Signing your app

Android requires that all apps be digitally signed with a certificate before they can be installed. To install a release version of your app on a device it will need to signed. Thankfully signing an app is relatively straightforward.

Step 1: Generate a private key

To generate a private key enter the following into your terminal, making sure to replace myexample with the desired keystore name, and examplekey with the desired alias. You will then be prompted to answer some questions in order to generate the key.

keytool -genkey -v -keystore myexample.keystore -alias examplekey -keyalg RSA -keysize 2048 -validity 10000

Step 2: Update the app build.gradle

Add the signingConfig block to your app's build.gradle file. Set the storeFile field to the location of your keystore. Set the storePassword, keyAlias, keyPassword fields to their respective values. Finally set the signingConfig field in the buildTypes release block to signingConfigs.release.

android {
    ...
    signingConfigs {
        release {
            storeFile file("/Users/anders/myexample.keystore")
            storePassword "password"
            keyAlias "examplekey"
            keyPassword "password"
        }
    }

    buildTypes {
        release {
            ...
            signingConfig signingConfigs.release
            ...
        }
    }
    ...
}

Keeping your signing credentials secure

If you use a hosted git repository service like GitHub you might not want to commit your keystore and password details for security reasons. You can do this by using a gradle.properties file.

Step 1: Create a gradle.properties file

Create a file named gradle.properties in the root level of your project directory.

Step 2: Specify the fields in the gradle.properties file

Add the myExampleKeystore, myExampleKeystorePassword, myExampleKeyAlias and myExampleKeyPassword fields to the gradle.properties file, and set them to their respective values.

myExampleKeystore=/Users/anders/Projects/myexample.keystore
myExampleKeystorePassword=password
myExampleKeyAlias=myexample
myExampleKeyPassword=password

Step 3: Update the app build.gradle

Change the values of the storeFile , storePassword, keyAlias and keyPassword to reference the values stored in the gradle.properties file

    signingConfigs {
        release {
            storeFile file(myExampleKeystore)
            storePassword myExampleKeystorePassword
            keyAlias myExampleKeyAlias
            keyPassword myExampleKeyPassword
        }
    }

Step 4: Update .gitignore

Add gradle.properties to your projects .gitignore file. So that it doesn't get tracked by git. This ensures that your signing credentials will only be stored locally on your machine.

Check out this project for an example of how to sign your app's release build.