatched.kt:66)
at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:43)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.withContext(Builders.common.kt:165)
at kotlinx.coroutines.BuildersKt.withContext(Unknown Source)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor.intercept(CoroutineErrorCollectorInterceptor.kt:33)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invokeSuspend(coroutineDispatcherFactoryInterceptor.kt:57)
at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invoke(coroutineDispatcherFactoryInterceptor.kt)
at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invoke(coroutineDispatcherFactoryInterceptor.kt)
at io.kotest.engine.concurrency.FixedThreadCoroutineDispatcherFactory$withDispatcher$4.invokeSuspend(FixedThreadCoroutineDispatcherFactory.kt:59)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:34)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
2026-01-20T12:20:03.995535800Z pool-2-thread-1 @coroutine#3 ERROR Unable to invoke factory method in class org.apache.logging.log4j.core.appender.SyslogAppender for element Syslog: java.lang.IllegalStateException: No factory method found for class org.apache.logging.log4j.core.appender.SyslogAppender
java.lang.IllegalStateException: No factory method found for class org.apache.logging.log4j.core.appender.SyslogAppender
at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.findFactoryMethod(PluginBuilder.java:268)
at org.apache.logging.log4j.core.config.plugins.util.PluginBuilder.build(PluginBuilder.java:140)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createPluginObject(AbstractConfiguration.java:1206)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1125)
at org.apache.logging.log4j.core.config.AbstractConfiguration.createConfiguration(AbstractConfiguration.java:1117)
at org.apache.logging.log4j.core.config.AbstractConfiguration.doConfigure(AbstractConfiguration.java:715)
at org.apache.logging.log4j.core.config.AbstractConfiguration.initialize(AbstractConfiguration.java:271)
at org.apache.logging.log4j.core.config.AbstractConfiguration.start(AbstractConfiguration.java:324)
at org.apache.logging.log4j.core.LoggerContext.setConfiguration(LoggerContext.java:697)
at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:786)
at org.apache.logging.log4j.core.LoggerContext.reconfigure(LoggerContext.java:808)
at org.apache.logging.log4j.core.config.Configurator.reconfigure(Configurator.java:281)
at io.kotest.core.spec.ListenersKt$functionOverrideCallbacks$1.beforeEach(listeners.kt:41)
at io.kotest.engine.test.TestExtensions.beforeTestBeforeAnyBeforeContainer-gIAlu-s(TestExtensions.kt:80)
at io.kotest.engine.test.interceptors.LifecycleInterceptor.intercept(LifecycleInterceptor.kt:47)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invokeSuspend(TestCaseExtensionInterceptor.kt:24)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invoke(TestCaseExtensionInterceptor.kt)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor$intercept$2.invoke(TestCaseExtensionInterceptor.kt)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1$1.invokeSuspend(TestExtensions.kt:143)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1$1.invoke(TestExtensions.kt)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1$1.invoke(TestExtensions.kt)
at io.micronaut.test.extensions.kotest5.MicronautKotest5Extension.intercept(MicronautKotest5Extension.kt:42)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1.invokeSuspend(TestExtensions.kt:140)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1.invoke(TestExtensions.kt)
at io.kotest.engine.test.TestExtensions$intercept$execute$1$1.invoke(TestExtensions.kt)
at io.kotest.engine.test.TestExtensions.intercept(TestExtensions.kt:148)
at io.kotest.engine.test.interceptors.TestCaseExtensionInterceptor.intercept(TestCaseExtensionInterceptor.kt:24)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor$intercept$runTest$1$4$1.invokeSuspend(BeforeSpecListenerInterceptor.kt:50)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor$intercept$runTest$1$4$1.invoke(BeforeSpecListenerInterceptor.kt)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor$intercept$runTest$1$4$1.invoke(BeforeSpecListenerInterceptor.kt)
at io.kotest.engine.test.interceptors.BeforeSpecListenerInterceptor.intercept(BeforeSpecListenerInterceptor.kt:60)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.TestEnabledCheckInterceptor.intercept(TestEnabledCheckInterceptor.kt:31)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invokeSuspend(CoroutineErrorCollectorInterceptor.kt:34)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invoke(CoroutineErrorCollectorInterceptor.kt)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor$intercept$3.invoke(CoroutineErrorCollectorInterceptor.kt)
at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndspatched(Undispatched.kt:66)
at kotlinx.coroutines.intrinsics.UndispatchedKt.startUndispatchedOrReturn(Undispatched.kt:43)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.withContext(Builders.common.kt:165)
at kotlinx.coroutines.BuildersKt.withContext(Unknown Source)
at io.kotest.engine.test.interceptors.CoroutineErrorCollectorInterceptor.intercept(CoroutineErrorCollectorInterceptor.kt:33)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invokeSuspend(TestCaseExecutor.kt:100)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.TestCaseExecutor$execute$3$1.invoke(TestCaseExecutor.kt)
at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invokeSuspend(coroutineDispatcherFactoryInterceptor.kt:57)
at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invoke(coroutineDispatcherFactoryInterceptor.kt)
at io.kotest.engine.test.interceptors.CoroutineDispatcherFactoryInterceptor$intercept$4.invoke(coroutineDispatcherFactoryInterceptor.kt)
at io.kotest.engine.concurrency.FixedThreadCoroutineDispatcherFactory$withDispatcher$4.invokeSuspend(FixedThreadCoroutineDispatcherFactory.kt:59)
at kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith(ContinuationImpl.kt:34)
at kotlinx.coroutines.DispatchedTask.run(DispatchedTask.kt:100)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at java.base/java.lang.Thread.run(Unknown Source)
2026-01-20T12:20:04.004096Z pool-2-thread-1 @coroutine#3 ERROR Null object returned for Syslog in Appenders.
2026-01-20T12:20:04.020423300Z pool-2-thread-1 @coroutine#3 ERROR Unable to locate appender "LogToSyslog" for logger config "root"
Reproduction
I've converted my kotlin code into a basic JUnit test that aims to send a log message via TLS through Syslog. Apologies for not providing a comprehensive test in this case but the kotlin file should have enough to be able to run. You might just need to setup a basic GenericContainer companion class that uses the image 'balabit/syslog-ng:4.4.0'.