Log4J2 not working on Spring Boot on many levels - spring-boot

Question

I am trying to use log4j2 in a Spring Boot application, but it is going wrong on several levels.
This is a very simple Hello World application, just trying to get things working before I try it in production code. It is just a simple Initializr-generated Spring Boot application, with no added dependencies.
Problem #1 is that I am getting the following warnings, so I tried adding exclusions, but so far nothing is working
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/vgray/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/vgray/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.13.3/log4j-slf4j-impl-2.13.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
Here is the pom:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.4.2</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
<groupId>com.sample</groupId>
<artifactId>log4j2</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>log4j2</name>
<description>Demo project for Spring Boot</description>
<properties>
<java.version>11</java.version>
<log4j2.version>2.13.3</log4j2.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-log4j2</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
Problem #2 (I assume related) is that I have log4j2.xml in my src/main/resources dir, but it seems to be ignored.
Here is the log4j2.xml
<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn">
<Properties>
<Property name="basePath">E:\dev\log4j2\\logs</Property>
</Properties>
<Appenders>
<RollingFile name="fileLogger" fileName="${basePath}/app-info.log" filePattern="${basePath}/app-info-%d{yyyy-MM-dd}.log">
<PatternLayout>
<pattern>[%-5level] %d{MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n</pattern>
</PatternLayout>
<Policies>
<TimeBasedTriggeringPolicy interval="1" modulate="true" />
</Policies>
</RollingFile>
<Console name="console" target="SYSTEM_OUT">
<PatternLayout pattern="[%-5level] %d{MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n" />
</Console>
</Appenders>
<Loggers>
<Logger name="Log4j2Application" level="debug" additivity="true">
<appender-ref ref="fileLogger" level="debug" />
</Logger>
<Root level="debug" additivity="false">
<appender-ref ref="console" />
</Root>
</Loggers>
</Configuration>
I am assuming it is ignored, because the pattern is supposed to be MM-dd..., but the log messages are logging differently.
Here is my entire Spring Boot program:
package com.vgray.sample.log4j2;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
#SpringBootApplication
public class Log4j2Application {
private static final Logger logger = LogManager.getLogger("Log4j2Application");
public static void main(String[] args) {
logger.trace("A TRACE Message");
logger.debug("A DEBUG Message");
logger.info("An INFO Message");
logger.warn("A WARN Message");
logger.error("An ERROR Message");
logger.error("Error Message Logged !!!", new NullPointerException("NullError"));
SpringApplication.run(Log4j2Application.class, args);
}
}
Here is my entire log
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/C:/Users/vgray/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/C:/Users/vgray/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.13.3/log4j-slf4j-impl-2.13.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
21:20:18.355 [main] DEBUG Log4j2Application - A DEBUG Message
21:20:18.358 [main] INFO Log4j2Application - An INFO Message
21:20:18.358 [main] WARN Log4j2Application - A WARN Message
21:20:18.358 [main] ERROR Log4j2Application - An ERROR Message
21:20:18.361 [main] ERROR Log4j2Application - Error Message Logged !!!
java.lang.NullPointerException: NullError
at com.vgray.sample.log4j2.Log4j2Application.main(Log4j2Application.java:19)
21:20:18.531 [restartedMain] DEBUG Log4j2Application - A DEBUG Message
21:20:18.532 [restartedMain] INFO Log4j2Application - An INFO Message
21:20:18.532 [restartedMain] WARN Log4j2Application - A WARN Message
21:20:18.532 [restartedMain] ERROR Log4j2Application - An ERROR Message
21:20:18.532 [restartedMain] ERROR Log4j2Application - Error Message Logged !!!
java.lang.NullPointerException: NullError
at com.vgray.sample.log4j2.Log4j2Application.main(Log4j2Application.java:19)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.springframework.boot.devtools.restart.RestartLauncher.run(RestartLauncher.java:49)
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.4.2)
2021-02-28 21:20:19.087 INFO 69604 --- [ restartedMain] c.v.sample.log4j2.Log4j2Application : Starting Log4j2Application using Java 11.0.3 on DESKTOP-AM6DIPA with PID 69604 (E:\dev\log4j2\target\classes started by vgray in e:\dev\log4j2)
2021-02-28 21:20:19.089 INFO 69604 --- [ restartedMain] c.v.sample.log4j2.Log4j2Application : No active profile set, falling back to default profiles: default
2021-02-28 21:20:19.174 INFO 69604 --- [ restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : Devtools property defaults active! Set 'spring.devtools.add-properties' to 'false' to disable
2021-02-28 21:20:19.174 INFO 69604 --- [ restartedMain] .e.DevToolsPropertyDefaultsPostProcessor : For additional web related logging consider setting the 'logging.level.web' property to 'DEBUG'
2021-02-28 21:20:20.352 INFO 69604 --- [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2021-02-28 21:20:20.364 INFO 69604 --- [ restartedMain] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2021-02-28 21:20:20.364 INFO 69604 --- [ restartedMain] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.41]
2021-02-28 21:20:20.451 INFO 69604 --- [ restartedMain] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2021-02-28 21:20:20.451 INFO 69604 --- [ restartedMain] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 1275 ms
2021-02-28 21:20:20.657 INFO 69604 --- [ restartedMain] o.s.s.concurrent.ThreadPoolTaskExecutor : Initializing ExecutorService 'applicationTaskExecutor'
2021-02-28 21:20:20.829 INFO 69604 --- [ restartedMain] o.s.b.d.a.OptionalLiveReloadServer : LiveReload server is running on port 35729
2021-02-28 21:20:20.862 INFO 69604 --- [ restartedMain] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-02-28 21:20:20.876 INFO 69604 --- [ restartedMain] c.v.sample.log4j2.Log4j2Application : Started Log4j2Application in 2.33 seconds (JVM running for 3.718)

