How do I define a compile-time *only* classpath in Gradle?

There has been a lot of discussion regarding this topic, mainly here, but not clear conclusion.

You are on the right track: currently the best solution is to declare your own provided configuration, that will included compile-only dependencies and add to to your compile classpath:

configurations{
  provided
}

dependencies{
  //Add libraries like lombok, findbugs etc
  provided '...'
}

//Include provided for compilation
sourceSets.main.compileClasspath += [configurations.provided]

// optional: if using 'idea' plugin
idea {
  module{
    scopes.PROVIDED.plus += [configurations.provided]
  }
}

// optional: if using 'eclipse' plugin
eclipse {
  classpath {
    plusConfigurations += [configurations.provided]
  }
}

Typically this works well.

If you use the war plugin, providedCompile should do the trick. However if you need to exclude dependencies from being included in a jar, you'll have to extend the jar task. Below is an example for building a "fat jar" or "uber jar" (a single jar that includes all classes of its dependencies) excluding depndencies marked provided:

configurations {
    provided
    compile.extendsFrom provided
}

dependencies {
    provided "group.artifact:version"
    compile "group.artifact:version"
}

jar {
    dependsOn configurations.runtime
    from {
        (configurations.runtime - configurations.provided).collect {
            it.isDirectory() ? it : zipTree(it)
        }
    } 
}

Credit: http://kennethjorgensen.com/blog/2014/fat-jars-with-excluded-dependencies-in-gradle/

Update:

As of Gradle 2.12 the issue of defining compile only dependencies is finally solved in a simple and natural manner by the new "copmpileOnly" configuration:

dependencies {
    compileOnly 'javax.servlet:servlet-api:2.5'
}

I figured it out for my project setup. I use Android Studio running with the gradle plugin 0.9.+ with gradle 1.11 The main project uses amazon ads and amazon inapp purchases. It depends on a library project using amazon device messaging(ADM).

My main issue was with the the ADM where I got the "RuntimeException: Stub!" error.

1.) Library Project: The "provided configuration" proposed by Lukas does not work, as stated by him, so I used Richards approach, which however did not work as well out of the box. I had to change it a little since I could not find the lib in the ext_libs folder of the aar file. Gradle seems to pack all libraries in the libs folder in the in the final aar-file.

android.libraryVariants.all { variant ->
variant.packageLibrary.exclude( 'libs/amazon-device-messaging-1.0.1.jar' )
}

2.) Application Project : Here, the approach with the "provided configuration" worked.

configurations{
    provided
} 
dependencies {
    compile 'fr.avianey:facebook-android-api:+@aar'
    compile files('ext_libs/amazon-ads-5.3.22.jar')
    compile files('ext_libs/in-app-purchasing-1.0.3.jar' )
    provided files('ext_libs/amazon-device-messaging-1.0.1.jar')
}

android.applicationVariants.all {
    variant -> variant.javaCompile.classpath += configurations.provided
}

It's quite common to have runtime dependencies that aren't compile time dependencies. The other way around is a fairly special case and as such requires a few lines of configuration in Gradle. I suggest to search the Gradle forum for provided.

It sounds like what you are really after is declaring dependencies for your build, not for the compile class path. How this is done depends on how the desired functionality gets invoked (Ant task, Gradle task/plugin, ad-hoc use from build script). If you provide more detailed information on what you are trying to do, I can provide a more specific answer.

Here are some links to relevant information in the Gradle user guide:

• External dependencies for the build script
• Declaring the class path for a custom Ant task

If you use the WAR plugin, you can use providedCompile as in this example

dependencies {
    compile module(":compile:1.0") {
        dependency ":compile-transitive-1.0@jar"
        dependency ":providedCompile-transitive:1.0@jar"
    }
    providedCompile "javax.servlet:servlet-api:2.5"
    providedCompile module(":providedCompile:1.0") {
        dependency ":providedCompile-transitive:1.0@jar"
    }
    runtime ":runtime:1.0"
    providedRuntime ":providedRuntime:1.0@jar"
    testCompile "junit:junit:4.11"
    moreLibs ":otherLib:1.0"
}