SonarScanner for Gradle

The SonarScanner for Gradle provides an easy way to start the scan of a Gradle project.

The ability to execute the SonarScanner analysis via a regular Gradle task makes it available anywhere Gradle is available (developer build, CI server, etc.), without the need to manually download, setup, and maintain a SonarScanner CLI installation. The Gradle build already has much of the information needed for the SonarScanner to successfully analyze a project. By preconfiguring the analysis based on that information, the need for manual configuration is reduced significantly.

Prerequisites

• Gradle 5+
• Gradle 7+ and AGP 7+ for Android projects
• Java 11+

Bytecode created by javac compilation is required for Java analysis, including Android projects.

Configure the scanner

Installation is automatic, but certain global properties should still be configured. A good place to configure global properties is ~/.gradle/gradle.properties. Be aware that the scanner uses system properties so all properties should be prefixed by systemProp.

# gradle.properties
systemProp.sonar.host.url=http://localhost:9000

Analyzing

First, you need to activate the scanner in your build. Kotlin DSL is now the default choice for new Gradle builds. However, Groovy is still used by some developers. Apply the SonarQube plugin dependency to your build.gradle.kts file below:

plugins {
    id("org.sonarqube") version "4.2.1.3168"
}

sonar {
  properties {
    property("sonar.projectKey", "myProjectKey")
    property("sonar.organization", "myOrganization")
    property("sonar.host.url", "myHostUrl")
  }
}

If you still use Groovy DSL, it is supported for Gradle 2.1+. In that case, apply the SonarQube plugin dependency to your build.gradle file below:

plugins {
  id "org.sonarqube" version "4.2.1.3168"
}

sonar {
  properties {
    property "sonar.projectKey", "myProjectKey"
    property "sonar.organization", "myOrganization"
    property "sonar.host.url", "myHostUrl"
  }
}

Ensure that you declare the plugins in the correct sequence required by Gradle, that is, after the buildscript block in your build.gradle file. More details on Gradle - Plugin: org.sonarqube. 

Assuming a local SonarQube server with out-of-the-box settings is up and running, no further configuration is required.

You need to pass an authentication token using the sonar.login property in your command line or configure it as part of your gradle.properties file. Execute gradle sonar -Dsonar.login=yourAuthenticationToken and wait until the build has completed. Once passing your token and running an analysis, open the web page indicated at the bottom of the console output. Your analysis results should be available shortly after the CI-side analysis is complete.

Analyzing multi-project builds

To analyze a project hierarchy, apply the SonarQube plugin to the root project of the hierarchy. Typically (but not necessarily) this will be the root project of the Gradle build. Information pertaining to the analysis as a whole has to be configured in the sonar block of this project. Any properties set on the command line also apply to this project.

A configuration shared between subprojects can be configured in a subprojects block.

// build.gradle
subprojects {
    sonar {
        properties {
            property "sonar.sources", "src"
        }
    }
}

Project-specific information is configured in the sonar block of the corresponding project.

// build.gradle
project(":project1") {
    sonar {
        properties {
            property "sonar.branch", "Foo"
        }
    }}

To skip SonarScanner analysis for a particular subproject, set sonarqube.skipProject to true.

// build.gradle
project(":project2") {
    sonar {
        isSkipProject = true
    }
}

Task dependencies

All tasks that produce output that should be included in the SonarScanner analysis need to be executed before the sonar task runs. Typically, these are compile tasks, test tasks, and code coverage tasks.

Starting with v3.0 of the SonarScanner for Gradle, task dependencies are no longer added automatically. Instead, the SonarScanner plugin enforces the correct order of tasks with mustRunAfter. You need to be either manually run the tasks that produce output before sonarqube, or you can add a dependency to the build script:

// build.gradle
project.tasks["sonar"].dependsOn "anotherTask"

Sample project

A simple working example is available at this URL so you can check everything is correctly configured in your env:
https://github.com/SonarSource/sonar-scanning-examples/tree/master/sonar-scanner-gradle/gradle-basic

Analysis property defaults

The SonarScanner for Gradle uses information contained in Gradle's object model to provide smart defaults for most of the standard analysis parameters, as listed below.

Gradle defaults for standard Sonar properties

Additional defaults for all projects

Additional defaults for projects with Java-base or Java plugin applied

Additional default for Groovy projects

Additional defaults when JaCoCo plugin is applied

Additional defaults for Android projects 

Additional defaults are provided for Android projects (com.android.application, com.android.library, or com.android.test). By default the first variant of type debug will be used to configure the analysis. You can override the name of the variant to be used using the parameter androidVariant:

build.gradle
sonar {
    androidVariant 'fullDebug'
}

Passing manual properties / overriding defaults

The SonarScanner for Gradle adds a sonar extension to the project and its subprojects, which allows you to configure/override the analysis properties.

// in build.gradle
sonar {
    properties {
        property "sonar.exclusions", "**/*Generated.java"
    }
}

Sonar properties can also be set from the command line, or by setting a system property named exactly like the Sonar property in question. This can be useful when dealing with sensitive information (e.g. credentials), environment information, or for ad-hoc configuration.

gradle sonar -Dsonar.host.url=http://sonar.mycompany.com -Dsonar.verbose=true

While certainly useful at times, we recommend keeping the bulk of the configuration in a (versioned) build script, readily available to everyone. A Sonar property value set via a system property overrides any value set in a build script (for the same property). When analyzing a project hierarchy, values set via system properties apply to the root project of the analyzed hierarchy. Each system property starting with sonar. will be taken into account.

Analyzing custom source sets

By default, the SonarScanner for Gradle passes on the project's main source set as production sources, and the project's test source set as test sources. This works regardless of the project's source directory layout. Additional source sets can be added as needed.

// build.gradle
sonar {
    properties {
        properties["sonar.sources"] += sourceSets.custom.allSource.srcDirs
        properties["sonar.tests"] += sourceSets.integTest.allSource.srcDirs
    }
}

Advanced topics

More on configuring SonarQube properties

Let's take a closer look at the sonar.properties block. As we have already seen in the examples, the property method allows you to set new properties or override existing ones. Furthermore, all properties that have been configured up to this point, including all properties preconfigured by Gradle, are available via the properties accessor.

Entries in the properties map can be read and written with the usual Groovy syntax. To facilitate their manipulation, values still have their “idiomatic” type (File, List, etc.). After the sonar.properties block has been evaluated, values are converted to Strings as follows: Collection values are (recursively) converted to comma-separated Strings, and all other values are converted by calling their toString methods.

Because the sonar.properties block is evaluated lazily, properties of Gradle's object model can be safely referenced from within the block, without having to fear that they have not yet been set.

Troubleshooting

If you get a java.lang.OutOfMemoryError: Metaspace

Increase the metaspace size in your gradle.properties file:

org.gradle.jvmargs=-XX:MetaspaceSize=512M -XX:MaxMetaspaceSize=512M