Configuring lo4j2 logging with Tomcat embedded in a Spring Boot web app

Question

I have successfully configured my Spring Boot web app to use log4j2 with my configuration file below :

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN" monitorInterval="30">
<Properties>
    <Property name="LOG_PATTERN">
        %d{yyyy-MM-dd HH:mm:ss.SSS} %5p ${hostName} --- [%15.15t] %-40.40c{1.} : %m%n%ex
    </Property>
</Properties>
<Appenders>
    <Console name="ConsoleAppender" target="SYSTEM_OUT" follow="true">
        <PatternLayout pattern="${LOG_PATTERN}"/>
    </Console>
    <RollingFile name="FileAppender" fileName="${env:LEM_HOME}/Logs/LEM.log" 
                 filePattern="${env:LEM_HOME}/Logs/LEM-%d{yyyy-MM-dd}-%i.log">
        <PatternLayout>
            <Pattern>${LOG_PATTERN}</Pattern>
        </PatternLayout>
        <Policies>
            <SizeBasedTriggeringPolicy size="10MB" />
        </Policies>
        <DefaultRolloverStrategy max="10"/>
    </RollingFile>
</Appenders>
<Loggers>
    <Logger name="com.mdenis.labequipmentmanager" level="debug" additivity="false">
        <AppenderRef ref="ConsoleAppender" />
        <AppenderRef ref="FileAppender" />
    </Logger>
    <Logger name="org.apache.tomcat" level="debug" additivity="false">
        <AppenderRef ref="ConsoleAppender" />
        <AppenderRef ref="FileAppender" />
    </Logger>
    <Logger name="org.springframework" level="debug" additivity="false">
        <AppenderRef ref="ConsoleAppender" />
        <AppenderRef ref="FileAppender" />
    </Logger>
    <Logger name="org.hibernate" level="info" additivity="false">
        <AppenderRef ref="ConsoleAppender" />
        <AppenderRef ref="FileAppender" />
    </Logger>
    <Root level="error">
        <AppenderRef ref="ConsoleAppender"/>
    </Root>
</Loggers>
</Configuration>

I know it works because setting the log level for Spring to debug gives me about a million log entries when the app starts. Here is the POM.XML file for reference :

<?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 
http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>

<groupId>com.mdenis</groupId>
<artifactId>LEM2</artifactId>
<version>1.0-SNAPSHOT</version>

<name>Lab Equipment Manager</name>

<properties>
    <endorsed.dir>${project.build.directory}/endorsed</endorsed.dir>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>2.0.4.RELEASE</version>
</parent>

<dependencies>

    <!--JAVA-->
    <dependency>
        <groupId>javax.validation</groupId>
        <artifactId>validation-api</artifactId>
    </dependency>

    <!--TOMCAT-->
    <dependency>
        <groupId>org.apache.tomcat.embed</groupId>
        <artifactId>tomcat-embed-jasper</artifactId>
    </dependency>

    <!--SPRING-->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</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-jdbc</artifactId>
    </dependency>
    <!--<dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-security</artifactId>
    </dependency>-->
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-orm</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j2</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-devtools</artifactId>
        <optional>true</optional>
    </dependency>

    <!--MICROSOFT-->
    <dependency>
        <groupId>com.microsoft.sqlserver</groupId>
        <artifactId>mssql-jdbc</artifactId>
    </dependency>

    <!--HIBERNATE-->
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-validator</artifactId>
        <version>6.0.12.Final</version>
    </dependency>

    <!--LOMBOK-->
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
    </dependency>

    <!--JSTL-->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
    </dependency>

    <!--VMWARE-->
    <dependency>
        <groupId>com.vmware</groupId>
        <artifactId>vijava</artifactId>
        <version>5.1</version>
    </dependency>

    <!--LOG4J2-->
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-slf4j-impl</artifactId>
    </dependency>
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>slf4j-api</artifactId>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-api</artifactId>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-core</artifactId>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-1.2-api</artifactId>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-jcl</artifactId>
    </dependency>
    <dependency>
        <groupId>org.apache.logging.log4j</groupId>
        <artifactId>log4j-web</artifactId>
    </dependency>

</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
            <executions>
                <execution>
                    <goals>
                        <goal>repackage</goal>
                    </goals>
                </execution>
            </executions>
        </plugin>
    </plugins>
</build>

</project>

The only thing i'm unable to do is set Tomcat to debug level. With these settings I am able to set Hibernate to DEBUG mode also so i'm led to believe there is something specific with Tomcat.

Is there a way to control the Tomcat embedded logging level using log4j2 in the same way i'm doing with the other frameworks?

Thanks!

Answer 1

I searched a bit more and found how to do this. You need to add this to the java -jar command you run :

-Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager

For some reason, the logging level change cannot be done programmatically like I do with my own loggers so you have to put this in your log4j2.xml file :

    <Logger name="org.apache" level="debug" additivity="false">
        <AppenderRef ref="ConsoleAppenderWebClient" />
        <AppenderRef ref="FileAppenderWebClient" />
    </Logger>