Configure Signing Settings

Configure the build.gradle with signing configuration

You can define the signing configuration to sign the apk in the build.gradle file.

You can define:

storeFile : the keystore file
storePassword: the keystore password
keyAlias: a key alias name
keyPassword: A key alias password

You have to define the signingConfigs block to create a signing configuration:

android {
    signingConfigs {

        myConfig {
            storeFile file("myFile.keystore")
            storePassword "myPasswork"
            keyAlias "aKeyAlias"
            keyPassword "myAliasPassword"
        }
    }
    //....
}

Then you can assign it to one or more build types.

android {

    buildTypes {
        release {
            signingConfig signingConfigs.myConfig
        }
    }
}

Define the signing configuration in an external file

You can define the signing configuration in an external file as a signing.properties in the root directory of your project.

For example you can define these keys (you can use your favorite names):

STORE_FILE=myStoreFileLocation    
STORE_PASSWORD=myStorePassword
KEY_ALIAS=myKeyAlias
KEY_PASSWORD=mykeyPassword

Then in your build.gradle file:

android {

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

Then you can introduce some checks to avoid gradle issues in the build process.

//------------------------------------------------------------------------------
// Signing
//------------------------------------------------------------------------------
def Properties props = new Properties()
def propFile = file('../signing.properties')
if (propFile.canRead()) {

    if (props != null && props.containsKey('STORE_FILE') && props.containsKey('STORE_PASSWORD') &&
            props.containsKey('KEY_ALIAS') && props.containsKey('KEY_PASSWORD')) {

        android.signingConfigs.release.storeFile = file(props['STORE_FILE'])
        android.signingConfigs.release.storePassword = props['STORE_PASSWORD']
        android.signingConfigs.release.keyAlias = props['KEY_ALIAS']
        android.signingConfigs.release.keyPassword = props['KEY_PASSWORD']
    } else {
        android.buildTypes.release.signingConfig = null
    }
} else {
    android.buildTypes.release.signingConfig = null
}

Define the signing configuration setting environment variables

You can store the signing information setting environment variables.
These values can be accessed with System.getenv("<VAR-NAME>")

In your build.gradle you can define:

signingConfigs {
    release {
        storeFile file(System.getenv("KEYSTORE"))
        storePassword System.getenv("KEYSTORE_PASSWORD")
        keyAlias System.getenv("KEY_ALIAS")
        keyPassword System.getenv("KEY_PASSWORD")
    }
}

Define signing configuration in a separate gradle file

The simplest and cleanest way to add an external configuration is through a separate Gradle file

build.gradle

apply from: './keystore.gradle'
android{
    signingConfigs {
        release {
            storeFile file(keystore.storeFile)
            storePassword keystore.storePassword
            keyAlias keystore.keyAlias
            keyPassword keystore.keyPassword
        }
    }
}

keystore.gradle

ext.keystore = [
    storeFile    : "/path/to/your/file",
    storePassword: 'password of the store',
    keyAlias     : 'alias_of_the_key',
    keyPassword  : 'password_of_the_key'
]

The keystore.gradle file can exist anywhere in your file system, you can specify its location inside the apply from: '' at the top of your gradle file or at the end of your main project build.gradle file.

Typically its a good idea to ignore this file from version control system such as git if its located inside your repo.

It is also a good idea to provide a sample keystore.gradle.sample which developers entering the project would rename and populate on their development machine. This file would always be contained inside the repo at the correct location.