Android app version from GIT tag

25. 04. 2018

Tired by incrementing app version with every release? This article shows how to set app version by git tag. Every release needs to be tagged, so it makes perfect sense to extract current app version from the last one.

Tag version in git

First lets define some standardized git tag name. In rest of article we use this format:

{stage}/{x}.{y}.{z}

where {stage} is something like alpha, beta, release and {x}, {y}, {z} are major, minor and build versions. Make your test git tag by calling:

git tag release/0.2.1 -a

Your last commit is now tagged as release with version 0.2.1, you can see more info about last release tag in current branch this way:

git describe --match 'release/*' --long

This is the end of GIT part!

Read version from gradle

We use the command-line git tools to read last tag matching particular variant as mentioned above. The result is simple function for reading and parsing version from git tag:

def getVersionTag = { variant ->
     def stdout
    try {
        stdout = new ByteArrayOutputStream()
        exec {
             commandLine "git", "describe", "--match", "${variant}/*", "--long"
             standardOutput = stdout
        }
        def longTag = stdout.toString().trim()

        return longTag.substring(longTag.indexOf('/') + 1, longTag.indexOf('-'))
     } catch (exception) {
        return "0.0.1";
     }
}

Result of this method is in our example “0.2.1”, the version without variant prefix. This is good form for version name, but we have to convert it to version code:

def getVersionCode = { tag ->
    def parts = tag.tokenize('.')
    if(parts.size() != 3 || parts[1].length() > 2 || parts[2].length() > 2) {
        throw new RuntimeException("Invalid version tag \"${tag}\", format \"x.y.z\" expected.")
    }
    if(parts[1].length() == 1) {
        parts[1] = "0" + parts[1]
    }
    if(parts[2].length() == 1) {
        parts[2] = "0" + parts[2]
    }
    return Integer.parseInt(parts[0] + parts[1] + parts[2])
}

def getVersionName = { tag ->
    return tag
}

Use git tag version for all variants

Last step is applying version name and code to all build variants. Put following piece of script to the end of android section in your gradle file:

android {
     applicationVariants.all { variant ->
        def versionTag = getVersionTag(variant.buildType.name)
        def myVersionCode = getVersionCode(versionTag)
        def myVersionName = getVersionName(versionTag)

        println variant.name + "[" + myVersionCode + ", " + myVersionName + "]"

        variant.mergedFlavor.versionName = myVersionName;
        variant.mergedFlavor.versionCode = myVersionCode;
    }
}

Complete build.gradle script

We are done, enjoy this gradle script:

apply plugin: 'com.android.application'

def getVersionTag = { variant ->
    def stdout
    try {
        stdout = new ByteArrayOutputStream()
        exec {
            commandLine "git", "describe", "--match", "${variant}/*", "--long"
            standardOutput = stdout
        }
        def longTag = stdout.toString().trim()

        return longTag.substring(longTag.indexOf('/') + 1, longTag.indexOf('-'))
    } catch (exception) {
        return "0.0.1";
    }
}

def getVersionCode = { tag ->
    def parts = tag.tokenize('.')
    if(parts.size() != 3 || parts[1].length() > 2 || parts[2].length() > 2) {
        throw new RuntimeException("Invalid version tag \"${tag}\", format \"x.y.z\" expected.")
    }
    if(parts[1].length() == 1) {
        parts[1] = "0" + parts[1]
    }
    if(parts[2].length() == 1) {
        parts[2] = "0" + parts[2]
    }
    return Integer.parseInt(parts[0] + parts[1] + parts[2])
}

def getVersionName = { tag ->
    return tag
}

android {

    compileSdkVersion 22
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "net.skoumal.gittagversion"
        minSdkVersion 14
        targetSdkVersion 22
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

     applicationVariants.all { variant ->
         def versionTag = getVersionTag(variant.buildType.name)
         def myVersionCode = getVersionCode(versionTag)
         def myVersionName = getVersionName(versionTag)

         println variant.name + "[" + myVersionCode + ", " + myVersionName + "]"

         variant.mergedFlavor.versionName = myVersionName;
         variant.mergedFlavor.versionCode = myVersionCode;
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:22.1.1'
}