1. Add log4j2-appender module. 2. Implement KafkaAppender.

build.gradle

@@ -1914,6 +1914,28 @@ project(':log4j-appender') {
 
 }
 
+project(':log4j2-appender') {
+  archivesBaseName = "kafka-log4j2-appender"
+
+  dependencies {
+    compile project(':clients')
+    compile libs.log4j2Api
+    compile libs.log4j2Core
+    compile libs.slf4jlog4j2
+
+    testCompile project(':clients').sourceSets.test.output
+    testCompile libs.hamcrest
+    testCompile libs.junitJupiterApi
+    testCompile libs.junitVintageEngine
+    testCompile libs.log4j2CoreTest
+  }
+
+  javadoc {
+    enabled = false
+  }
+
+}
+
 project(':connect:api') {
   archivesBaseName = "connect-api"
 

checkstyle/import-control.xml

@@ -388,6 +388,13 @@
     <allow pkg="org.apache.kafka.test" />
   </subpackage>
 
+  <subpackage name="log4j2appender">
+    <allow pkg="org.apache.logging.log4j" />
+    <allow pkg="org.apache.kafka.clients" />
+    <allow pkg="org.apache.kafka.common" />
+    <allow pkg="org.apache.kafka.test" />
+  </subpackage>
+
   <subpackage name="test">
     <allow pkg="org.apache.kafka" />
     <allow pkg="org.bouncycastle" />

checkstyle/suppressions.xml

@@ -266,6 +266,12 @@
     <suppress checks="JavaNCSS"
               files="RequestResponseTest.java"/>
 
+    <!-- Log4J2-Appender -->
+    <suppress checks="CyclomaticComplexity"
+              files="KafkaAppender.java"/>
+    <suppress checks="NPathComplexity"
+              files="KafkaAppender.java"/>
+
     <!-- metadata -->
     <suppress checks="ClassDataAbstractionCoupling"
               files="(ReplicationControlManager|ReplicationControlManagerTest).java"/>

gradle/dependencies.gradle

@@ -76,6 +76,7 @@ versions += [
   jmh: "1.27",
   hamcrest: "2.2",
   log4j: "1.2.17",
+  log4j2: "2.13.3",
   scalaLogging: "3.9.2",
   jaxb: "2.3.0",
   jaxrs: "2.1.1",
@@ -176,6 +177,9 @@ libs += [
   kafkaStreams_26: "org.apache.kafka:kafka-streams:$versions.kafka_26",
   kafkaStreams_27: "org.apache.kafka:kafka-streams:$versions.kafka_27",
   log4j: "log4j:log4j:$versions.log4j",
+  log4j2Api: "org.apache.logging.log4j:log4j-api:$versions.log4j2",
+  log4j2Core: "org.apache.logging.log4j:log4j-core:$versions.log4j2",
+  log4j2CoreTest: "org.apache.logging.log4j:log4j-core:$versions.log4j2:tests",
   lz4: "org.lz4:lz4-java:$versions.lz4",
   metrics: "com.yammer.metrics:metrics-core:$versions.metrics",
   mockitoCore: "org.mockito:mockito-core:$versions.mockito",
@@ -194,6 +198,7 @@ libs += [
   scalatest: "org.scalatest:scalatest_$versions.baseScala:$versions.scalatest",
   slf4jApi: "org.slf4j:slf4j-api:$versions.slf4j",
   slf4jlog4j: "org.slf4j:slf4j-log4j12:$versions.slf4j",
+  slf4jlog4j2: "org.apache.logging.log4j:log4j-slf4j-impl:$versions.log4j2",
   snappy: "org.xerial.snappy:snappy-java:$versions.snappy",
   zookeeper: "org.apache.zookeeper:zookeeper:$versions.zookeeper",
   jfreechart: "jfreechart:jfreechart:$versions.jfreechart",