# Configuring the Build Environment

version 8.9

Configuring the build environment is a powerful way to customize the build process. There are many mechanisms available. By leveraging these mechanisms, you can make your Gradle builds more flexible and adaptable to different environments and requirements.

## Available mechanisms

Gradle provides multiple mechanisms for configuring the behavior of Gradle itself and specific projects:

Mechanism | Information | Example
--- | --- | ---
Command line interface | Flags that configure build behavior and Gradle features | `--rerun`
Project properties | Properties specific to your Gradle project | `TestFilter::isFailOnNoMatchingTests=false`
System properties | Properties that are passed to the Gradle runtime (JVM) | `systemProp.http.proxyHost=somehost.org`
Gradle properties | Properties that configure Gradle settings and the Java process that executes your build | `org.gradle.logging.level=quiet`
Environment variables | Properties that configure build behavior based on the environment | `JAVA_HOME`

## Priority for configurations

When configuring Gradle behavior, you can use these methods, but you must consider their priority.

The following table lists these methods in order of highest to lowest precedence (the first one wins):

Priority | Method | Location | Notes
--- | --- | --- | ---
1 | Command-line flags | Command line | Flags have precedence over properties and environment variables
2 | System properties | Project Root Dir | Stored in a `gradle.properties` file
3 | Gradle properties | `GRADLE_USER_HOME` Project Root Dir `GRADLE_HOME` | Stored in a `gradle.properties` file
4 | Environment variables | Environment | Sourced by the environment that executes Gradle

Here are all possible configurations of specifying the JDK installation directory in order of priority:

1. Command Line

       $ ./gradlew yourTask -Dorg.gradle.java.home=/path/to/your/java/home

2. Gradle Properties File

       org.gradle.java.home=/path/to/your/java/home

3. Environment Variable

       $ export JAVA_HOME=/path/to/your/java/home

## Project properties

Project properties are specific to your Gradle project, they are variables or configuration blocks defined in your build script or in the `project` object.

For example, the project property `myProperty` is created in a build file:

build.gradle

    ext {
        myProperty = findProperty('myProperty') ?: 'Hello, world!'
    }

    println "My property value: ${project.ext.myProperty}"

### Setting a project properties

You have three options to add project properties, listed in order of priority:

1. Command Line: You can add project properties directly to your Project object via the `-P` command line option.

       $ ./gradlew build -PmyProperty='Hi, world'

2. System Property: Gradle creates specially-named system properties for project properties which you can set using the `-D` command line flag or `gradle.properties` file. For the project property `prop`, the system property created is called `org.gradle.project.prop`.

       $ ./gradlew build -Dorg.gradle.project.myProperty='Hi, world'

   gradle.properties

       org.gradle.project.myProperty='Hi, world'

3. Environment Variables: You can set project properties with 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`.

       $ export ORG_GRADLE_PROJECT_myProperty='Hi, world'

   This feature is very useful when you don’t have admin rights to a continuous integration server and need to set property values that are not 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.

## Command-line flags

The command line interface and the available flags are described in its own section.

## System properties

System properties are variables set at the JVM level and accessible to the Gradle build process. System properties can be accessed using the `System` class in the build script.

### Setting system properties

You have two options to add system properties listed in order of priority:

1. Command Line: 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.

       $ ./gradlew build -Dgradle.wrapperUser=myuser

2. Gradle Properties File: You can also set system properties in `gradle.properties` files with the prefix `systemProp`.

   gradle.properties

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

### System properties reference

For a quick reference, the following are common system properties:

`gradle.wrapperUser=(myuser)`

  Specify username to download Gradle distributions from servers using HTTP Basic Authentication.

`gradle.wrapperPassword=(mypassword)`

  Specify password for downloading a Gradle distribution using the Gradle wrapper.

`gradle.user.home=(path to directory)`

  Specify the `GRADLE_USER_HOME` directory.

`https.protocols`

  Specify the supported TLS versions in a comma-separated format. e.g., `TLSv1.2,TLSv1.3`.

Additional Java system properties are listed here.

In a multi-project build, `systemProp` properties set in any project except the root will be ignored. Only the root project’s `gradle.properties` file will be checked for properties that begin with `systemProp`.

