Android Auto Backup and Data Restore: What Developers Must Know

onCreate()

<!-- res/xml/backup_rules.xml -->
<full-backup-content>
    <!-- Include these files -->
    <include domain="database" path="app_database" />
    <include domain="sharedpref" path="user_settings" />
    
    <!-- Exclude these files -->
    <exclude domain="sharedpref" path="auth_prefs" />
    <exclude domain="sharedpref" path="fcm_token" />
    <exclude domain="file" path="cache" />
    <exclude domain="file" path="temp" />
</full-backup-content>

AndroidManifest.xml

<application
    android:allowBackup="true"
    android:fullBackupContent="@xml/backup_rules">

<!-- res/xml/data_extraction_rules.xml -->
<data-extraction-rules>
    <cloud-backup>
        <include domain="database" path="app_database" />
        <exclude domain="sharedpref" path="auth_prefs" />
    </cloud-backup>
    
    <device-transfer>
        <!-- What transfers via device-to-device transfer (different from cloud) -->
        <include domain="database" path="app_database" />
    </device-transfer>
</data-extraction-rules>

<application
    android:dataExtractionRules="@xml/data_extraction_rules">

Application.onCreate()

class App : Application() {
    override fun onCreate() {
        super.onCreate()
        
        // Validate restored data
        val restoredVersion = prefs.getInt("data_version", 0)
        val currentVersion = BuildConfig.VERSION_CODE
        
        if (restoredVersion > 0 && restoredVersion < currentVersion) {
            migrateRestoredData(restoredVersion, currentVersion)
        }
        
        // Mark current version
        prefs.edit().putInt("data_version", currentVersion).apply()
    }
    
    private fun migrateRestoredData(fromVersion: Int, toVersion: Int) {
        // Handle schema or data format changes
        // Room migration handles database changes automatically
        // Custom SharedPreferences migration goes here
    }
}

# Trigger a backup
adb shell bmgr backup com.yourapp.package
adb shell bmgr run

# Clear app data (simulate new device install)
adb shell pm clear com.yourapp.package

# Restore from backup
adb shell bmgr restore com.yourapp.package

# Reinstall and check state

// Use EncryptedSharedPreferences — it's encrypted at rest and in backup
val masterKey = MasterKey.Builder(context)
    .setKeyScheme(MasterKey.KeyScheme.AES256_GCM)
    .build()

val encryptedPrefs = EncryptedSharedPreferences.create(
    context,
    "encrypted_settings",
    masterKey,
    EncryptedSharedPreferences.PrefKeyEncryptionScheme.AES256_SIV,
    EncryptedSharedPreferences.PrefValueEncryptionScheme.AES256_GCM
)

EncryptedSharedPreferences

class TaskBackupAgent : BackupAgentHelper() {
    override fun onCreate() {
        // Back up specific SharedPreferences
        SharedPreferencesBackupHelper(
            this,
            "user_settings",
            "app_config"
        ).also { addHelper("prefs", it) }
        
        // Back up specific files
        FileBackupHelper(
            this,
            "tasks_export.json"
        ).also { addHelper("files", it) }
    }
    
    override fun onRestoreFinished() {
        // Called when restore is complete
        // Validate and migrate restored data here
        validateRestoredDatabase()
    }
}

<application android:backupAgent=".backup.TaskBackupAgent">

@Composable
fun BackupSettingsSection() {
    Column {
        Text("Data Backup", style = MaterialTheme.typography.titleMedium)
        Text(
            "Your tasks are automatically backed up to your Google account. " +
            "Install the app on a new device and sign in to restore your data.",
            style = MaterialTheme.typography.bodySmall,
            color = MaterialTheme.colorScheme.onSurfaceVariant
        )
        TextButton(onClick = { /* Open backup settings */ }) {
            Text("Manage backup settings")
        }
    }
}