Android build settings that works in both IDE and CI server

android-build-settings.md

What is this for

• Auto-generated version number for release builds
• No need to include keystore / password in repository
• The code should still build with no extra configuration

How it works

• Version code / number are generated from the commit itself
• Version / sign settings are injected as environment variables
• When these settings are not present, failback to default ones silently

build.gradle

// read env variable as string or integer
def env = { System.getenv it }
def envInt = { Integer.parseInt(env(it)) }

android {
    defaultConfig {
        if (env("ANDROID_VERSION_CODE")) {
            versionCode envInt("ANDROID_VERSION_CODE")
            versionName env("ANDROID_VERSION_NAME")
        } else {
            // failback versions, so we don't have to set env-varables in IDE.
            versionCode 1
            versionName "1.0"
        }
    }
}

if (env("ANDROID_SIGN_APK"))
// only apply when setted
android {
    signingConfigs {
        releaseSigning {
            storeFile file(env("ANDROID_KEYSTORE_PATH"))
            storePassword env("ANDROID_KEYSTORE_PASS")
            keyAlias env("ANDROID_KEY_ALIAS")
            keyPassword env("ANDROID_KEY_PASS")
        }
    }

    buildTypes {
        release {
            signingConfig signingConfigs.releaseSigning
        }
    }
}

jenkins-build-script.sh

#!/bin/bash

# sets (local-specific settings / sign settings / computed attributes) on a CI server (I'm using jenkins)

# DO NOT commit this file and sign keys into repository

# JDK & SDK
export ANDROID_HOME=/somewhere/android-sdk-linux
export JAVA_HOME=/somewhere/jdk1.8.0_65

# SIGN
export ANDROID_KEYSTORE_PATH=/somewhere/keys.jks
export ANDROID_SIGN_APK=yes
export ANDROID_KEYSTORE_PASS=secret
export ANDROID_KEY_ALIAS=secret
export ANDROID_KEY_PASS=secret

# versionCode: number of commits that are reachable from here
# *supposedly* monotonically increasing for each release build
export ANDROID_VERSION_CODE="$(git rev-list HEAD --count)"
# versionName: first 8 chars in commit SHA1
export ANDROID_VERSION_NAME="${GIT_COMMIT:0:8}"

exec sh gradlew clean aR