log4j multiple SLF4J bindings integration issue

[shishir gowda]

Hi,

I am trying replace logback with log4j framework in my java playframework app (2.5.5), and have followed the guides but still see dependency issues wrt logback-classic.

I run it with: sbt -Dlog4j.configurationFile=normal/log4j2.xml

I get the following errors:

SLF4J: Class path contains multiple SLF4J bindings.

SLF4J: Found binding in [jar:file:/Users/shishir/repos/jio-money/jiomoney-wallet-backend/target/universal/stage/lib/ch.qos.logback.logback-classic-1.1.7.jar!/org/slf4j/impl/StaticLoggerBinder.class]

SLF4J: Found binding in [jar:file:/Users/shishir/repos/jio-money/jiomoney-wallet-backend/target/universal/stage/lib/org.apache.logging.log4j.log4j-slf4j-impl-2.4.1.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]

My build.sbt file updates are:

lazy val root = (project in file(".")).

  settings(commonSettings: _*).

  disablePlugins(PlayLogback)

libraryDependencies ++= Seq(...

    "org.apache.logging.log4j" % "log4j-slf4j-impl" % "2.4.1" exclude("ch.qos.logback", "logback-classic"),

    "org.apache.logging.log4j" % "log4j-api" % "2.4.1"  exclude("ch.qos.logback", "logback-core"),

    "org.apache.logging.log4j" % "log4j-core" % "2.4.1"

)

My log4j2.xml is:

<?xml version="1.0" encoding="UTF-8"?>

<Configuration status="WARN">

    <Appenders>

        <Console name="console" target="SYSTEM_OUT">

            <PatternLayout pattern="[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n"/>

        </Console>

        <File name="file" target="/tmp/app.log">

            <PatternLayout pattern="[%-5level] %d{yyyy-MM-dd HH:mm:ss.SSS} [%t] %c{1} - %msg%n"/>

        </File>

    </Appenders>

    <Loggers>

        <Root level="info" additivity="true">

            <AppenderRef ref="console"/ level="DEBUG">

            <AppenderRef ref="file"/ level="TRACE">

        </Root>

    </Loggers>

</Configuration> 

Please let me know if I am doing anything wrong, or missing anything.

[Marcos Pereira]

Hey, 

Maybe logback is being pulled transitively by another dependency. You can use sbt-dependency-graph to check that.

Best.

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Marcos Pereira

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[Will Sargent]

You've got two different SLF4J implementations in your classpath somehow.  Something else in your classpath is pulling in a logging engine.

There's a blog post and an example that should help so you can verify you've got the basic project down.

http://www.codepreference.com/2016/06/using-log4j2-for-play-application.html