Answer 1

Sorry, cannot reproduce/works like a charm:
https://github.com/xerx593/soq66415875
Uses configuration from src/main/resources/log4j2.xml.
Prints DEBUG log messages to:
console as to
${working_dir}/app-info.log
(according to configuration) and exits.
Tiny(iest) changes to original Post:
removed (redundant) <log4j2.version/> from pom.xml (2.13.3 - same version as managed by spring-boot-starter:2.4.2)
relative addressing of the log file.
Output:
[DEBUG] 03-01 05:20:38.923 [main] Log4j2Application - A DEBUG Message
[INFO ] 03-01 05:20:38.938 [main] Log4j2Application - An INFO Message
[WARN ] 03-01 05:20:38.938 [main] Log4j2Application - A WARN Message
[ERROR] 03-01 05:20:38.938 [main] Log4j2Application - An ERROR Message
[ERROR] 03-01 05:20:38.938 [main] Log4j2Application - Error Message Logged !!!
java.lang.NullPointerException: NullError
at com.example.demo.Log4j2Application.main(Log4j2Application.java:18) [classes/:?]
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.4.2)
[INFO ] 03-01 05:20:39.839 [main] Log4j2Application - Starting Log4j2Application using Java 11.0.10 on rihanna with PID 9892 (D:\DEV\projects\soq66415875\target\classes started by xerx in D:\DEV\projects\soq66415875)
[DEBUG] 03-01 05:20:39.839 [main] Log4j2Application - Running with Spring Boot v2.4.2, Spring v5.3.3
[INFO ] 03-01 05:20:39.839 [main] Log4j2Application - No active profile set, falling back to default profiles: default
[DEBUG] 03-01 05:20:39.839 [main] SpringApplication - Loading source class com.example.demo.Log4j2Application
...
.... tons of debug messages, and finally:
...
org.springframework.boot.autoconfigure.info.ProjectInfoAutoConfiguration
[INFO ] 03-01 05:20:40.889 [main] Log4j2Application - Started Log4j2Application in 1.744 seconds (JVM running for 3.669)
[DEBUG] 03-01 05:20:40.904 [SpringContextShutdownHook] AnnotationConfigApplicationContext - Closing org.springframework.context.annotation.AnnotationConfigApplicationContext#54ec8cc9, started on Mon Mar 01 05:20:39 CET 2021
[DEBUG] 03-01 05:20:40.904 [SpringContextShutdownHook] AnnotationMBeanExporter - Unregistering JMX-exposed beans on shutdown
;) (or it is one/both of the tiny changes, or other "side effects")

Answer 2

I think both your problems arouse because you were not excluding the logging dependency from the spring-boot-starter-parent which you were including as the parent dependency. You need to exclude it from starter parent like:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<exclusions>
<exclusion>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-logging</artifactId>
</exclusion>
</exclusions>
</dependency>
Your pom.xml was excluding it from spring-boot-starter instead.