An extremely simple plugin for exporting data from gradle script into properties file.

export_plugin.gradle

/**
 * Created by amak on 8/19/16.
 *
 * An extremely simple plugin for exporting data from gradle script into properties file.
 * It's very useful for CI systems: turn your gradle script variables into environment variables.
 *
 * Plugin adds an extension exportExt for variables you want to export:
 *
 * exportExt {
 *     prop "version", myProjectVersion
 *     prop "projectName", "myProjectName"
 *     prop "NoDeploy", true
 * }
 *
 * Data is exported by calling exportProps task. Default filename is "build/build.properties" in your root project
 * You can specify different filename with command line argument -PexportFile="path/to/your/file"
 *
 * Example bash script:
 *
 * #!/bin/bash
 *
 *  PROPS_FILE = "path/to/your/file"
 * ./gradlew exportProps -PexportFile=$PROPS_FILE #Exporting properties
 *
 * source $PROPS_FILE #importing variables
 *
 * mkdir /my/deploy/path/$version
 *
 * #End of bash script
 *
 */

class ExportDataPlugin implements Plugin<Project> {

    @Override
    void apply(Project target) {
        target.extensions.create(ExportExtension.NAME, ExportExtension)
        target.tasks.create(ExportPropsTask.NAME, ExportPropsTask)
    }
}

class ExportExtension {
    static String NAME = "exportExt"
    Properties props = new Properties()

    def prop(String key, String value) {
        this.props.setProperty(key, value)
    }
}

class ExportPropsTask extends DefaultTask {
    static NAME = "exportProps"
    ExportExtension extension

    ExportPropsTask() {
        project.afterEvaluate {
            extension = project.extensions."${ExportExtension.NAME}"
        }
    }

    @TaskAction
    void exec() {
        File file = project.hasProperty('exportFile') ? new File(project.exportFile) : new File(project.rootProject.buildDir, "build.properties")
        println "Creating file ${file.absolutePath} with project info..."
        file.getParentFile().mkdirs()
        def writer = new FileWriter(file)
        extension.props.store(writer, "Build info")
    }
}

apply plugin:ExportDataPlugin