How to load Gradle Plugin (with its depenecies) into build.gradle?

Question

I have a project that has two gradle files: build.gradle and myPlugin.gradle

The myPlugin.gradle implemented the Plugin Interface. The plugin also has a dependency on osdetector-gradle-plugin

I added the two gradle files beside each other then I tried to apply myPlugin into build.gradle as follows:

apply from: 'myPlugin.gradle'

However, I have got the following error in myPlugin.gradle file:

Plugin with id 'com.google.osdetector' not found

Here is the code for myPlugin.gradle file:

apply plugin: 'groovy'
apply plugin: 'maven'

  repositories {
     mavenCentral()
     mavenLocal()
  }
  dependencies {
      compile   'com.google.gradle:osdetector-gradle-plugin:1.4.0'
  }

import org.gradle.api.tasks.TaskAction
import org.gradle.api.DefaultTask
import org.gradle.api.Plugin
import org.gradle.api.Project

apply plugin: 'com.google.osdetector'
apply plugin: HostingMachineOSPlugin

class HostingMachineOSPlugin implements Plugin<Project>{
    void apply(Project project){
        project.plugins.apply("com.google.osdetector");
        //project.configurations.files('com.google.osdetector')
        println project.osdetector.os

        /* Extend the project property to have the class HostingMachineOS */
        project.ext.HostingMachineOS = HostingMachineOS
    }
}

public class HostingMachineOS {

    static family = "Unkown"

    static def setFamilyName(name){
        family = name
    }

    static def isLinux (){
        family == "linux"
    }

    static def isWindows (){
        family == "windows"
    }

    static def isMacOS(){
        family == "osx"
    }
}

HostingMachineOS.setFamilyName(osdetector.os)

in build.gradle file: I am just doing something like this:

//define buildScript repositories and dependencies then

apply from: 'myPlugin.gradle'

task dummy{
  println HostingMachineOS.isMacOS()
  println HostingMachineOS.isLinux()
  println HostingMachineOS.isWindows()
}

How can I solve the Plugin with id 'com.google.osdetector' not found?

Answer 1

This is a common pitfall, to add a plugin to build.gradle file you need to add a dependency for the build script itself - not for the project. The following piece of code (added in the file where you apply the plugin) should solve the problem:

buildscript {

  repositories {
     mavenCentral()
     mavenLocal()
  }

  dependencies {
     classpath 'com.google.gradle:osdetector-gradle-plugin:1.4.0'
  } 

}

EDIT

Please have a look here - it seems that if you need to apply from third-party script you need to use the full class name (with package). So the files should be defined as follows:

build.gradle

apply from: 'myPlugin.gradle'

task dummy{
  println HostingMachineOS.isMacOS()
  println HostingMachineOS.isLinux()
  println HostingMachineOS.isWindows()
}

myPlugin.gradle

buildscript {
  repositories {
    mavenCentral()
  }
  dependencies {
    classpath 'com.google.gradle:osdetector-gradle-plugin:1.4.0'
  }
}

apply plugin: 'groovy'
apply plugin: 'maven'
apply plugin: com.google.gradle.osdetector.OsDetectorPlugin
apply plugin: HostingMachineOSPlugin

class HostingMachineOSPlugin implements Plugin<Project>{
    void apply(Project project){
        project.plugins.apply(com.google.gradle.osdetector.OsDetectorPlugin);
        //project.configurations.files('com.google.osdetector')
        println project.osdetector.os

        /* Extend the project property to have the class HostingMachineOS */
        project.ext.HostingMachineOS = HostingMachineOS
    }
}

public class HostingMachineOS {

    static family = "Unkown"

    static def setFamilyName(name){
        family = name
    }

    static def isLinux (){
        family == "linux"
    }

    static def isWindows (){
        family == "windows"
    }

    static def isMacOS(){
        family == "osx"
    }
}

HostingMachineOS.setFamilyName(osdetector.os)