Android Code Signing

import { Image } from 'astro:assets'; import { Code, Tabs, TabItem } from '@astrojs/starlight/components'; import BuildGradleFiletree from '@assets/distribute/sign/build-gradle-kts-filetree.png';

To publish on the Play Store, you need to sign your app with a digital certificate.

Android App Bundles and APKs must be signed before being uploaded for distribution.

Google also provides an additional signing mechanism for Android App Bundles distributed in the Play Store. See the official Play App Signing documentation for more information.

Creating a keystore and upload key

Android signing requires a Java Keystore file that can be generated using the official keytool CLI:

keytool -genkey -v -keystore ~/upload-keystore.jks -keyalg RSA -keysize 2048 -validity 10000 -alias upload

keytool -genkey -v -keystore $env:USERPROFILE\upload-keystore.jks -storetype JKS -keyalg RSA -keysize 2048 -validity 10000 -alias upload

This command stores the upload-keystore.jks file in your home directory. If you want to store it elsewhere, change the argument you pass to the -keystore parameter.

:::tip

• The keytool command might not be in your PATH. You may find it installed in the JDK that is installed with Android Studio:

:::

:::caution[Security Warning]

Keep the keystore file private; don't check it into public source control!

:::

See the official documentation for more information.

Configure the signing key

Create a file named [project]/src-tauri/gen/android/keystore.properties that contains a reference to your keystore:

password=<password defined when keytool was executed>
keyAlias=upload
storeFile=<location of the key store file, such as /Users/<user name>/upload-keystore.jks or C:\\Users\\<user name>\\upload-keystore.jks>

:::caution[Security Warning] Keep the keystore.properties file private; don't check it into public source control. :::

You will usually generate this file in your CI/CD platform. The following snippet contains an example job step for GitHub Actions:

- name: setup Android signing
  run: |
    cd src-tauri/gen/android
    echo "keyAlias=${{ secrets.ANDROID_KEY_ALIAS }}" > keystore.properties
    echo "password=${{ secrets.ANDROID_KEY_PASSWORD }}" >> keystore.properties
    base64 -d <<< "${{ secrets.ANDROID_KEY_BASE64 }}" > $RUNNER_TEMP/keystore.jks
    echo "storeFile=$RUNNER_TEMP/keystore.jks" >> keystore.properties

In this example the keystore was exported to base64 with base64 -i /path/to/keystore.jks and set as the ANDROID_KEY_BASE64 secret.

Configure Gradle to use the signing key

Configure gradle to use your upload key when building your app in release mode by editing the [project]/src-tauri/gen/android/app/build.gradle.kts file.

:::tip

There are multiple different build.gradle.kts files in a typical Android project. If there is no buildTypes block you're looking at the wrong file. The one you need is in the app/ directory relative to the keystore file from the prior step.

:::

1. Add the needed import at the beginning of the file:

   kotlinCopy

   import java.io.FileInputStream
   

2. Add the release signing config before the buildTypes block:

   kotlinCopy

   signingConfigs {
       create("release") {
           val keystorePropertiesFile = rootProject.file("keystore.properties")
           val keystoreProperties = Properties()
           if (keystorePropertiesFile.exists()) {
               keystoreProperties.load(FileInputStream(keystorePropertiesFile))
           }
   
           keyAlias = keystoreProperties["keyAlias"] as String
           keyPassword = keystoreProperties["password"] as String
           storeFile = file(keystoreProperties["storeFile"] as String)
           storePassword = keystoreProperties["password"] as String
       }
   }
   
   buildTypes {
       ...
   }
   

3. Use the new release signing config in the release config in buildTypes block:

   kotlinCopy

   buildTypes {
       getByName("release") {
           signingConfig = signingConfigs.getByName("release")
       }
   }
   

Release builds of your app will now be signed automatically.