Apache Kafka
=================
See our [web site](http://kafka.apache.org) for details on the project.

You need to have [Gradle](http://www.gradle.org/installation) and [Java](http://www.oracle.com/technetwork/java/javase/downloads/index.html) installed.

Kafka requires Gradle 2.0 or higher.

Java 7 should be used for building in order to support both Java 7 and Java 8 at runtime.

### First bootstrap and download the wrapper ###
    cd kafka_source_dir
    gradle

Now everything else will work.

### Building a jar and running it ###
    ./gradlew jar

Follow instructions in http://kafka.apache.org/documentation.html#quickstart

### Building source jar ###
    ./gradlew srcJar

### Building aggregated javadoc ###
    ./gradlew aggregatedJavadoc

### Building 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

### Running unit tests ###
    ./gradlew test

### Forcing re-running unit tests w/o code change ###
    ./gradlew cleanTest test

### Running a particular unit test ###
    ./gradlew -Dtest.single=RequestResponseSerializationTest core:test

### Running a particular test method within a unit test ###
    ./gradlew core:test --tests kafka.api.ProducerFailureHandlingTest.testCannotSendToInternalTopic
    ./gradlew clients:test --tests org.apache.kafka.clients.MetadataTest.testMetadataUpdateWaitTime

### Running a particular unit test with log4j output ###
Change the log4j setting in either `clients/src/test/resources/log4j.properties` or `core/src/test/resources/log4j.properties`

    ./gradlew -i -Dtest.single=RequestResponseSerializationTest core:test

### 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
    ./gradlew releaseTarGz

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

    ./gradlew releaseTarGz -x signArchives

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

### Cleaning the build ###
    ./gradlew clean

### Running a task on a particular version of Scala (either 2.10.6 or 2.11.8) ###
*Note that if building the jars with a version other than 2.10.6, 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 2.11) or the full version (eg 2.11.8):

    ./gradlew -PscalaVersion=2.11 jar
    ./gradlew -PscalaVersion=2.11 test
    ./gradlew -PscalaVersion=2.11 releaseTarGz

### 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.

### Building the jar for all scala versions and for all projects ###
    ./gradlew jarAll

### Running unit tests for all scala versions and for all projects ###
    ./gradlew testAll

### Building a binary release gzipped tar ball for all scala versions ###
    ./gradlew releaseTarGzAll

### 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}/gradle.properties` (typically, `~/.gradle/gradle.properties`) and assign the following variables

    mavenUrl=
    mavenUsername=
    mavenPassword=
    signing.keyId=
    signing.password=
    signing.secretKeyRingFile=

### 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, findbugs and checkstyle.

#### 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.

#### Findbugs
Findbugs uses static analysis to look for bugs in the code.
You can run findbugs using:

    ./gradlew findbugsMain findbugsTest -x test

The findbugs warnings will be found in `reports/findbugs/main.html` and `reports/findbugs/test.html` files in the subproject build
directories. Currently, findbugs warnings do not cause the build to fail.

### Common build options ###

The following options should be set with a `-D` switch, for example `./gradlew -Dorg.gradle.project.maxParallelForks=1 test`.

* `org.gradle.project.mavenUrl`: sets the URL of the maven deployment repository (`file://path/to/repo` can be used to point to a local repository).
* `org.gradle.project.maxParallelForks`: limits the maximum number of processes for each task.
* `org.gradle.project.showStandardStreams`: shows standard out and standard error of the test JVM(s) on the console.
* `org.gradle.project.skipSigning`: skips signing of artifacts.
* `org.gradle.project.testLoggingEvents`: unit test events to be logged, separated by comma. For example `./gradlew -Dorg.gradle.project.testLoggingEvents=started,passed,skipped,failed test`

### Running in Vagrant ###

See [vagrant/README.md](vagrant/README.md).

### Contribution ###

Apache Kafka is interested in building the community; we would welcome any thoughts or [patches](https://issues.apache.org/jira/browse/KAFKA). You can reach us [on the Apache mailing lists](http://kafka.apache.org/contact.html).

To contribute follow the instructions here:
 * http://kafka.apache.org/contributing.html