React Native - Generating Signed APK

Step 1: Running keytool

Windows

Open Command Prompt

gotto C:\Program Files\Java\jdkx.x.x_x\bin

and run as administrator.

keytool -genkeypair -v -storetype PKCS12 -keystore my-upload-key.keystore -alias my-key-alias -keyalg RSA -keysize 2048 -validity 10000

macOS

To find your JDK bin folder on macOS, run the following command:

/usr/libexec/java_home

Upon completion, the directory of the JDK will look like this:

/Library/Java/JavaVirtualMachines/jdkX.X.X_XXX.jdk/Contents/Home

Use the cd command to navigate to that directory, and then run the keytool command with sudo permissions.

sudo keytool -genkey -v -keystore my-upload-key.keystore -alias my-key-alias -keyalg RSA -keysize 2048 -validity 10000

Step 2: Setting up Gradle variables

1. You will need to place the my-upload-key.keystore file under your project folder's Android/app directory.

2. Edit the file ~/.gradle/gradle.properties or android/gradle.properties, and add the following (replace ***** with the correct keystore password, alias and key password),

MYAPP_UPLOAD_STORE_FILE=my-upload-key.keystore
MYAPP_UPLOAD_KEY_ALIAS=my-key-alias
MYAPP_UPLOAD_STORE_PASSWORD=*****
MYAPP_UPLOAD_KEY_PASSWORD=*****

Step 3: Adding signing configuration to your Gradle configuration

...
android {
    ...
    defaultConfig { ... }
    signingConfigs {
        release {
            if (project.hasProperty('MYAPP_UPLOAD_STORE_FILE')) {
                storeFile file(MYAPP_UPLOAD_STORE_FILE)
                storePassword MYAPP_UPLOAD_STORE_PASSWORD
                keyAlias MYAPP_UPLOAD_KEY_ALIAS
                keyPassword MYAPP_UPLOAD_KEY_PASSWORD
            }
        }
    }
    buildTypes {
        release {
            ...
            signingConfig signingConfigs.release
        }
    }
}
...

Step 4: Generating the release AAB

npx react-native build-android --mode=release

Step 5: Testing the release build

npm run android -- --mode="release"

ProGuard

Create proguard-rules.txt: Place this file in android/app/build/outputs/apk/release.

Add ProGuard rules: Adapt the rules to your specific app's needs by following the general guidance.

Configure Gradle: Update android/app/build.gradle with the appropriate ProGuard settings

buildTypes {
    release {
        minifyEnabled true
        useProguard true
        proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.txt'
    }
}

Difference AAB vs apk

There are a few key differences between AAB (Android App Bundle) and APK (Android application package) file formats for distributing Android apps:

ABB (Android App Bundle)

The AAB is mainly used for publishing apps to app stores like Google Play. The app cannot be installed directly on a device.

The AAB consists of modular components that are separated according to the device configuration (code, resources, assets).

For each user, Google Play generates an optimized APK based on their device requirements from the AAB.

Reducing data usage and storage consumption by delivering only necessary components to users.

Enhances flexibility by allowing apps to add and remove features dynamically after installation.

Reduced update sizes: Only updated components are delivered, which reduces update sizes.

APK (Android application package)

An APK file allows apps to be installed directly onto devices or sideloaded.

The APK file includes all components of the app, regardless of the device. In contrast to an optimized AAB, it could be larger.

There is no need to process app store APKs or manage split APKs.

Compatibility: Will work on older devices or platforms that do not support AAB.

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