AOSP host integration guide

The Android Open Source Project (AOSP) Automotive App Host is a part of the Car App Library used by third-party (3P) developers to enable apps for Android Automotive. The App Host is a system app that allows 3P car apps to render OEM-styled user interface (UI) components on its behalf.

To run 3P apps, both the 3P app and the AOSP Automotive App Host must be installed:

Automotive App Host provides 3P apps with a a set of UI templates and components optimized for vehicles, including capabilities like usability and safety.
OEMs can style these UI templates and components.
The result? 3P apps are visually well-integrated into the infotainment system of the OEM.

This page explains how to generate the AOSP Automotive App Host from the Gradle project in the ub-automotive branch and then how to integrate the AOSP Automotive App Host into car targets.

Check out the code

To check out the unbundled code:

Run the following command:

repo init -u https://android.googlesource.com/platform/manifest -b ub-automotive-master
repo sync -j4

To learn more about working with AOSP source code, see Initialize a Repo client.
Install Android Studio.

Create the AOSP host APK

Check out ub-automotive and then open the Gradle project under packages/apps/Car/Templates/Host.
To configure the project with the Android SDK, configure your project's local.properties file. You can find the path under Android SDK Settings in Android Studio.
```
sdk.dir=${path_to_android_sdk_location}
```
Create the host APK as a typical Gradle project. For example, run the gradle command:
```
./gradlew :app:assembleDebug
```
The APK file is located in:
```
packages/apps/Car/Templates/Host/app/build/outputs/apk/debug/app-debug.apk
```

Embed the AOSP host

Create a new Android.mk file to include the following content:

LOCAL_PATH := $(my-dir)
################## Start of AOSPHost target ##################
include $(CLEAR_VARS)
LOCAL_MODULE := CarAOSPHost
LOCAL_LICENSE_KINDS := legacy_notice
LOCAL_LICENSE_CONDITIONS := notice
LOCAL_MODULE_OWNER := google
LOCAL_SRC_FILES := AOSPHost.apk
LOCAL_MODULE_CLASS := APPS
LOCAL_MODULE_TAGS := optional
LOCAL_MODULE_SUFFIX := $(COMMON_ANDROID_PACKAGE_SUFFIX)
LOCAL_BUILT_MODULE_STEM := package.apk
LOCAL_CERTIFICATE := PRESIGNED
LOCAL_PRIVILEGED_MODULE := true
LOCAL_PRODUCT_MODULE := true
LOCAL_DEX_PREOPT := false
include $(BUILD_PREBUILT)

Rename the app-debug.apk to AOSPHost.apk and put the APK in the same folder as Android.mk.
Add the CarAOSPHost module to your targets as PRODUCT_PACKAGES:
```
PRODUCT_PACKAGES += \
   CarAOSPHost \
```

Add the permissions config

Create a file called com.android.car.templates.host.xml to contain the following:

<permissions>
    <!-- Rename the package to com.android.car.templates.host -->
    <privapp-permissions package="com.android.car.templates.host">
        <!-- To be able to display activities in the cluster -->
        <permission name="android.car.permission.CAR_DISPLAY_IN_CLUSTER" />

        <!-- To be able to show navigation state (turn by turn directions) in the cluster.-->
        <permission name="android.car.permission.CAR_NAVIGATION_MANAGER" />

        <!-- To be considered a system-approved host -->
        <permission name="android.car.permission.TEMPLATE_RENDERER" />
    </privapp-permissions>

    <!-- Declare support for templated applications. -->
    <feature name="android.software.car.templates_host" />
</permissions>

In your target, add the config file to your targets:

PRODUCT_COPY_FILES += \
    <the file root>/com.android.car.templates.host.xml:$(TARGET_COPY_OUT_VENDOR)/etc/permissions/com.android.car.templates.host.xml

Build the target

When you build the target, the host is installed and permission is granted:

      …
      android.car.permission.CAR_NAVIGATION_MANAGER: granted=true
      android.car.permission.CAR_DISPLAY_IN_CLUSTER: granted=true
      android.car.permission.TEMPLATE_RENDERER: granted=true
      …

Note: The permission android.car.permission.TEMPLATE_RENDERER is only available after Android API level 32.

Test the integration

To build and install the samples, see this GitHub project, car-samples/car_app_library.