### Using system properties

The following examples demonstrate how to use system properties:

Example 1: Setting system properties with a `gradle.properties` file:

gradle.properties

    systemProp.system=gradlePropertiesValue

Example 2: Reading system properties at configuration time:

init.gradle.kts

    // Using the Java API
    println(System.getProperty("system"))

settings.gradle.kts

    // Using the Java API
    println(System.getProperty("system"))

    // Using the Gradle API, provides a lazy Provider<String>
    println(providers.systemProperty("system").get())

build.gradle.kts

    // Using the Java API
    println(System.getProperty("system"))

    // Using the Gradle API, provides a lazy Provider<String>
    println(providers.systemProperty("system").get())

init.gradle

    // Using the Java API
    println System.getProperty('system')

settings.gradle

    // Using the Java API
    println System.getProperty('system')

    // Using the Gradle API, provides a lazy Provider<String>
    println providers.systemProperty('system').get()

build.gradle

    // Using the Java API
    println System.getProperty('system')

    // Using the Gradle API, provides a lazy Provider<String>
    println providers.systemProperty('system').get()

Example 3: Reading system properties for consumption at execution time:

build.gradle.kts

    tasks.register<PrintValue>("printProperty") {
        // Using the Gradle API, provides a lazy Provider<String> wired to a task input
        inputValue = providers.systemProperty("system")
    }

build.gradle

    tasks.register('printProperty', PrintValue) {
        // Using the Gradle API, provides a lazy Provider<String> wired to a task input
        inputValue = providers.systemProperty('system')
    }

Example 4: Setting system properties from the command line `-D gradle.wrapperUser=username`:

    $ gradle -Dsystem=commandLineValue

## Gradle properties

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 be able 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 Gradle properties

You have two options to add Gradle properties listed in order of priority:

1. Command Line: Using the `-D` command-line option, you can pass a Gradle property:

       $ ./gradlew build -Dorg.gradle.caching.debug=false

2. Gradle Properties File: Place these settings into a `gradle.properties` file and commit it to your version control system.

   gradle.properties

       org.gradle.caching.debug=false

The final configuration considered by Gradle is a combination of all Gradle properties set on the command line and your `gradle.properties` files. If an option is configured in multiple locations, the first one found in any of these locations wins:

Priority | Method | Location | Details
--- | --- | --- | ---
1 | Command line interface | . | In the command line using `-D`.
2 | `gradle.properties` file | `GRADLE_USER_HOME` | Stored in a `gradle.properties` file in the `GRADLE_USER_HOME`.
3 | `gradle.properties` file | Project Root Dir | Stored in a `gradle.properties` file in a project directory, then its parent project’s directory up to the project’s root directory.
4 | `gradle.properties` file | `GRADLE_HOME` | Stored in a `gradle.properties` file in the `GRADLE_HOME`, the optional Gradle installation directory.

| The location of the `GRADLE_USER_HOME` may have been changed beforehand via the `-Dgradle.user.home` system property passed on the command line.

### Gradle properties reference

For reference, the following properties are common Gradle properties:

`org.gradle.caching=(true,false)`

  When set to `true`, Gradle will reuse task outputs from any previous build when possible, resulting in much faster builds.

  Default is `false`; the build cache is not enabled.

`org.gradle.caching.debug=(true,false)`

  When set to `true`, individual input property hashes and the build cache key for each task are logged on the console.

  Default is `false`.

`org.gradle.configuration-cache=(true,false)`

  Enables configuration caching. Gradle will try to reuse the build configuration from previous builds.

  Default is `false`.

`org.gradle.configureondemand=(true,false)`

  Enables incubating configuration-on-demand, where Gradle will attempt to configure only necessary projects.

  Default is `false`.

`org.gradle.console=(auto,plain,rich,verbose)`

  Customize console output coloring or verbosity.

  Default depends on how Gradle is invoked.

`org.gradle.continue=(true,false)`

  If enabled, continue task execution after a task failure, else stop task execution after a task failure.

  Default is `false`.

`org.gradle.daemon=(true,false)`

  When set to `true` the Gradle Daemon is used to run the build.

  Default is `true`.

`org.gradle.daemon.idletimeout=(# of idle millis)`

  Gradle Daemon will terminate itself after a specified number of idle milliseconds.

  Default is `10800000` (3 hours).

`org.gradle.debug=(true,false)`

  When set to `true`, Gradle will run the build with remote debugging enabled, listening on port 5005. Note that this is equivalent to adding `-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=5005` to the JVM command line and will suspend the virtual machine until a debugger is attached.

  Default is `false`.

`org.gradle.java.home=(path to JDK home)`

  Specifies the Java home for the Gradle build process. The value can be set to either a `jdk` or `jre` location; however, using a JDK is safer depending on what your build does. This does not affect the version of Java used to launch the Gradle client VM.

