ANDROID.md

Android Setup

The following steps are required for Android

You need to manually apply a plugin to your app, from android/app/build.gradle:

Right below apply from: "$flutterRoot/packages/flutter_tools/gradle/flutter.gradle"

add the following line:

apply from: project(':flutter_config').projectDir.getPath() + "/dotenv.gradle"

Building a release version

When building your apk for release, the R8 code shrinker obfuscates the BuildConfig class which holds all the env variables and thus causes all the env variables to be null. To prevent this, the following has to be done:

1. Add file android/app/proguard-rules.pro to your app's project.
2. Add the below line to the newly created proguard-rules.pro file:

   -keep class com.yourcompany.app.BuildConfig { *; }
   

   where com.yourcompany.app should be replaced with your app's package name.

Usage in Java/Kotlin Code

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

fun getApiClient(): HttpURLConnection {
    val url = URL(BuildConfig.API_URL);
    // ...
}

Usage in Gradle

You can read environment varibles from your Gradle configuration:

defaultConfig {
    applicationId project.env.get("APP_ID")
}

Usage in XML files

You can use env variables to configure libraries in AndroidManifest.xml and other xml files:

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

Different environments

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

The same environment variable can be used to assemble releases with a different config:

$ cd android && ENVFILE=.env.staging ./gradlew assembleRelease

Alternatively, you can define a map in build.gradle associating builds with env files. Do it before the apply from call, and use build cases in lowercase, like:

project.ext.envConfigFiles = [
    debug: ".env.development",
    release: ".env.production",
    anothercustombuild: ".env",
]

apply from: project(':flutter_config').projectDir.getPath() + "/dotenv.gradle"

Different Package Names

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"
}

Note

All variables are strings, so you may need to cast them. For instance, in Gradle:

versionCode project.env.get("VERSION_CODE").toInteger()

Once again, remember variables stored in .env are published with your code, so DO NOT put anything sensitive there like your app signingConfigs.

This plugin is written in Kotlin. Therefore, you need to make sure you have Kotlin support in your project your project. See installing the Kotlin plugin.

Edit your project-level build.gradle file to look like this:

buildscript {
    ext.kotlin_version = '1.3.31'
    ...
    dependencies {
        ...
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
    }
}
...

Edit your app-level build.gradle file to look like this:

apply plugin: 'kotlin-android'
...
dependencies {
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
    ...
}

You also need to make sure you are on the latest version of gradle