Publishing your Flutter App to Google Playstore

23 Mar 2020

Reading time ~5 minutes

Table Of Contents

Update App Manifest
Update Package Identifier
Generate Launcher Icons
Signing the App
Reference the Keystore in the App
Configure signing in gradle
Review Build Configuration
Build the App Bundle
Test App Bundle
- Offline
Upload App to Playstore
References

Update App Manifest

Review the default App Manifest file, AndroidManifest.xml, located in <app dir>/android/app/src/main and verify that the values are correct

[1] Edit the android:label in the application tag to reflect the final name of the app.

<application
        android:name="io.flutter.app.FlutterApplication"
        android:label="Covid-19 Tracker"
        android:icon="@mipmap/ic_launcher">

[2] Add the required app permissions to the manifest file. For Example, if your app needs internet access then you need to add below permission to your manifest file.

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.rharshad.covid_19_tracker">

    <!-- Add the android.permission.INTERNET permission if your application code needs Internet access -->
    <uses-permission android:name="android.permission.INTERNET"/>

    <application
        android:name="io.flutter.app.FlutterApplication"
        android:label="Covid-19 Tracker"
        android:icon="@mipmap/ic_launcher">

Update Package Identifier

Update your package name as required as it is unique across the app playstore.

Let’s say we need the package to be named as com.rharshad.covid_19_tracker instead of the default package name given by flutter com.example.flutter_complete_guide.

Then, package names need to be updated in below files:

[1] AndroidManifest.xml, located in <app dir>/android/app/src/main

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.rharshad.covid_19_tracker">

[2] AndroidManifest.xml, located in <app dir>/android/app/src/debug

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.rharshad.covid_19_tracker">

[3] MainActivity.kt, located in <app dir>/android/app/src/main/kotlin/...

package com.rharshad.covid_19_tracker

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

[4] applicationId, located in <app dir>/android/app/build.gradle

defaultConfig {
  applicationId "com.rharshad.covid_19_tracker"
  minSdkVersion 16
  targetSdkVersion 28
  versionCode flutterVersionCode.toInteger()
  versionName flutterVersionName
  testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
}

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Generate Launcher Icons

flutter_launcher_icons package simplifies the task of updating your Flutter app’s launcher icon.

Fully flexible, allowing you to choose what platform you wish to update the launcher icon for and if you want, the option to keep your old launcher icon in case you want to revert back sometime in the future.

Update your pubspec.yaml with flutter_launcher_icons as a dev dependency:

dev_dependencies:
  flutter_test:
    sdk: flutter
  flutter_launcher_icons: ^0.7.4

Add the icon path to pubspec.yaml file:

flutter_icons:
  android: true
  image_path: "images/covid-19-icon.png"

Run the command to generate the launcher icons in <app dir>/android/app/src/main/res folders.

$ flutter pub run flutter_launcher_icons:main
Android minSdkVersion = 16
Creating default icons Android
Overwriting the default Android launcher icon with a new icon

Signing the App

To publish on the Play Store, you need to give your app a digital signature.

Get keytool path by running flutter doctor -v command:

$ flutter doctor -v

[√] Flutter (Channel stable, v1.12.13+hotfix.8, on Microsoft Windows [Version 10.0.17763.1098], locale en-US)    • Flutter version 1.12.13+hotfix.8 at C:\flutter_windows_v1.12.13+hotfix.8-stable\flutter
    • Framework revision 0b8abb4724 (6 weeks ago), 2020-02-11 11:44:36 -0800
    • Engine revision e1e6ced81d
    • Dart version 2.7.0


[√] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at C:\Users\Harshad\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 29.0.3
    • ANDROID_HOME = C:\Users\Harshad\AppData\Local\Android\sdk
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b04)
    • All Android licenses accepted.

Keytool will be available at path shown by Java binary at: in the above output.