  You can also control the JVM used to run Gradle itself using the Daemon JVM criteria.

  Default is derived from your environment (`JAVA_HOME` or the path to `java`) if the setting is unspecified.

`org.gradle.jvmargs=(JVM arguments)`

  Specifies the JVM arguments used for the Gradle Daemon. The setting is particularly useful for configuring JVM memory settings for build performance. This does not affect the JVM settings for the Gradle client VM.

  Default is `-Xmx512m "-XX:MaxMetaspaceSize=384m"`.

`org.gradle.logging.level=(quiet,warn,lifecycle,info,debug)`

  When set to quiet, warn, info, or debug, Gradle will use this log level. The values are not case-sensitive.

  Default is `lifecycle` level.

`org.gradle.parallel=(true,false)`

  When configured, Gradle will fork up to `org.gradle.workers.max` JVMs to execute projects in parallel.

  Default is `false`.

`org.gradle.priority=(low,normal)`

  Specifies the scheduling priority for the Gradle daemon and all processes launched by it.

  Default is `normal`.

`org.gradle.projectcachedir=(directory)`

  Specify the project-specific cache directory. Defaults to `.gradle` in the root project directory."

  Default is `.gradle`.

`org.gradle.unsafe.isolated-projects=(true,false)`

  Enables project isolation, which enables configuration caching.

  Default is `false`.

`org.gradle.vfs.verbose=(true,false)`

  Configures verbose logging when watching the file system.

  Default is `false`.

`org.gradle.vfs.watch=(true,false)`

  Toggles watching the file system. When enabled, Gradle reuses information it collects about the file system between builds.

  Default is `true` on operating systems where Gradle supports this feature.

`org.gradle.warning.mode=(all,fail,summary,none)`

  When set to `all`, `summary`, or `none`, Gradle will use different warning type display.

  Default is `summary`.

`org.gradle.workers.max=(max # of worker processes)`

  When configured, Gradle will use a maximum of the given number of workers.

  Default is the number of CPU processors.

### Using Gradle properties

The following examples demonstrate how to use Gradle properties.

Example 1: Setting Gradle properties with a `gradle.properties` file:

gradle.properties

    gradlePropertiesProp=gradlePropertiesValue
    gradleProperties.with.dots=gradlePropertiesDottedValue

Example 2: Reading Gradle properties at configuration time:

settings.gradle.kts

    // Using the API, provides a lazy Provider<String>
    println(providers.gradleProperty("gradlePropertiesProp").get())

    // Using Kotlin delegated properties on `settings`
    val gradlePropertiesProp: String by settings
    println(gradlePropertiesProp)

build.gradle.kts

    // Using the API, provides a lazy Provider<String>
    println(providers.gradleProperty("gradlePropertiesProp").get())

    // Using Kotlin delegated properties on `project`
    val gradlePropertiesProp: String by project
    println(gradlePropertiesProp)

settings.gradle

    // Using the API, provides a lazy Provider<String>
    println providers.gradleProperty('gradlePropertiesProp').get()

    // Using Groovy dynamic names
    println gradlePropertiesProp
    println settings.gradlePropertiesProp

    // Using Groovy dynamic array notation on `settings`
    println settings['gradlePropertiesProp']

build.gradle

    // Using the API, provides a lazy Provider<String>
    println providers.gradleProperty('gradlePropertiesProp').get()

    // Using Groovy dynamic names
    println gradlePropertiesProp
    println project.gradlePropertiesProp

    // Using Groovy dynamic array notation on `project`
    println project['gradlePropertiesProp']

The Kotlin delegated properties are part of the Gradle Kotlin DSL. You need to explicitly specify the type as `String`. If you need to branch depending on the presence of the property, you can also use `String?` and check for `null`.

Note that using the dynamic Groovy names is impossible if a Gradle property has a dot in its name. You have to use the API or the dynamic array notation instead.

Example 3: Reading Gradle properties for consumption at execution time:

build.gradle.kts

    tasks.register<PrintValue>("printProperty") {
        // Using the API, provides a lazy Provider<String> wired to a task input
        inputValue = providers.gradleProperty("gradlePropertiesProp")
    }

build.gradle

    tasks.register('printProperty', PrintValue) {
        // Using the API, provides a lazy Provider<String> wired to a task input
        inputValue = providers.gradleProperty('gradlePropertiesProp')
    }

Example 4: Setting Gradle properties from the command line:

    $ gradle -DgradlePropertiesProp=commandLineValue

Note that initialization scripts can’t read Gradle properties directly. The earliest Gradle properties can be read in initialization scripts is on `settingsEvaluated {}`:

