Chapter 20. The Build Environment

20.1. Configuring the build environment via

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, certain settings like JVM memory settings, Java home, daemon on/off can be more useful if they can be versioned with the project in your VCS so that the 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 file. The configuration is applied in following order (if an option is configured in multiple locations the last one wins):

  • from in project build dir.
  • from in gradle user home.
  • from system properties, e.g. when is set on the command line.

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


When set to true the Gradle daemon is used to run the build. For local developer builds this is our favorite property. The developer environment is optimized for speed and feedback so we nearly always run Gradle jobs with the daemon. We don't run CI builds with the daemon (i.e. a long running process) as the CI environment is optimized for consistency and reliability.

Specifies the Java home for the Gradle build process. The value can be set to either a jdk or jre location, however, depending on what your build does, jdk is safer. A reasonable default is used if the setting is unspecified.


Specifies the jvmargs used for the daemon process. The setting is particularly useful for tweaking memory settings. At the moment the default settings are pretty generous with regards to memory.


Enables new incubating mode that makes Gradle selective when configuring projects. Only relevant projects are configured which results in faster builds for large multi-projects. See Section, “Configuration on demand”.


When configured, Gradle will run in incubating parallel mode.


When configured, Gradle will use a maximum of the given number of workers. See --max-workers for details.

20.1.1. Forked Java processes

Many settings (like the Java version and maximum heap size) can only be specified when launching a new JVM for the build process. This means that Gradle must launch a separate JVM process to execute the build after parsing the various files. When running with the daemon, a JVM with the correct parameters is started once and reused for each daemon build execution. When Gradle is executed without the daemon, then a new JVM must be launched for every build execution, unless the JVM launched by the Gradle start script happens to have the same parameters.

This launching of an extra JVM on every build execution is quite expensive, which is why if you are setting either or org.gradle.jvmargs we highly recommend that you use the Gradle Daemon. See Chapter 18, The Gradle Daemon for more details.

20.2. Gradle properties and system properties

Gradle offers a variety of ways to add properties to your build. With 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 add properties to your project objects using properties files. You can place a file in the Gradle user home directory (defined by the “GRADLE_USER_HOME” environment variable, which if not set defaults to USER_HOME/.gradle) or in your project directory. For multi-project builds you can place files in any subproject directory. The properties set in a file can be accessed via the project object. The properties file in the user's home directory has precedence over property files in the project directories.

You can also 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. 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, typically for security reasons. In that situation, you can't use the -P option, and you can't 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. [8]

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.

You can also set system properties in the file. If a property name in such a file has the prefix “systemProp.”, like “systemProp.propName”, then the property and its value will be set as a system property, without the prefix. In a multi project build, “systemProp.” properties set in any project except the root will be ignored. That is, only the root project's file will be checked for properties that begin with the “systemProp.” prefix.

Example 20.1. Setting properties with a file



task printProps << {
    println commandLineProjectProp
    println gradlePropertiesProp
    println systemProjectProp
    println envProjectProp

Output of gradle -q -PcommandLineProjectProp=commandLineProjectPropValue -Dorg.gradle.project.systemProjectProp=systemPropertyValue printProps

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

20.2.1. Checking for project properties

You can access a project property in your build script simply by using its name as you would use a variable. If this property does not exist, an exception will be thrown and the build will fail. If your build script relies on optional properties the user might set, perhaps in a file, you need to check for existence before you access them. You can do this by using the method hasProperty('propertyName') which returns true or false.

20.3. Accessing the web via a proxy

Configuring an HTTP 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 proxy host would be done with System.setProperty('http.proxyHost', ''). Alternatively, the properties can be specified in a file, either in the build's root directory or in the Gradle home directory.

Example 20.2. Configuring an HTTP proxy

There are separate settings for HTTPS.

Example 20.3. Configuring an HTTPS proxy

We could not find a good overview for all possible proxy settings. One place to look are the constants in a file from the Ant project. Here's a link to the Subversion view. The other is a Networking Properties page from the JDK docs. If anyone knows of a better overview, please let us know via the mailing list.

20.3.1. NTLM Authentication

If your proxy requires NTLM authentication, you may need to provide the authentication domain as well as the username and password. There are 2 ways that you can provide the domain for authenticating to a NTLM proxy:

  • Set the http.proxyUser system property to a value like domain/username.
  • Provide the authentication domain via the http.auth.ntlm.domain system property.

[8] Jenkins, Teamcity, or Bamboo are some CI servers which offer this functionality.