java.lang.ClassNotFoundException: net.logstash.logback.encoder.LogstashEncoder

Question

I am new to Scala and I am trying to generate logs in json format for an existing sbt project, but i am getting the error below -

java.lang.ClassNotFoundException: net.logstash.logback.encoder.LogstashEncoder

I have added these dependencies to the build.sbt

  "net.logstash.logback"  % "logstash-logback-encoder" % "4.11",
  "ch.qos.logback"        % "logback-core"             % "1.2.3",
  "ch.qos.logback"        % "logback-access"           % "1.2.3"

and my logback.xml looks like this -

<configuration>

    <appender name="FILE" class="ch.qos.logback.core.FileAppender">
        <file>app.log</file>
        <append>true</append>
        <!--<encoder>
            <pattern>%date{yyyy-MM-dd} %X{akkaTimestamp} %-5level[%thread] %logger{1} - %msg%n</pattern>
        </encoder>-->
        <encoder class="net.logstash.logback.encoder.LogstashEncoder"/>
    </appender>

    <root level="DEBUG">
        <appender-ref ref="FILE"/>
    </root>
</configuration>

Scala Version 2.12.3 SBT Version 1.0.3

Where I might be going wrong, any help will be appreciated .

Answer 1

I got same problem while building spring boot application.

I had defined encoder in logback-spring.xml

<encoder class="net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder">

The error message states that the required class cannot be found in the class path

java.lang.ClassNotFoundException: net.logstash.logback.encoder.LoggingEventCompositeJsonEncoder

In my case the problem was maven didn't fetch the dependencies which I modified in pom.xml for this encoder.

    <dependency> 
        <groupId>net.logstash.logback</groupId>
        <artifactId>logstash-logback-encoder</artifactId>
        <version>7.4</version>
    </dependency>

So, just make sure to perform mvn clean install and verify if the dependency can be seen in the external libraries