Build Environment

Gradle provides several options that make it easy to configure the Java process that will be used to execute your build. While it’s possible to configure these in your local environment via GRADLE_OPTS or JAVA_OPTS, it is useful to store certain settings like JVM memory configuration and Java home location in version control so that an entire team can work with a consistent environment.

Setting up a consistent environment for your build is as simple as placing these settings into a gradle.properties file. The configuration is applied in following order (if an option is configured in multiple locations the last one wins):

The following properties can be used to configure the Gradle build environment:

The following example demonstrates usage of various properties.

gradlePropertiesProp=gradlePropertiesValue
sysProp=shouldBeOverWrittenBySysProp
envProjectProp=shouldBeOverWrittenByEnvProp
systemProp.system=systemValue

task printProps {
    doLast {
        println commandLineProjectProp
        println gradlePropertiesProp
        println systemProjectProp
        println envProjectProp
        println System.properties['system']
    }
}

> gradle -q -PcommandLineProjectProp=commandLineProjectPropValue -Dorg.gradle.project.systemProjectProp=systemPropertyValue printProps
commandLineProjectPropValue
gradlePropertiesValue
systemPropertyValue
envPropertyValue
systemValue

Using the -D command-line option, you can pass a system property to the JVM which runs Gradle. The -D option of the gradle command has the same effect as the -D option of the java command.

You can also set system properties in gradle.properties files with the prefix systemProp.

systemProp.gradle.wrapperUser=myuser
systemProp.gradle.wrapperPassword=mypassword

The following system properties are available. Note that command-line options take precedence over system properties.

In a multi project build, “systemProp.” properties set in any project except the root will be ignored. That is, only the root project’s gradle.properties file will be checked for properties that begin with the “systemProp.” prefix.

The following environment variables are available for the gradle command. Note that command-line options and system properties take precedence over environment variables.

You can add properties directly to your Project object via the -P command line option.

Gradle can also set project properties when it sees specially-named system properties or environment variables. If the environment variable name looks like ORG_GRADLE_PROJECT_prop=somevalue, then Gradle will set a prop property on your project object, with the value of somevalue. Gradle also supports this for system properties, but with a different naming pattern, which looks like org.gradle.project.prop. Both of the following will set the foo property on your Project object to "bar".

org.gradle.project.foo=bar

ORG_GRADLE_PROJECT_foo=bar

This feature is very useful when you don’t have admin rights to a continuous integration server and you need to set property values that should not be easily visible. Since you cannot use the -P option in that scenario, nor change the system-level configuration files, the correct strategy is to change the configuration of your continuous integration build job, adding an environment variable setting that matches an expected pattern. This won’t be visible to normal users on the system.

You can access a project property in your build script simply by using its name as you would use a variable.

Gradle defaults to 1024 megabytes maximum heap per JVM process (-Xmx1024m), however, that may be too much or too little depending on the size of your project. There are many JVM options (this blog post on Java performance tuning and this reference may be helpful).

You can adjust JVM options for Gradle in the following ways:

The JAVA_OPTS environment variable is used for the Gradle client, but not forked JVMs.

JAVA_OPTS="-Xmx2g -XX:MaxPermSize=256m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8"

You need to use the org.gradle.jvmargs Gradle property to configure JVM settings for the Gradle Daemon.

org.gradle.jvmargs=-Xmx2g -XX:MaxPermSize=256m -XX:+HeapDumpOnOutOfMemoryError -Dfile.encoding=UTF-8

Certain tasks in Gradle also fork additional JVM processes, like the test task when using Test.setMaxParallelForks(int) for JUnit or TestNG tests. You must configure these through the tasks themselves.

apply plugin: "java"

tasks.withType(JavaCompile) {
    options.compilerArgs += ["-Xdoclint:none", "-Xlint:none", "-nowarn"]
}

See other examples in the Test API documentation and test execution in the Java plugin reference.

Build scans will tell you information about the JVM that executed the build when you use the --scan option.

It’s possible to change the behavior of a task based on project properties specified at invocation time.

Suppose you’d like to ensure release builds are only triggered by CI. A simple way to handle this is through an isCI project property.

task performRelease {
    doLast {
        if (project.hasProperty("isCI")) {
            println("Performing release actions")
        } else {
            throw new InvalidUserDataException("Cannot perform release outside of CI")
        }
    }
}

> gradle performRelease -PisCI=true --quiet
Performing release actions

Configuring an HTTP or HTTPS proxy (for downloading dependencies, for example) is done via standard JVM system properties. These properties can be set directly in the build script; for example, setting the HTTP proxy host would be done with System.setProperty('http.proxyHost', 'www.somehost.org'). Alternatively, the properties can be specified in gradle.properties.

systemProp.http.proxyHost=www.somehost.org
systemProp.http.proxyPort=8080
systemProp.http.proxyUser=userid
systemProp.http.proxyPassword=password
systemProp.http.nonProxyHosts=*.nonproxyrepos.com|localhost

There are separate settings for HTTPS.

systemProp.https.proxyHost=www.somehost.org
systemProp.https.proxyPort=8080
systemProp.https.proxyUser=userid
systemProp.https.proxyPassword=password
systemProp.https.nonProxyHosts=*.nonproxyrepos.com|localhost

You may need to set other properties to access other networks. Here are 2 references that may be helpful: