See our web site for details on the project.

You need to have Java installed.

We build and test Apache Kafka with Java 8, 11, 17 and 20. We set the release parameter in javac and scalac to 8 to ensure the generated binaries are compatible with Java 8 or higher (independently of the Java version used for compilation). Java 8 support has been deprecated since Apache Kafka 3.0 and will be removed in Apache Kafka 4.0 (see KIP-750 for more details).

Scala 2.12 and 2.13 are supported and 2.13 is used by default. Scala 2.12 support has been deprecated since Apache Kafka 3.0 and will be removed in Apache Kafka 4.0 (see KIP-751 for more details). See below for how to use a specific Scala version or all of the supported Scala versions.

./gradlew jar

Follow instructions in https://kafka.apache.org/quickstart

./gradlew srcJar

./gradlew aggregatedJavadoc

./gradlew javadoc
./gradlew javadocJar # builds a javadoc jar for each module
./gradlew scaladoc
./gradlew scaladocJar # builds a scaladoc jar for each module
./gradlew docsJar # builds both (if applicable) javadoc and scaladoc jars for each module

./gradlew test # runs both unit and integration tests
./gradlew unitTest
./gradlew integrationTest

./gradlew test --rerun
./gradlew unitTest --rerun
./gradlew integrationTest --rerun

./gradlew clients:test --tests RequestResponseTest

I=0; while ./gradlew clients:test --tests RequestResponseTest --rerun --fail-fast; do (( I=$I+1 )); echo "Completed run: $I"; sleep 1; done

./gradlew core:test --tests kafka.api.ProducerFailureHandlingTest.testCannotSendToInternalTopic
./gradlew clients:test --tests org.apache.kafka.clients.MetadataTest.testTimeToNextUpdate

Change the log4j setting in either clients/src/test/resources/log4j.properties or core/src/test/resources/log4j.properties

./gradlew clients:test --tests RequestResponseTest

By default, each failed test is retried once up to a maximum of five retries per test run. Tests are retried at the end of the test task. Adjust these parameters in the following way:

./gradlew test -PmaxTestRetries=1 -PmaxTestRetryFailures=5

See Test Retry Gradle Plugin for more details.

Generate coverage reports for the whole project:

./gradlew reportCoverage -PenableTestCoverage=true -Dorg.gradle.parallel=false

Generate coverage for a single module, i.e.:

./gradlew clients:reportCoverage -PenableTestCoverage=true -Dorg.gradle.parallel=false

./gradlew clean releaseTarGz

The release file can be found inside ./core/build/distributions/.

Sometimes it is only necessary to rebuild the RPC auto-generated message data when switching between branches, as they could fail due to code changes. You can just run:

./gradlew processMessages processTestMessages

KAFKA_CLUSTER_ID="$(./bin/kafka-storage.sh random-uuid)"
./bin/kafka-storage.sh format -t $KAFKA_CLUSTER_ID -c config/kraft/server.properties
./bin/kafka-server-start.sh config/kraft/server.properties

./bin/zookeeper-server-start.sh config/zookeeper.properties
./bin/kafka-server-start.sh config/server.properties

./gradlew clean

Note that if building the jars with a version other than 2.13.x, you need to set the SCALA_VERSION variable or change it in bin/kafka-run-class.sh to run the quick start.

You can pass either the major version (eg 2.12) or the full version (eg 2.12.7):

./gradlew -PscalaVersion=2.12 jar
./gradlew -PscalaVersion=2.12 test
./gradlew -PscalaVersion=2.12 releaseTarGz

Invoke the gradlewAll script followed by the task(s):

./gradlewAll test
./gradlewAll jar
./gradlewAll releaseTarGz

This is for core, examples and clients

./gradlew core:jar
./gradlew core:test

Streams has multiple sub-projects, but you can run all the tests:

./gradlew :streams:testAll

./gradlew tasks

Note that this is not strictly necessary (IntelliJ IDEA has good built-in support for Gradle projects, for example).

./gradlew eclipse
./gradlew idea

The eclipse task has been configured to use ${project_dir}/build_eclipse as Eclipse's build directory. Eclipse's default build directory (${project_dir}/bin) clashes with Kafka's scripts directory and we don't use Gradle's build directory to avoid known issues with this configuration.

The recommended command is:

./gradlewAll publish

For backwards compatibility, the following also works:

./gradlewAll uploadArchives

Please note for this to work you should create/update ${GRADLE_USER_HOME}/gradle.properties (typically, ~/.gradle/gradle.properties) and assign the following variables