Config variables for React Native apps

Module to expose config variables to your javascript code in React Native, supporting both iOS and Android.

Bring some 12 factor love to your mobile apps!

Usage

Declare config variables in .env:

API_URL=https://myapi.com
GOOGLE_MAPS_API_KEY=abcdefgh

Then access from your app:

import Config from 'react-native-config'

Config.API_URL  // 'https://myapi.com'
Config.GOOGLE_MAPS_API_KEY  // 'abcdefgh'

Android

Config variables set in .env are available to your Java classes via BuildConfig:

public HttpURLConnection getApiClient() {
    URL url = new URL(BuildConfig.API_URL);
    // ...
}

You can also read them from your Gradle configuration:

signingConfigs {
    release {
        storeFile file(project.env.get("RELEASE_STORE_FILE"))
        storePassword project.env.get("RELEASE_STORE_PASSWORD")
        keyAlias project.env.get("RELEASE_KEY_ALIAS")
        keyPassword project.env.get("RELEASE_KEY_PASSWORD")
    }
}

And use them to configure libraries in AndroidManifest.xml and others:

<meta-data
  android:name="com.google.android.geo.API_KEY"
  android:value="@string/GOOGLE_MAPS_API_KEY" />

iOS

Xcode support is missing; variables declared in .env. can be consumed from React Native apps in iOS via Config, but not from plist files.

Different environments

Save config for different environments in different files: .env.staging, .env.production, etc.

By default react-native-config will read from .env, but you can change it when building or releasing your app.

Android

To pick which file to use in Android, just set ENVFILE before building/running your app. For instance:

$ ENVFILE=.env.staging react-native run-android

iOS

Support for Xcode is still a bit experimental – but at this moment the recommendation is to create a new scheme for your app, and configure it to use a different env file.

To create a new scheme, open your app in Xcode and then:

• Click the current app scheme (button with your app name next to the stop button)
• Click "Manage Schemes..."
• Select your current scheme (the one on top)
• Click the settings gear below the list and select "Duplicate"
• Give it a proper name on the top left. For instance: "Myapp (staging)"

To make a scheme use a different env file, on the manage scheme window:

• Expand the "Build" settings on left
• Click "Pre-actions", and under the plus sign select "New Run Script Action"
• Fill in with this script on the dark box, replacing .env.staging for the file you want:

echo ".env.staging" > /tmp/envfile

This is still experimental and obviously a bit dirty – let me know if you have better ideas on this front!

Setup

Install the package:

$ npm install react-native-config --save

Then follow the platform-specific instructions below:

iOS

Link the library with rnpm:

$ rnpm link react-native-config

Android

Include this module in android/settings.gradle:

include ':react-native-config'
include ':app'

project(':react-native-config').projectDir = new File(rootProject.projectDir,
  '../node_modules/react-native-config/android')

Apply a plugin and add dependency to your app build, in android/app/build.gradle:

// 2nd line, add a new apply:
apply from: project(':react-native-config').projectDir.getPath() + "/dotenv.gradle"

// down below, add new compile:
dependencies {
    ...
    compile project(':react-native-config')
}

Change your main activity to add a new package, in android/app/src/main/.../MainActivity.java:

import com.lugg.ReactNativeConfig.ReactNativeConfigPackage; // add import

public class MainActivity extends ReactActivity {
    // ...

    @Override
    protected List<ReactPackage> getPackages() {
        return Arrays.<ReactPackage>asList(
            new MainReactPackage(),
            new ReactNativeConfigPackage() // add package
        );
    }

Advanced Setup

In android/app/build.gradle, if you use applicationIdSuffix or applicationId that is different from the package name indicated in AndroidManifest.xml in <manifest package="..."> tag, for example, to support different build variants: Add this in android/app/build.gradle

defaultConfig {
    ...
    resValue "string", "build_config_package", "YOUR_PACKAGE_NAME_IN_ANDROIDMANIFEST.XML"
}