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Mirror of Apache Kafka
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hachikuji MINOR: Increase `awaitCommits` timeout in ExampleConnectIntegrationTe…
…st (#7061)

The transient failures are usually caused by a timeout in `awaitCommits`. This patch increases the timeout from 15s to 30s.

Reviewers: Konstantine Karantasis <>, Matthias J. Sax <>
Latest commit f65c71c Jul 16, 2019
Type Name Latest commit message Commit time
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bin KAFKA-8286; Generalized Leader Election Admin RPC (KIP-460) (#6686) May 29, 2019
checkstyle MINOR: Remove zkclient dependency (#7036) Jul 5, 2019
clients KAFKA-8662; Fix producer metadata error handling and consumer manual … Jul 16, 2019
config MINOR: Remove zkclient dependency (#7036) Jul 5, 2019
connect MINOR: Increase `awaitCommits` timeout in ExampleConnectIntegrationTe… Jul 16, 2019
core KAFKA-8662; Fix producer metadata error handling and consumer manual … Jul 16, 2019
docs Fixes #8198 KStreams testing docs use non-existent method pipe (#6678) Jul 12, 2019
examples KAFKA-7412: clarify the doc for producer callback (#5798) Nov 9, 2018
generator/src KAFKA-8644; The Kafka protocol generator should allow null defaults f… Jul 11, 2019
gradle KAFKA-8634: Update ZooKeeper to 3.5.5 (#6802) Jul 10, 2019
jmh-benchmarks KAFKA-8106: Skipping ByteBuffer allocation of key / value / headers i… Jun 21, 2019
log4j-appender/src MINOR: Remove deprecated assertThat usage from KafkaLog4jAppenderTest ( Feb 12, 2019
streams KAFKA-8450: Using KeyValueTimeStamp in MockProcessor (#6933) Jul 16, 2019
tests KAFKA-8634: Update ZooKeeper to 3.5.5 (#6802) Jul 10, 2019
tools/src MINOR: add useConfiguredPartitioner and skipFlush options for Produce… Jul 4, 2019
vagrant MINOR: Add compatibility tests for 2.3.0 (#6995) Jun 28, 2019
.gitignore KAFKA-7609; Add Protocol Generator for Kafka (#5893) Jan 12, 2019
.travis.yml MINOR: Add HttpMetricsReporter for system tests Nov 9, 2017 MINOR: Use https instead of http in links (#6477) Apr 22, 2019
HEADER trivial fix to add missing license header using .gradlew licenseForma… Feb 7, 2014
LICENSE KAFKA-4514; Add Codec for ZStandard Compression (#2267) Oct 10, 2018
NOTICE MINOR: Use https instead of http in links (#6477) Apr 22, 2019 MINOR: Exclude Committer Checklist section from commit message Nov 10, 2017 KAFKA-7197: Support Scala 2.13 (#5454) Jun 22, 2019 MINOR: Improve Trogdor external command worker docs (#6438) Jun 6, 2019
Vagrantfile MINOR: upgrade to jdk8 8u202 Jan 25, 2019
build.gradle KAFKA-8634: Update ZooKeeper to 3.5.5 (#6802) Jul 10, 2019
doap_Kafka.rdf MINOR: Use https instead of http in links (#6477) Apr 22, 2019 MINOR: Bump version to 2.4.0-SNAPSHOT (#6774) May 20, 2019 MINOR: Add verification step for Streams archetype to Jenkins build (#… Mar 21, 2019 MINOR: Bump version to 2.4.0-SNAPSHOT (#6774) May 20, 2019 HOTFIX: Change header back to http instead of https to path license h… Feb 28, 2019 MINOR: Use https instead of http in links (#6477) Apr 22, 2019
settings.gradle KAFKA-8155: Add 2.2.0 release to system tests (#6597) Jun 4, 2019
wrapper.gradle KAFKA-1490 remove gradlew initial setup output from source distributi… Sep 23, 2014

Apache Kafka

See our web site for details on the project.

You need to have Gradle and Java installed.

Kafka requires Gradle 5.0 or higher.

Java 8 should be used for building in order to support both Java 8 and Java 11 at runtime.

