expo-gradle-ext-vars

expo-gradle-ext-vars

By Transistor Software, creators of React Native Background Geolocation

A simple Expo Config Plugin for appending Android ext vars to the android/build.gradle. ext vars are a common Android method for configuring project-wide, global configuration properties which can be shared by other plugins in order to avoid dependency conflicts.

A common usage of ext vars is to align Google / AndroidX dependency version across different plugins using the same dependencies. For example:

dependencies {
    implementation "androidx.appcompat:appcompat:${rootProject.ext.appCompatVersion}"
    implementation "com.google.android.gms:play-services-location:${rootProject.ext.playServicesLocationVersion}"
}

Example Result: android/build.gradle

import org.apache.tools.ant.taskdefs.condition.Os

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    ext {
+       // @generated begin expo-gradle-ext-vars - expo prebuild (DO NOT MODIFY) sync-8c85b9ad3863726565f7eff0645ac3f5c56ce733
+       googlePlayServicesLocationVersion = "20.0.0"
+       appCompatVersion = "1.4.2"
+       // @generated end expo-gradle-ext-vars

        buildToolsVersion = findProperty('android.buildToolsVersion') ?: '31.0.0'
        minSdkVersion = Integer.parseInt(findProperty('android.minSdkVersion') ?: '21')
        compileSdkVersion = Integer.parseInt(findProperty('android.compileSdkVersion') ?: '31')
        targetSdkVersion = Integer.parseInt(findProperty('android.targetSdkVersion') ?: '31')
        if (findProperty('android.kotlinVersion')) {
            kotlinVersion = findProperty('android.kotlinVersion')
        }
        frescoVersion = findProperty('expo.frescoVersion') ?: '2.5.0'

        if (System.properties['os.arch'] == 'aarch64') {
            // For M1 Users we need to use the NDK 24 which added support for aarch64
            ndkVersion = '24.0.8215888'
        } else {
            // Otherwise we default to the side-by-side NDK version from AGP.
            ndkVersion = '21.4.7075529'
        }
    }
 }

Installation

npx expo install expo-gradle-ext-vars

Usage

Add the following block to your Expo app's app.json.

:warning: The variables below are only an example. You should only provide variables as prescribed by some other plugin you're installing.

{
  "expo": {
    "plugins": [
      [
        "expo-gradle-ext-vars", {
          "googlePlayServicesLocationVersion": "20.0.0",
          "appCompatVersion": "1.4.2"
        }
      ]
    ]
 }

After adding the plugin, run:

npx expo prebuild

Changelog

[0.1.3] — 2025-05-05

• Fix for Expo 53 Android. The ext { } block no longer exists by default. First check if exists and append empty ext { } block if not.