BuildKonfig

BuildConfig for Kotlin Multiplatform Project.
It currently supports embedding values from gradle file.

Table Of Contents

• Motivation
• Usage
  • Requirements
  • Gradle Configuration
  • Product Flavor?
  • Overwriting Values
• Supported Types
• Try out the sample

Motivation

Passing values from Android/iOS or any other platform code should work, but it's a hassle.
Setting up Android to read values from properties and add those into BuildConfig, and do the equivalent in iOS?
Rather I'd like to do it once.

Usage

Requirements

• Kotlin 1.5.0 or later
• Kotlin Multiplatform Project
• Gradle 6.5 or later

Gradle Configuration

Simple configuration

Kotlin DSL

import com.codingfeline.buildkonfig.compiler.FieldSpec.FieldValue.StringValue

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.21")
        classpath("com.netcosports:build-konfig:latest_version")
    }
}

plugins {
    kotlin("multiplatform")
    id("com.codingfeline.buildkonfig")
}

kotlin {
    // your target config...
    android()
    ios()
}

buildkonfig {
    packageName = "com.example.app"
    // objectName = "YourAwesomeConfig"
    // exposeObjectWithName = "YourAwesomePublicConfig"

    defaultConfigs {
        buildConfigField("name", StringValue("value"))
    }
}

• packageName Set the package name where BuildKonfig is being placed. Required.
• objectName Set the name of the generated object. Defaults to BuildKonfig.
• exposeObjectWithName Set the name of the generated object, and make it public.
• defaultConfigs Set values which you want to have in common. Required.

To generate BuildKonfig files, run generateBuildKonfig task.
This task will be automatically run upon execution of kotlin compile tasks.

Above configuration will generate following simple object.

// commonMain
package com.example.app

internal object BuildKonfig {
    val name: String = "value"
}

Configuring target dependent values

If you want to change value depending on your targets, you can use targetConfigs to define target-dependent values.

Kotlin DSL

import com.codingfeline.buildkonfig.compiler.FieldSpec.FieldValue.StringValue

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:1.5.21")
        classpath("com.netcosports:build-konfig:latest_version")
    }
}

plugins {
    kotlin("multiplatform")
    id("com.codingfeline.buildkonfig")
}

kotlin {
    // your target config...
    android()
    iosX64('ios')
}

buildkonfig {
    packageName = "com.example.app"

    // default config is required
    defaultConfigs {
        buildConfigField("name", StringValue("value"))
    }

    targetConfigs {
        // names in create should be the same as target names you specified
        create("android") {
            buildConfigField("name2", StringValue("value2"))
        }

        create("ios") {
          buildConfigField("name", StringValue("valueNative"))
        }
    }
}

• packageName Set the package name where BuildKonfig is being placed. Required.
• objectName Set the name of the generated object. Defaults to BuildKonfig.
• exposeObjectWithName Set the name of the generated object, and make it public.
• defaultConfigs Set values which you want to have in common. Required.
• targetConfigs Set target specific values as closure. You can overwrite values specified in defaultConfigs.
• buildConfigField(String type, String name, Any value) Add new value or overwrite existing one.
• buildConfigNullableField((String type, String name, Any value) Add new nullable value or overwrite existing one.

Product Flavor?

Yes(sort of).
Kotlin Multiplatform Project does not support product flavor. Kotlin/Native part of the project has release/debug distinction, but it's not global.
So to mimick product flavor capability of Android, we need to provide additional property in order to determine flavors.

Specify default flavor in your gradle.properties

# ROOT_DIR/gradle.properties
buildkonfig.flavor=dev

Kotlin DSL

import com.codingfeline.buildkonfig.compiler.FieldSpec.FieldValue.StringValue
import com.codingfeline.buildkonfig.gradle.TargetConfigDsl

buildkonfig {
    packageName = "com.example.app"

    // default config is required
    defaultConfigs {
        buildConfigField("name", StringValue("value"))
    }
    // flavor is passed as a first argument of defaultConfigs 
    defaultConfigs("dev") {
        buildConfigField("name", StringValue("devValue"))
    }

    targetConfigs(closureOf<NamedDomainObjectContainer<TargetConfigDsl>> {
        create("android") {
            buildConfigField("name2", StringValue("value2"))
        }

        create("ios") {
            buildConfigField("name", StringValue("valueIos"))
        }
    })
    // flavor is passed as a first argument of targetConfigs
    targetConfigs("dev", closureOf<NamedDomainObjectContainer<TargetConfigDsl>> {
        create("ios") {
            buildConfigField("name", StringValue("devValueIos"))
        }
    })
}

In a development phase you can change value in gradle.properties as you like.
In CI environment, you can pass value via CLI $ ./gradlew build -Pbuildkonfig.flavor=release

Overwriting Values

If you configure same field across multiple defaultConfigs and targetConfigs, flavored targetConfigs is the strongest.

Lefter the stronger.

Flavored TargetConfig > TargetConfig > Flavored DefaultConfig > DefaultConfig

Supported Types

• String
• Int
• Long
• Float
• Boolean
• List

Try out the sample

Have a look at ./sample directory.

# Publish the latest version of the plugin to mavenLocal()
$ ./gradlew publishToMavenLocal

# Try out the samples.
# BuildKonfig will be generated in ./sample/build/buildkonfig
$ ./gradlew -p sample generateBuildKonfig