How to sign release apk with gradle

Whenever I prepare my APK for the release - I used to do the following steps:

  1. Copy keystore to the project directory
  2. Copy gradle.properties into the project directory with keystore name, alias and password defined
  3. Copy some code from some blog that would load the properties and set up the signing
  4. Finally, do gradle build

But why not to move the boilderplate out of build.gradle?

Helper signing script

I wrote a tiny helper script that can be included into the projects:

def signingProperties = "signing.properties"
def signingKeys = [
	storeFile     : {x -> file(x)},
	storePassword : {x -> x},
	keyAlias      : {x -> x},
	keyPassword   : {x -> x},
]

// Find signing.properties in the project root, or in $HOME/.gradle
def f = ["${rootDir}/${signingProperties}", "${gradle.gradleUserHomeDir}/${signingProperties}"].find { file(it).exists() }

if (f) {
	logger.info "Loading signing properties from ${f}"
	def props = new Properties()
	props.load(new FileInputStream(f))

	// For each property apply it to the release signing config
	signingKeys.any { k, fn ->
		if (!props.containsKey(k)) {
			logger.error "Missing property ${k}"
			android.buildTypes.release.signingConfig = null
			return true
		}
		android.signingConfigs.release[k] = fn(props[k]);
		return
	}
} else {
	logger.info "Missing ${signingProperties} file"
	android.buildTypes.release.signingConfig = null
}

It scans for the signing.propeties file in the project directory and in the gradle home directory, then it parses the properties and configures the build.

usage

Now I do the following.

Create signing.properties in my $HOME/.gradle (once for all projects):

storeFile=my.keystore
keyAlias=myalias
storePassword=mypassword
keyPassword=mypassword2

Put my.keystore into $HOME/.gradle (once for all projects).

Edit build.gradle to use release singing config (most likely it is already done did it the app has been signed in the past):

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

Finally, I include the script above. I simply use the github link:

	apply from: 'https://raw.github.com/trikita/gradle-android-signing/master/gradle-android-signing.gradle'

Done. One ‘apply from’ line and signing just works.

You may try it, too. Sources are available on github, so please file an issue or a pull request if something it not working.

Posted on 2015-08-09

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