Posted by Doug Stevenson, Developer Advocate

Starting today, the Android SDKs for Google Play services and Firebase will be using a new build and versioning scheme. This may require some changes to the way you build your Android app, so be sure to read here thoroughly to get all the details.

Here's a quick summary of what's new in these SDKs:

All dependencies now use semantic versioning.

Each dependency may be updated individually, removing the need to upgrade them all simultaneously in your app.

Each dependency has a faster cycle for bug fixes and new features.

Beginning with version 15 of all Play services and Firebase libraries, version numbers adhere to the semantic versioning scheme. As you know, semver is an industry standard for versioning software components, so you can expect that version number changes for each library indicate the amount of change in the library.

Each Maven dependency matching com.google.android.gms:play-services-* and com.google.firebase:firebase-* is no longer required to have the same version number in order to work correctly at build time and at run time. You will be able to upgrade each dependency independently from each other. As such, a common pattern for specifying the shared version number for Play and Firebase dependencies in Gradle builds will no longer work as expected. The pattern (now anti-pattern) looks like this:

buildscript { ext { play_version = '15.0.0' } } dependencies { // DON'T DO THIS!! // The following use of the above buildscript property is no longer valid. implementation "com.google.android.gms:play-services-auth:${play_version}" implementation "com.google.firebase:firebase-auth:${play_version}" implementation "com.google.firebase:firebase-firestore:${play_version}" }

The above Gradle configuration defines a buildscript property called play_version with the version of the Play and Firebase SDKs, and uses that to declare dependencies. This pattern has been helpful to keep all the dependency versions together, as previously required. However, this pattern no longer applies starting with version 15 for each library. Each dependency that you use may now be at different versions. You can expect that individual library updates may not be released at the same time - they may be updated independently.

In order to support this change in versioning, the Play services Gradle plugin has been updated. If you're using this plugin, it appears like this at the bottom of build.gradle in your app module:

apply plugin: 'com.google.gms.google-services'

Here is what has changed in this plugin:

It checks for compatible versions of Play and Firebase libraries. This is similar to enabling the failOnVersionConflict() ResolutionStrategy.

ResolutionStrategy. Licensing information is embedded in each individual build artifact. If you use the oss-licenses plugin to manage license requirements, you should update it to the latest.

The first version of this plugin that works with the new versioning system is 3.3.0. When working with the new versions of Play and Firebase libraries, it should be added to your buildscript classpath dependencies as follows:

classpath 'com.google.gms:google-services:3.3.0'

If you're not using this plugin, but you still want strict version checking of your dependencies, you can apply this new Gradle plugin instead:

apply plugin: 'com.google.android.gms.strict-version-matcher-plugin'

In order to use this plugin, you will also need to add the following to your buildscript classpath, obtained from Google's Maven Repository:

classpath 'com.google.android.gms:strict-version-matcher-plugin:1.0.0'

If you're not using Android Studio 3.1 to develop your app, you will need to upgrade in order to get the correct version checking behavior within the IDE. Get the newest version of Android Studio here.

With these changes in place, you are now able to adopt new versions of the various SDKs more freely, without a strict requirement to update everything at once. It also enables the development teams for each SDK to ship fixes and enhancements more quickly. Going forward, you can track the releases for Play services SDKs and Firebase SDKs with the provided links.