gradle configuration using a local properties files to load credentials

build.gradle

//...
def keystorePropertiesFile = file("../keystore.properties");
def keystoreProperties = new Properties()
keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
android {
    signingConfigs {
        release {
            storeFile = file(keystoreProperties['storeFile'])
            storePassword = keystoreProperties['storePassword']
            keyAlias = keystoreProperties['keyAlias']
            keyPassword = keystoreProperties['keyPassword']
        }
        debug {
            storeFile = file(keystoreProperties['storeFile'])
            storePassword = keystoreProperties['storePassword']
            keyAlias = keystoreProperties['keyAlias']
            keyPassword = keystoreProperties['keyPassword']
        }
    }
    // ...
}