Gradle plugins DSL: Restriction on declaration location

Question

I have a few Gradle scripts that get applied via apply from: 'my-build.gradle'. If I use the new plugins DSL as follows in the external build file my-build.gradle, it fails with the following error:

> startup failed:
  Only Project build scripts can contain plugins {} blocks
  See http://gradle.org/docs/2.3/userguide/plugins.html#sec:plugins_block 
  for information on the plugins {} block

Looking at the documentation pointed in the error message didn't reveal as to why the restriction is in place. Why is there a restriction on the location of the plugins declaration?

Files for reference below.

1. my-build.gradle file:

   plugins {
       id "net.saliman.cobertura" version "2.2.5"
   }
   

2. build.gradle file:

   apply from: "my-build.gradle"
   
   // Other stuff
   

Answer 1

I also faced similar issue recently and it got solved by changing Gradle settings in Intellij as follows:

Answer 2

This is how you can use plugins in external Gradle files such as your my-build.gradle:

buildscript {
  repositories {
    mavenCentral()
    maven { url "https://plugins.gradle.org/m2/" }
  }
  dependencies {
    classpath "org.sonarqube.gradle:gradle-sonarqube-plugin:1.1"
    classpath "net.saliman:gradle-cobertura-plugin:2.2.8"
  }
}
// Because this is a helper script that's sourced in from a build.gradle, we can't use the ID of external plugins
// We either use the full class name of the plugin without quotes or an init script: http://www.gradle.org/docs/current/userguide/init_scripts.html
apply plugin: org.sonarqube.gradle.SonarQubePlugin
apply plugin: net.saliman.gradle.plugin.cobertura.CoberturaPlugin

// rest of my-build.gradle omitted

Above I've activated the plugins for SonarQube and Cobertura.

Generally, to get the fully qualified class name of your plugin you will have to look inside its .jar file.

As for the technical reasons why you can't use a plugins {} block in an external file, I do not know. It might have to do something with the following:

[...] plugins [need to] be specified in a way that Gradle can easily and quickly extract [them], before executing the rest of the build script. It also requires that the definition of plugins to use be somewhat static.

But rejoice:

Future versions of Gradle will remove this restriction.