Google services Gradle plugin and JSON config file

As part of adding Firebase to your Android project, you need to add the google-services Gradle plugin and a google-services.json configuration file to your project.

If you add Firebase to your Android project using the Firebase console, the Management REST API, or the Firebase CLI, you must manually add the Gradle plugin and JSON config file to your project. However, if you use the Firebase Assistant for Android Studio, these tasks are automatically done for you during setup.

Add the Gradle plugin

You add the Google services Gradle plugin (google-services) to your build.gradle file:

dependencies {
    classpath 'com.google.gms:google-services:4.5.0'
    // ...
}

The Google services Gradle plugin has two main functions:

  • Processes the google-services.json config file and produces Android resources that can be used in your app's code.

  • Adds dependencies for basic libraries required for the services you have enabled. This step requires that you apply the Google services Gradle plugin in your app/build.gradle file, like so:
    apply plugin: 'com.google.gms.google-services'

    You can see the result of this step by running ./gradlew :app:dependencies.

Add the JSON config file

The google-services.json config file is generally placed in the app/ directory (at the root of the Android Studio app module). As of version 2.2.0 the plugin supports build type and product flavor specific JSON files. All of the following directory structures are valid:

// dogfood and release are build types.
app/
    google-services.json
    src/dogfood/google-services.json
    src/release/google-services.json
    ...

When product flavors are in use these more complicated directory structures are also valid.

// free and paid are product flavors.
app/
    google-services.json
    src/dogfood/paid/google-services.json
    src/release/free/google-services.json
    ...

How the JSON config file is processed

The google-services.json config file has the following basic structure:

{
  "project_info": {...},
  "client": [...],
}

The project_info object contains general information about your project, while each member of the client array contains information about the clients (Android apps) that you have added to the project.

When processing the JSON file for your Android app, the plugin only uses the client object that matches your package name (for the current build type) based on the following logic:

  • For each member of the client array, the plugin checks the value of client_info/android_client_info/package_name. If the package name matches this value, it returns the member object.

  • If none of the members of client match the package name, the plugin throws an exception.

The remainder of this document uses YOUR_CLIENT to refer to the member of the client array determined by the logic described above.

Production of XML files

The main result of the JSON processing is to produce two XML files that you can reference as Android resources in your code. The following are examples of each file:

  • app/build/generated/res/google-services/{build_type}/values/values.xml

    <?xml version="1.0" encoding="utf-8"?>
<resources>

    <! -- Present in all applications -->
    <string name="google_app_id" translatable="false">1:1035469437089:android:73a4fb8297b2cd4f</string>

    <! -- Present in applications with the appropriate services configured -->
    <string name="gcm_defaultSenderId" translatable="false">1035469437089</string>
    <string name="default_web_client_id" translatable="false">337894902146-e4uksm38sne0bqrj6uvkbo4oiu4hvigl.apps.googleusercontent.com</string>
    <string name="ga_trackingId" translatable="false">UA-65557217-3</string>
    <string name="firebase_database_url" translatable="false">https://example-url.firebaseio.com</string>
    <string name="google_api_key" translatable="false">AIzbSyCILMsOuUKwN3qhtxrPq7FFemDJUAXTyZ8</string>
    <string name="google_crash_reporting_api_key" translatable="false">AIzbSyCILMsOuUKwN3qhtxrPq7FFemDJUAXTyZ8</string>
    <string name="project_id" translatable="false">mydemoapp</string>

</resources>

  • app/build/generated/res/google-services/{flavor}/{build_type}/xml/global_tracker.xml

    <?xml version="1.0" encoding="utf-8"?>
<resources>
    <string name="ga_trackingId" translatable="false">UA-65557218-3</string>
</resources>

Values in the XML files

Every value in the XML files is present in the google-services.json config file at the locations listed below. If your Android project has some configuration that prevents you from using the google-services Gradle plugin, you can safely recreate the XML files manually using these values.

  • google_app_id

    YOUR_CLIENT/client_info/mobilesdk_app_id

  • gcm_defaultSenderId

    project_info/project_number

  • default_web_client_id

    YOUR_CLIENT/oauth_client/client_id (client_type == 3)

  • ga_trackingId

    YOUR_CLIENT/services/analytics-service/analytics_property/tracking_id

  • firebase_database_url

    project_info/firebase_url

  • google_api_key

    YOUR_CLIENT/api_key/current_key

  • google_crash_reporting_api_key

    YOUR_CLIENT/api_key/current_key

  • project_id

    project_info/project_id

Troubleshooting

When building, I get the following error message: File google-services.json is missing from module root folder. The Google Services Plugin cannot function without it.

The Firebase console will help you download the google-services.json config file.

After you've downloaded the google-services.json config file, copy it into the app/ folder of your Android Studio project, or into the app/src/{build_type} folder if you're using multiple build types.

I can't find the symbols like R.string.gcm_defaultSenderId or R.xml.global_tracker.

Make sure the package name in your build.gradle file matches the package name you entered when creating the google-services.json file. If you are not sure, run through the getting started flow again and get a new JSON file.