• Runs a MiniApp on an Android emulator or connected device


ern run-android


--baseComposite <compositePath>

  • Git or File System path, to the custom Composite repository (refer to the custom Composite documentation for more information).

--descriptor, -d

  • complete native application descriptor

--dev [true|false]

  • Enable or disable React Native dev support


  • Optional extra configuration specific to local container and runner

  • Override the android build config during local container generation and runner project by passing androidConfig attributes

    • As a json string

      For example --extra '{"androidConfig": {"androidGradlePlugin": "3.2.1","buildToolsVersion": "28.0.3","compileSdkVersion": "28","gradleDistributionVersion": "4.6","minSdkVersion": "19","sourceCompatibility": "VERSION_1_8","supportLibraryVersion": "28.0.0","targetCompatibility": "VERSION_1_8","targetSdkVersion": "28"}}'

    • As a file path

      For example --extra /Users/username/my-container-config.json

      In that case, the configuration will be read from the file.

    • As a Cauldron file path

      For example --extra cauldron://config/container/my-container-config.json

      In that case, the configuration will be read from the file stored in Cauldron.

      For this way to work, the file must exist in Cauldron (you can add a file to the cauldron by using the [ern cauldron add file] command).


  • Host or ip to launch the local packager on (default: localhost)

--launchFlags <string>

  • Extra options passed to am start command when launching the application (correspond to the Launch Flags in Run/Debug Configurations of application in Android Studio, as can be seen on screenshot below)

  • Make sure to use = on the command line to provide this option, and keep the string in quotes. For example --launchFlags="--es aKey aStringValue --ei anotherKey 1"


  • Name of the MiniApp to launch when starting the Runner application

  • If you are running the command from the MainApp directory, only specify name of the MiniApp (Not the path).


  • One or more MiniApps to combine in the Runner Container


  • Port on which the local packager should listen on (default: 8081)


  • Use the previously selected device to avoid prompt

JavaScript engine

By default Electrode Native will run the MiniApp with a Container that uses JavaScriptCore engine. If you'd rather like to run the MiniApp with Hermes engine, you should add the following inside the ern object of the MiniApp package.json :

 "androidConfig": {
  "jsEngine": "hermes"


  • You can launch the MiniApp located in the current working directory or on a connected Android device or running emulator if available. If a connected Android device is not available, the command prompts you to select an emulator to launch from the list of installed emulator images.

  • The first time you run this command from within a MiniApp directory, it generates an Android directory containing the Android runner application project. If the Android folder already exists (it is not the first run of the ern run-android command for this MiniApp), the existing runner project is used.

  • After the runner project is generated, you can safely make native code modifications to it, knowing that the next time the ern run-android command is issued, the project and your changes will remain.

  • If you want to regenerate the runner project from scratch, remove the Android directory.

  • The miniapp can be any Yarn package descriptor, including Git or other file system path schemes.

  • The ern run-android command is the ern equivalent of the react-native run-android command.

  • If you are running the command from the MainApp directory, only specify name of the MiniApp (Not the path) in the --mainMiniAppName option.

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