Shadow is an extension of the Gradle Jar task that optimizes FatJar/UberJar creation by using JarInputStream and JarOutputStream to copy file contents. This avoids the unnecessary I/O overhead of expanding jar files to disk before recombining them. Shadow provides the similar filtering, relocation, and transformation capabilities as the Maven Shade plugin. Starting with version 0.9, Shadow is a complete re-write based on core Gradle classes and concepts instead of a port of the Maven Shade code. Documentation for version 0.8 and prior can be found here

buildscript {
  repositories { jcenter() }
  dependencies {
    classpath 'com.github.jengelman.gradle.plugins:shadow:1.0.2'
  }
}

apply plugin: 'java' // or 'groovy'. Must be explicitly applied
apply plugin: 'com.github.johnrengelman.shadow'

Note: Applying the ShadowPlugin to a project applies the majority of its settings via a callback on the application of other plugins. For example, the bulk of shadow is only added to the project if the java or groovy plugins are also added. Shadow will not add them automatically, but instead listens for their application and responds.

$ gradle shadowJar //shadow the runtime configuration with project code into ./build/libs/

shadowJar by uses the same default configurations as jar and additionally configures the classifier to be "all". Additionally, it creates a 'shadow' configuration and assigns the jar as an artifact of it. This configuration can be used to add dependencies that are excluded from the shadowing.

apply plugin: 'application'
apply plugin: 'com.github.johnrengelman.shadow'

Applying both shadow and application to a project will create a number of additional tasks to be created. These tasks mimic the application plugin but execute using the output of the shadowJar task.

Applying the application plugin will cause the shadowJar to include the Main-Class attribute in the manifest of the shadowJar output. This is configured via the mainClassName attribute from the application plugin

By default, uses the same manifest as the Jar task.

jar {
  manifest {
    attributes("Implementation-Title": "Gradle", "Implementation-Version": version)
  }
}

Append to the Jar MANIFEST

shadowJar {
  appendManifest {
    attributes 'Test-Entry': 'PASSED'
  }
}

Replace the Jar MANIFEST

shadowJar {
  manifest {
    attributes("Implementation-Title": "Gradle", "Implementation-Version": version)
  }
}

shadowJar {
  mergeServiceFiles()
}

OR

import com.github.jengelman.gradle.plugins.shadow.transformers.ServiceFileTransformer

shadowJar {
  transform(ServiceFileTransformer)
}

shadowJar {
  append('NOTICE')
}

OR

import com.github.jengelman.gradle.plugins.shadow.transformers.AppendingTransformer

shadowJar {
  transform(AppendingTransformer) {
    resource = 'NOTICE'
  }
}

shadowJar {
  exclude 'LICENSE'
}

Exclude specific dependency (transitive dependencies are not excluded)

shadowJar {
  dependencies {
    exclude(dependency('asm:asm:3.3.1'))
  }
}

Include specific dependency (transitive dependencies are not included). Note that dependency inclusion is based on the same core classes as Gradle's CopySpec inclusion/exclusion. By default, there is a global include, however, declaring a specific include effectively creates a global exclude. That is once an include is made, only items that are specifically listed for inclusion will be include in the final output.

shadowJar {
  dependencies {
    include(dependency('asm:asm:3.3.1'))
  }
}

Exclude a project dependency in a multi-project build

shadowJar {
  dependencies {
    exclude(project(":myclient"))
  }
}

shadowJar {
  relocate 'org.objectweb.asm', 'myjarjarasm.asm'
}

shadowJar {
  relocate('org.objectweb.asm', 'myjarjarasm.asm') {
    exclude 'org.objectweb.asm.ClassReader'
  }
}

Uses the Transformer interface.

shadowJar {
  transform(<Transformer class>) {
    //..configure the Transformer class instance
  }
}

apply plugin: 'com.github.johnrengelman.shadow'
apply plugin: 'maven-publish'

publishing {
  publications {
    shadow(MavenPublication) {
      from components.java
      artifact shadowJar
    }
  }
}

apply plugin: 'com.github.johnrengelman.shadow'
apply plugin: 'maven-publish'

shadowJar {
  baseName = 'myproject-all'
  classifier = ''
}

publishing {
  publications {
    shadow(MavenPublication) {
      from components.shadow
      artifactId = 'myproject-all'
    }
  }
}

dependencies {
  compile 'asm:asm:3.3.1'
  compile 'org.bouncycastle:bcprov-jdk15on:1.47'
  shadow 'org.bouncycastle:bcprov-jdk15on:1.47'
}

shadowJar {
  dependencies {
    exclude(dependency('org.bouncycastle:bcprov-jdk15on:1.47'))
  }
}

This examples allows the project to compile against the BouncyCastle encryption library, but then excludes it from the shadowed jar, but including it as a dependency on the 'shadow' configuration.

Additionally, any dependencies added to the shadow configuration will be added to the Class-Path attribute in the JAR Manifest for the output of shadowJar.

ChangeLog