Chapter 36. The Sonar Runner Plugin

The Sonar Runner plugin is the successor to the Sonar Plugin. It is currently incubating. The plugin is based on Sonar Runner 2.0, which makes it compatible with Sonar 2.11 and higher. Unlike the Sonar plugin, the Sonar Runner plugin works fine with Sonar 3.4 and higher.

To get started, apply the Sonar Runner plugin to the project to be analyzed.

apply plugin: "sonar-runner"

Assuming a local Sonar server with out-of-the-box settings is up and running, no further mandatory configuration is required. Execute gradle sonarRunner and wait until the build has completed, then open the web page indicated at the bottom of the Sonar Runner output. You should now be able to browse the analysis results.

Before executing the sonarRunner task, all tasks producing output to be analysed by Sonar need to be executed. Typically, these are compile tasks, test tasks, and code coverage tasks. To meet these needs, the plugins adds a task dependency from sonarRunner on test if the java plugin is applied. Further task dependencies can be added as needed.

The Sonar Runner plugin adds a SonarRunner extension to the project, which allows you to configure the Sonar Runner via key/value pairs known as Sonar properties. A typical base line configuration includes connection settings for the Sonar server and database.

sonarRunner {
    sonarProperties {
        property "sonar.host.url", "http://my.server.com"
        property "sonar.jdbc.url", "jdbc:mysql://my.server.com/sonar"
        property "sonar.jdbc.driverClassName", "com.mysql.jdbc.Driver"
        property "sonar.jdbc.username", "Fred Flintstone"
        property "sonar.jdbc.password", "very clever"
    }
}

For a complete list of standard Sonar properties, consult the Sonar documentation. If you happen to use additional Sonar plugins, consult their documentation.

Alternatively, Sonar properties can be set from the command line. See Section 35.6, “Configuring Sonar Settings from the Command Line” for more information.

The Sonar Runner plugin leverages information contained in Gradle's object model to provide smart defaults for many of the standard Sonar properties. The defaults are summarized in the tables below. Notice that additional defaults are provided for projects that have the java-base or java plugin applied. For some properties (notably server and database connection settings), determining a suitable default is left to the Sonar Runner.

The Sonar Runner is capable of analyzing whole project hierarchies at once. This yields a hierarchical view in the Sonar web interface, with aggregated metrics and the ability to drill down into subprojects. Analyzing a project hierarchy also takes less time than analyzing each project separately.

To analyze a project hierarchy, apply the Sonar Runner 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, like server and database connections settings, have to be configured in the sonarRunner block of this project. Any Sonar properties set on the command line also apply to this project.

sonarRunner {
    sonarProperties {
        property "sonar.host.url", "http://my.server.com"
        property "sonar.jdbc.url", "jdbc:mysql://my.server.com/sonar"
        property "sonar.jdbc.driverClassName", "com.mysql.jdbc.Driver"
        property "sonar.jdbc.username", "Fred Flintstone"
        property "sonar.jdbc.password", "very clever"
    }
}

Configuration shared between subprojects can be configured in a subprojects block.

subprojects {
    sonarRunner {
        sonarProperties {
            property "sonar.sourceEncoding", "UTF-8"
        }
    }
}

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

project(":project1") {
    sonarRunner {
        sonarProperties {
            property "sonar.language", "grvy"
        }
    }
}

To skip Sonar analysis for a particular subproject, set sonarRunner.skipProject to true.

project(":project2") {
    sonarRunner {
        skipProject = true
    }
}

By default, the Sonar Runner plugin 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.

sonarRunner {
    sonarProperties {
        properties["sonar.sources"] += sourceSets.custom.allSource.srcDirs
        properties["sonar.tests"] += sourceSets.integTest.allSource.srcDirs
    }
}

To analyze code written in a language other than Java, you'll need to set sonar.project.language accordingly. However, note that your Sonar server has to have the Sonar plugin that handles that programming language.

sonarRunner {
    sonarProperties {
        property "sonar.language", "grvy" // set language to Groovy
    }
}

As of Sonar 3.4, only one language per project can be analyzed. It is, however, possible to analyze a different language for each project in a multi-project build.

Let's take a closer look at the sonarRunner.sonarProperties {} 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 sonarProperties 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() method.

Because the sonarProperties 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.

Sonar Properties can also be set from the command line, 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 sonarRunner -Dsonar.host.url=http://sonar.mycompany.com -Dsonar.jdbc.password=myPassword -Dsonar.verbose=true

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.

Depending on project size, the Sonar Runner may require a lot of memory. For this and other (mainly isolation) reasons, it is desirable to execute the Sonar Runner in a separate process. This feature will be provided once Sonar Runner 2.1 has been released and adopted by the Sonar Runner plugin. Until then, the Sonar Runner is executed in the main Gradle process. See Section 20.1, “Configuring the build environment via gradle.properties” for how to manage memory settings for that process.

The Sonar Runner plugin adds the following tasks to the project.