Create a keystore by running below command:

<keytool_path>/keytool -genkey -v -keystore <keystore_path>/<file_name>.jks -storetype JKS -keyalg RSA -keysize 2048 -validity 10000 -alias key

Sample Output:

Note: Add quotes around space separated names in file paths

$ C:\/"Program Files/"\Android\/"Android Studio/"\jre/bin/keytool -genkey -v -keystore c:/Users/Harshad/test.jks -storetype JKS -keyalg RSA -keysize 2048 -validity 10000 -alias key

Enter keystore password:  random
Re-enter new password: random
What is your first and last name?
  [Unknown]:  Harshad Ranganathan
What is the name of your organizational unit?
  [Unknown]:
What is the name of your organization?
  [Unknown]:
What is the name of your City or Locality?
  [Unknown]:
What is the name of your State or Province?
  [Unknown]:
What is the two-letter country code for this unit?
  [Unknown]:
Is CN=Harshad Ranganathan, OU=Unknown, O=Unknown, L=Unknown, ST=Unknown, C=Unknown correct?
  [no]:  yes

Generating 2,048 bit RSA key pair and self-signed certificate (SHA256withRSA) with a validity of 10,000 days
        for: CN=Harshad Ranganathan, OU=Unknown, O=Unknown, L=Unknown, ST=Unknown, C=Unknown
Enter key password for <key>
        (RETURN if same as keystore password):
[Storing c:/Users/Harshad/test.jks]

Warning:
The JKS keystore uses a proprietary format. It is recommended to migrate to PKCS12 which is an industry standard format using "keytool -importkeystore -srckeystore c:/Users/Harshad/test.jks -destkeystore c:/Users/Harshad/test.jks -deststoretype pkcs12".

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Reference the Keystore in the App

Create a file named <app dir>/android/key.properties that contains a reference to your keystore:

Give the password, alias & keystore path which you had given earlier to generate the keystore.

storePassword=random
keyPassword=random
keyAlias=key
storeFile=c:/Users/Harshad/key.jks

This file should not be checked into source control as the keystore password needs to be private.

Add key.properties to your .gitignore file inside <app dir>/android to exclude the file.

Configure signing in gradle

Configure signing for your app by editing the <app dir>/android/app/build.gradle file.

Add this code before the android {...} block:

def keystoreProperties = new Properties()
def keystorePropertiesFile = rootProject.file('key.properties')
if (keystorePropertiesFile.exists()) {
    keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
}

Replace the buildTypes block with below code:

signingConfigs {
  release {
    keyAlias keystoreProperties['keyAlias']
    keyPassword keystoreProperties['keyPassword']
    storeFile keystoreProperties['storeFile'] ? file(keystoreProperties['storeFile']) : null
    storePassword keystoreProperties['storePassword']
  }
}
buildTypes {
  release {
    signingConfig signingConfigs.release
  }
}

Review Build Configuration

[1] Check the version in your pubspec.yaml file to verify it’s correct.

version: 1.0.0+1

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Build the App Bundle

Run below command to create the release bundle.

The release bundle for your app is created at <app dir>/build/app/outputs/bundle/release/app.aab.

Note: R8 is the new code shrinker from Google, and it’s enabled by default when you build a release APK or AAB.

$ flutter build appbundle
Running Gradle task 'bundleRelease'...
Running Gradle task 'bundleRelease'... Done                       106.1s
√ Built build\app\outputs\bundle\release\app-release.aab (18.2MB)

Test App Bundle

Offline

[1] Download bundletool jar from https://github.com/google/bundletool/releases

[2] Generate apks for your app bundle by running below command:

java -jar bundletool-all-0.13.3.jar build-apks --bundle=C:/Github/covid_19_tracker/build/app/outputs/bundle/release/app-release.aab \
--output=C:/Github/covid_19_tracker/build/app/outputs/bundle/release/app-release.apks \
--ks=c:/Users/Harshad/key.jks --ks-pass=pass:random --key-pass=pass:random --ks-key-alias=key \
--connected-device

where

Param	Value
–bundle	Path to your app bundle
–output	Path to output apks files
–ks	Path to keystore file
–ks-pass=pass:	Keystore password
–key-pass=pass:	Password for signing key
–connected-device	Instructs bundletool to build APKs that target the configuration of a connected device.

[3] Deploy the apks to the connected device.

java -jar bundletool-all-0.13.3.jar install-apks \
--apks=C:/Github/covid_19_tracker/build/app/outputs/bundle/release/app-release.apks 

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Upload App to Playstore

[1] Sign up for Google Play Console.

[2] Create a new application by giving a title.

[3] In the Store Listing section fill up the mandatory details, upload icons, screenshots, give proper categorization and content ratings.

[4] In the App releases section, add your app bundle to the production track and give a release name.

[5] Before you submit your app for review, fill up the other mandatory sections such as Content rating, App Content and Pricing & Distribution.

Once you submit your app for review it will be pending publication until your app gets reviewed.

References

https://flutter.dev/docs/deployment/android

https://developer.android.com/studio/command-line/bundletool#generate_apks