Scala 2.12 is used by default, see below for how to use a different Scala version or all of the supported Scala versions.

First bootstrap and download the wrapper

cd kafka_source_dir

Now everything else will work.

Build a jar and run it

./gradlew jar

Follow instructions in

Build source jar

./gradlew srcJar

Build aggregated javadoc

./gradlew aggregatedJavadoc

Build javadoc and scaladoc

./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

Run unit/integration tests

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

Force re-running tests without code change

./gradlew cleanTest test
./gradlew cleanTest unitTest
./gradlew cleanTest integrationTest

Running a particular unit/integration test

./gradlew clients:test --tests RequestResponseTest

Running a particular test method within a unit/integration test

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

Running a particular unit/integration test with log4j output

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

./gradlew clients:test --tests RequestResponseTest

Generating test coverage reports

Generate coverage reports for the whole project:

./gradlew reportCoverage

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

./gradlew clients:reportCoverage

Building a binary release gzipped tar ball

./gradlew clean releaseTarGz

The above command will fail if you haven't set up the signing key. To bypass signing the artifact, you can run:

./gradlew clean releaseTarGz -x signArchives

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

Cleaning the build

./gradlew clean

Running a task with one of the Scala versions available (2.11.x, 2.12.x or 2.13.x)

Note that if building the jars with a version other than 2.12.x, you need to set the SCALA_VERSION variable or change it in bin/ 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

Running a task with all the scala versions enabled by default

Append All to the task name:

./gradlew testAll
./gradlew jarAll
./gradlew releaseTarGzAll

Running a task for a specific project

This is for core, examples and clients

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

Listing all gradle tasks

./gradlew tasks

Building IDE project

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.

Publishing the jar for all version of Scala and for all projects to maven

./gradlew uploadArchivesAll

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


Publishing the streams quickstart archetype artifact to maven

For the Streams archetype project, one cannot use gradle to upload to maven; instead the mvn deploy command needs to be called at the quickstart folder:

cd streams/quickstart
mvn deploy

Please note for this to work you should create/update user maven settings (typically, ${USER_HOME}/.m2/settings.xml) to assign the following variables

<settings xmlns=""

Installing the jars to the local Maven repository

./gradlew installAll

Building the test jar

./gradlew testJar

Determining how transitive dependencies are added

./gradlew core:dependencies --configuration runtime

Determining if any dependencies could be updated

./gradlew dependencyUpdates

Running code quality checks

There are two code quality analysis tools that we regularly run, spotbugs and checkstyle.


Checkstyle enforces a consistent coding style in Kafka. You can run checkstyle using:

./gradlew checkstyleMain checkstyleTest

The checkstyle warnings will be found in reports/checkstyle/reports/main.html and reports/checkstyle/reports/test.html files in the subproject build directories. They are also are printed to the console. The build will fail if Checkstyle fails.


Spotbugs uses static analysis to look for bugs in the code. You can run spotbugs using:

./gradlew spotbugsMain spotbugsTest -x test

The spotbugs warnings will be found in reports/spotbugs/main.html and reports/spotbugs/test.html files in the subproject build directories. Use -PxmlSpotBugsReport=true to generate an XML report instead of an HTML one.

Common build options

The following options should be set with a -P switch, for example ./gradlew -PmaxParallelForks=1 test.

  • commitId: sets the build commit ID as .git/HEAD might not be correct if there are local commits added for build purposes.
  • mavenUrl: sets the URL of the maven deployment repository (file://path/to/repo can be used to point to a local repository).
  • maxParallelForks: limits the maximum number of processes for each task.
  • showStandardStreams: shows standard out and standard error of the test JVM(s) on the console.
  • skipSigning: skips signing of artifacts.
  • testLoggingEvents: unit test events to be logged, separated by comma. For example ./gradlew -PtestLoggingEvents=started,passed,skipped,failed test.
  • xmlSpotBugsReport: enable XML reports for spotBugs. This also disables HTML reports as only one can be enabled at a time.

Running system tests

See tests/

Running in Vagrant

See vagrant/


Apache Kafka is interested in building the community; we would welcome any thoughts or patches. You can reach us on the Apache mailing lists.

To contribute follow the instructions here:

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