How to Read Properties Defined in Local.Properties in Build.Gradle

How do I read properties defined in local.properties in gradle.properties

This won't happen, because Java Properties are simple strings, there is no logic applied automatically.

However, you can simply use a gradle.properties file in the .gradle folder of your user home directory to define environment-related settings instead of project-related settings. This file won't be uploaded to a VCS.

Gradle property in local.properties

As in https://docs.gradle.org/current/userguide/build_environment.html#sec:gradle_configuration_properties described you could use a grade.properties file in your GRADLE_USER_HOME directory (default $HOME/.gradle).

How to read a properties files and use the values in project Gradle script?

If using the default gradle.properties file, you can access the properties directly from within your build.gradle file:

gradle.properties:

applicationName=Admin
projectName=Hello Cool

build.gradle:

task printProps {
    doFirst {
        println applicationName
        println projectName
    }
}

If you need to access a custom file, or access properties which include . in them (as it appears you need to do), you can do the following in your build.gradle file:

def props = new Properties()
file("build.properties").withInputStream { props.load(it) }

task printProps {
    doFirst {
        println props.getProperty("application.name")
        println props.getProperty("project.name")
    }
}

Take a look at this section of the Gradle documentation for more information.

Edit

If you'd like to dynamically set up some of these properties (as mentioned in a comment below), you can create a properties.gradle file (the name isn't important) and require it in your build.gradle script.

properties.gradle:

ext {
    subPath = "some/sub/directory"
    fullPath = "$projectDir/$subPath"
}

build.gradle

apply from: 'properties.gradle'

// prints the full expanded path
println fullPath

Read value from local.properties via Kotlin DSL

Okay. I found solutions.

For Android Projects :

In my build.gradle.kts I create a value that retrieves my key:

import com.android.build.gradle.internal.cxx.configure.gradleLocalProperties

val key: String = gradleLocalProperties(rootDir).getProperty("key")

And in the block buildTypes I write it:

buildTypes {
 getByName("debug") {
    buildConfigField("String", "key", key)
   }
}

And in my Activity now I can retrieve this value:

override fun onCreate() {
    super.onCreate()
    val key = BuildConfig.key
}

For Kotlin Projects:

We can create an extension that help us to retrieve desired key:

fun Project.getLocalProperty(key: String, file: String = "local.properties"): Any {
    val properties = java.util.Properties()
    val localProperties = File(file)
    if (localProperties.isFile) {
        java.io.InputStreamReader(java.io.FileInputStream(localProperties), Charsets.UTF_8).use { reader ->
            properties.load(reader)
        }
    } else error("File from not found")

    return properties.getProperty(key)
}

And use this extension when we would like

task("printKey") {
   doLast {
       val key = getLocalProperty("key")
       println(key)
   }
}

setting property read from local.properties inside build.gradle

The error you're getting is correct. To set a property you need to use ext. Please have a look at the docs.

So the following piece of code will do the job:

File secretPropsFile = file('./local.properties')
if (secretPropsFile.exists()) {
    Properties p = new Properties()
    p.load(new FileInputStream(secretPropsFile))
    p.each { name, value ->
        ext[name] = value
    }
} else {
    throw new IllegalStateException("secret.properties could not be located for build process")
}

println project.nexusPassword
println project.nexusUsername //property is set in project's scope via ext