log4j2 not working in spring boot application

Question

I am trying to use log4j2 instead of logback in my spring application but it keep throwing error. The pom file looks like

<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.7.RELEASE</version>
    <relativePath /> 
</parent>

<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-web</artifactId>
    </dependency>

    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-log4j2</artifactId>
    </dependency>
</dependencies>

The log4j2 xml files looks like

<?xml version="1.0" encoding="UTF-8"?>
<Configuration monitorInterval="60">
    <Properties>
        <Property name="path">logs</Property>
    </Properties>
    <Appenders>
        <Console name="Console-Appender" target="SYSTEM_OUT">
            <PatternLayout>
                <pattern>
                    [%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n
                </pattern>>
            </PatternLayout>
        </Console>
        <File name="App-Appender" fileName="${path}/app_log.log" >
            <PatternLayout>
                <pattern>
                    [%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n
                </pattern>
            </PatternLayout>
        </File>
        <File name="SpringBoot-Appender" fileName="${path}/springboot_log.log" >
            <PatternLayout>
                <pattern>
                    [%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n
                </pattern>
            </PatternLayout>
        </File>
    </Appenders>
    <Loggers>
        <Logger name="master.dt" level="info" additivity="false">
            <AppenderRef ref="SpringBoot-Appender"/>
            <AppenderRef ref="Console-Appender"/>
        </Logger>
        <Logger name="master.dt" level="info" additivity="false">
            <AppenderRef ref="App-Appender"/>
            <AppenderRef ref="Console-Appender"/>
         </Logger>
        <Root>
            <AppenderRef ref="Console-Appender"/>
        </Root>
    </Loggers>
</Configuration>

however when i run the spring boot app it throws an error

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Users/asd.asd/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.6.2/log4j-slf4j-impl-2.6.2.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/Users/asd.asd/.m2/repository/ch/qos/logback/logback-classic/1.1.7/logback-classic-1.1.7.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 [org.apache.logging.slf4j.Log4jLoggerFactory]
[WARNING] 
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springframework.boot.maven.AbstractRunMojo$LaunchRunner.run(AbstractRunMojo.java:483)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.IllegalArgumentException: LoggerFactory is not a Logback LoggerContext but Logback is on the classpath. Either remove Logback or the competing implementation (class org.apache.logging.slf4j.Log4jLoggerFactory loaded from file:/Users/karan.shah/.m2/repository/org/apache/logging/log4j/log4j-slf4j-impl/2.6.2/log4j-slf4j-impl-2.6.2.jar). If you are using WebLogic you will need to add 'org.slf4j' to prefer-application-packages in WEB-INF/weblogic.xml Object of class [org.apache.logging.slf4j.Log4jLoggerFactory] must be an instance of class ch.qos.logback.classic.LoggerContext
    at org.springframework.util.Assert.isInstanceOf(Assert.java:346)
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.getLoggerContext(LogbackLoggingSystem.java:221)
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.getLogger(LogbackLoggingSystem.java:213)
    at org.springframework.boot.logging.logback.LogbackLoggingSystem.beforeInitialize(LogbackLoggingSystem.java:98)
    at org.springframework.boot.logging.LoggingApplicationListener.onApplicationStartedEvent(LoggingApplicationListener.java:222)

I followed multiple blog but none of them are working. What is the correct way to get log4j2 work?

Answer 1

Exclude the default spring boot starter logging dependency from spring boot starter web dependency also.

<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>

Answer 2

I faced this issue in Microservice based project which is based on many services. Because of lot of conflicts between log4j, slf4j , apache common logging etc. Hence log files is not creating even sufficient privileged are there. First run command to resolved the jar conflict from dependency tree.

**mvn dependency:tree**
Exclude those jars from spring-boot starter dependencies and other component dependencies.

Following Code is perfectly working for me after lot of struggle.

<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-log4j2</artifactId>
        </dependency>

****Log4j.xml files:****

        <?xml version="1.0" encoding="UTF-8"?>
        <Configuration>
            <Appenders>
                <Console name="Console" target="SYSTEM_OUT">
                    <PatternLayout
                        pattern="%style{%d{ISO8601}}{black} %highlight{%-5level }[%style{%t}{bright,blue}] %style{%C{1.}}{bright,yellow}: %msg%n%throwable" />
                </Console>

                <RollingFile name="RollingFile"
                    fileName="./logs/gateway-log4j2.log"
                    filePattern="./logs/$${date:yyyy-MM}/spring-boot-logger-log4j2-%d{-dd-MMMM-yyyy}-%i.log.gz">
                    <PatternLayout>
                        <pattern>%d %p %C{1.} [%t] %m%n</pattern>
                    </PatternLayout>
                    <Policies>
                        <!-- rollover on startup, daily and when the file reaches 
                            10 MegaBytes -->
                        <OnStartupTriggeringPolicy />
                        <SizeBasedTriggeringPolicy
                            size="10 MB" />
                        <TimeBasedTriggeringPolicy />
                    </Policies>
                </RollingFile>
            </Appenders>

            <Loggers>
                <!-- LOG everything at INFO level -->
                <Root level="info">
                    <AppenderRef ref="Console" />
                    <AppenderRef ref="RollingFile" />
                </Root>

                <!-- LOG "com.mytest.project*" at TRACE level -->
                <Logger name="com.mytest.project" level="trace"></Logger>
            </Loggers>

        </Configuration>

        Try it. It perfectly working for me.