Signing Android Apps

March 3, 2022·

As an Android Engineer, I have to sign Android apps whenever making a public release. The steps are quite simple and well documented on the official website. However the one thing that always comes up how do you provide your signing credentials and keystore file. Lets find out!

There 2 common ways this can be done:

Using ENV vars (Recommended)

Inside your ~/.zshrc or ~/.bashrc file, declare the key value pairs as shown below:

Note: For CI, declare key-value pair under secrets section

export KEYSTORE_FILE_PATH = "/Users/your_user/App_Directory/keystore_file.keystore"
export KEYSTORE_PASSWORD = "********"
export KEY_ALIAS = "key_alias"
export KEY_PASSWORD = "************"

Then inside your app module’s build.gradle file, you can reference it as shown below:

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

Using local.properties file

Inside your local.properties file, declare the key value pairs as shown below:

storeFile=../keystore.jks
storePassword=example
keyAlias=example
keyPassword=example

Note: keystore.jks file is the Keystore file that is expected to be placed inside the root directory of your project.

Next create a signing.gradle file at the root of your project and add the below code in it:

def keystorePropertiesFile = rootProject.file("local.properties")

if (keystorePropertiesFile.exists()) {
	// Load the properties
	def keystoreProperties = new Properties()
	keystoreProperties.load(new FileInputStream(keystorePropertiesFile))
	android {
		signingConfigs {
			if (keystorePropertiesFile.exists()) {
				release {
					keyAlias keystoreProperties['keyAlias']
					keyPassword keystoreProperties['keyPassword']
					storeFile file(keystoreProperties['storeFile'])
					storePassword keystoreProperties['storePassword']
				}
			}
		}

		buildTypes {
			release {
				if (keystorePropertiesFile.exists()) {
					signingConfig signingConfigs.release
				}
			}
		}
	}
} else {
	println("Filename: keystore.properties")
	println("Error: File does not exists")
	println("Solution: Create a keystore.properties file with valid details under keystore directory at the root of your project")
}

Now in order to use this signing.gradle config in your app, open the build.gradle file for app module and add the the below line of code just above the android {} block:


apply from: "$rootProject.projectDir/signing.gradle"

// android { ... }

Thats all!

In both cases, simply sync your project and you should be able to sign your APK file by executing ./gradlew assembleRelease 🎉

Last updated on September 30, 2024

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