Example 5: Reading Gradle properties from initialization scripts:

init.gradle.kts

    settingsEvaluated {
        // Using the API, provides a lazy Provider<String>
        println(providers.gradleProperty("gradlePropertiesProp").get())

        // Using Kotlin delegated properties on `settings`
        val gradlePropertiesProp: String by this
        println(gradlePropertiesProp)
    }

init.gradle

    settingsEvaluated { settings ->
        // Using the API, provides a lazy Provider<String>
        println settings.providers.gradleProperty('gradlePropertiesProp').get()

        // Using Groovy dynamic names
        println settings.gradlePropertiesProp

        // Using Groovy dynamic array notation on `settings`
        println settings['gradlePropertiesProp']
    }

Properties declared in a `gradle.properties` file present in a subproject directory are only available to that project and its children.

## Environment variables

Gradle provides a number of environment variables, which are listed below.

### Setting environment variables

Let’s take an example that sets the $JAVA_HOME environment variable:

    $ set JAVA_HOME=C:\Path\To\Your\Java\Home   // Windows
    $ export JAVA_HOME=/path/to/your/java/home  // Mac/Linux

You can access environment variables as properties in the build script using the `System.getenv()` method:

    task printEnvVariables {
        doLast {
            println "JAVA_HOME: ${System.getenv('JAVA_HOME')}"
        }
    }

### Environment variables reference

The following environment variables are available for the `gradle` command:

`GRADLE_HOME`

  Installation directory for Gradle.

  Can be used to specify a local Gradle version instead of using the wrapper.

  You can add `GRADLE_HOME/bin` to your `PATH` for specific applications and use cases (such as testing an early release for Gradle).

`JAVA_OPTS`

  Used to pass JVM options and custom settings to the JVM.

`GRADLE_OPTS`

  Specifies JVM arguments to use when starting the Gradle client VM.

  The client VM only handles command line input/output, so one would rarely need to change its VM options.

  The actual build is run by the Gradle daemon, which is not affected by this environment variable.

`GRADLE_USER_HOME`

  Specifies the `GRADLE_USER_HOME` directory for Gradle to store its global configuration properties, initialization scripts, caches, log files and more.

  Defaults to `USER_HOME/.gradle` if not set.

`JAVA_HOME`

  Specifies the JDK installation directory to use for the client VM.

  This VM is also used for the daemon unless a different one is specified in a Gradle properties file with `org.gradle.java.home` or using the Daemon JVM criteria.

`GRADLE_LIBS_REPO_OVERRIDE`

  Overrides for the default Gradle library repository.

  Can be used to specify a default Gradle repository URL in `org.gradle.plugins.ide.internal.resolver`.

  Useful override to specify an internally hosted repository if your company uses a firewall/proxy.

### Using environment variables

The following examples demonstrate how to use environment variables.

Example 1: Reading environment variables at configuration time:

init.gradle.kts

    // Using the Java API
    println(System.getenv("ENVIRONMENTAL"))

settings.gradle.kts

    // Using the Java API
    println(System.getenv("ENVIRONMENTAL"))

    // Using the Gradle API, provides a lazy Provider<String>
    println(providers.environmentVariable("ENVIRONMENTAL").get())

build.gradle.kts

    // Using the Java API
    println(System.getenv("ENVIRONMENTAL"))

    // Using the Gradle API, provides a lazy Provider<String>
    println(providers.environmentVariable("ENVIRONMENTAL").get())

init.gradle

    // Using the Java API
    println System.getenv('ENVIRONMENTAL')

settings.gradle

    // Using the Java API
    println System.getenv('ENVIRONMENTAL')

    // Using the Gradle API, provides a lazy Provider<String>
    println providers.environmentVariable('ENVIRONMENTAL').get()

build.gradle

    // Using the Java API
    println System.getenv('ENVIRONMENTAL')

    // Using the Gradle API, provides a lazy Provider<String>
    println providers.environmentVariable('ENVIRONMENTAL').get()

Example 2: Reading environment variables for consumption at execution time:

build.gradle.kts

    tasks.register<PrintValue>("printValue") {
        // Using the Gradle API, provides a lazy Provider<String> wired to a task input
        inputValue = providers.environmentVariable("ENVIRONMENTAL")
    }

build.gradle

    tasks.register('printValue', PrintValue) {
        // Using the Gradle API, provides a lazy Provider<String> wired to a task input
        inputValue = providers.environmentVariable('ENVIRONMENTAL')
    }