react-native/react.gradle

import org.apache.tools.ant.taskdefs.condition.Os

def config = project.hasProperty("react") ? project.react : [];

def cliPath = config.cliPath ?: "node_modules/react-native/local-cli/cli.js"
def bundleAssetName = config.bundleAssetName ?: "index.android.bundle"
def entryFile = config.entryFile ?: "index.android.js"
def bundleCommand = config.bundleCommand ?: "bundle"
def reactRoot = file(config.root ?: "../../")
def inputExcludes = config.inputExcludes ?: ["android/**", "ios/**"]
def bundleConfig = config.bundleConfig ? "${reactRoot}/${config.bundleConfig}" : null ;


afterEvaluate {
    android.applicationVariants.all { def variant ->
        // Create variant and target names
        def targetName = variant.name.capitalize()
        def targetPath = variant.dirName

        // React js bundle directories
        def jsBundleDir = file("$buildDir/generated/assets/react/${targetPath}")
        def resourcesDir = file("$buildDir/generated/res/react/${targetPath}")

        def jsBundleFile = file("$jsBundleDir/$bundleAssetName")

        // Additional node and packager commandline arguments
        def nodeExecutableAndArgs = config.nodeExecutableAndArgs ?: ["node"]
        def extraPackagerArgs = config.extraPackagerArgs ?: []

        def currentBundleTask = tasks.create(
            name: "bundle${targetName}JsAndAssets",
            type: Exec) {
            group = "react"
            description = "bundle JS and assets for ${targetName}."

            // Create dirs if they are not there (e.g. the "clean" task just ran)
            doFirst {
                jsBundleDir.deleteDir()
                jsBundleDir.mkdirs()
                resourcesDir.deleteDir()
                resourcesDir.mkdirs()
            }

            // Set up inputs and outputs so gradle can cache the result
            inputs.files fileTree(dir: reactRoot, excludes: inputExcludes)
            outputs.dir jsBundleDir
            outputs.dir resourcesDir

            // Set up the call to the react-native cli
            workingDir reactRoot

            // Set up dev mode
            def devEnabled = !(config."devDisabledIn${targetName}"
                || targetName.toLowerCase().contains("release"))

            def extraArgs = extraPackagerArgs;

            if (bundleConfig) {
                extraArgs = extraArgs.clone()
                extraArgs.add("--config");
                extraArgs.add(bundleConfig);
            }

            if (Os.isFamily(Os.FAMILY_WINDOWS)) {
                commandLine("cmd", "/c", *nodeExecutableAndArgs, cliPath, bundleCommand, "--platform", "android", "--dev", "${devEnabled}",
                    "--reset-cache", "--entry-file", entryFile, "--bundle-output", jsBundleFile, "--assets-dest", resourcesDir, *extraArgs)
            } else {
                commandLine(*nodeExecutableAndArgs, cliPath, bundleCommand, "--platform", "android", "--dev", "${devEnabled}",
                    "--reset-cache", "--entry-file", entryFile, "--bundle-output", jsBundleFile, "--assets-dest", resourcesDir, *extraArgs)
            }

            enabled config."bundleIn${targetName}" ||
                config."bundleIn${variant.buildType.name.capitalize()}" ?:
                targetName.toLowerCase().contains("release")
        }

        // Expose a minimal interface on the application variant and the task itself:
        variant.ext.bundleJsAndAssets = currentBundleTask
        currentBundleTask.ext.generatedResFolders = files(resourcesDir).builtBy(currentBundleTask)
        currentBundleTask.ext.generatedAssetsFolders = files(jsBundleDir).builtBy(currentBundleTask)

        // registerGeneratedResFolders for Android plugin 3.x
        if (variant.respondsTo("registerGeneratedResFolders")) {
            variant.registerGeneratedResFolders(currentBundleTask.generatedResFolders)
        } else {
            variant.registerResGeneratingTask(currentBundleTask)
        }
        variant.mergeResources.dependsOn(currentBundleTask)

        // packageApplication for Android plugin 3.x
        def packageTask = variant.hasProperty("packageApplication")
            ? variant.packageApplication
            : tasks.findByName("package${targetName}")

        def resourcesDirConfigValue = config."resourcesDir${targetName}"
        if (resourcesDirConfigValue) {
            def currentCopyResTask = tasks.create(
                name: "copy${targetName}BundledResources",
                type: Copy) {
                group = "react"
                description = "copy bundled resources into custom location for ${targetName}."

                from resourcesDir
                into file(resourcesDirConfigValue)

                dependsOn(currentBundleTask)

                enabled currentBundleTask.enabled
            }

            packageTask.dependsOn(currentCopyResTask)
        }

        def currentAssetsCopyTask = tasks.create(
            name: "copy${targetName}BundledJs",
            type: Copy) {
            group = "react"
            description = "copy bundled JS into ${targetName}."

            if (config."jsBundleDir${targetName}") {
                from jsBundleDir
                into file(config."jsBundleDir${targetName}")
            } else {
                into ("$buildDir/intermediates")
                into ("assets/${targetPath}") {
                    from jsBundleDir
                }

                // Workaround for Android Gradle Plugin 3.2+ new asset directory
                into ("merged_assets/${targetPath}/merge${targetName}Assets/out") {
                    from jsBundleDir
                }
            }

            // mergeAssets must run first, as it clears the intermediates directory
            dependsOn(variant.mergeAssets)

            enabled currentBundleTask.enabled
        }

        packageTask.dependsOn(currentAssetsCopyTask)
    }
}