Gradle: package multi-project into a single jar

fatjargradle

I have a gradle multi-project and want to create a single jar (library) containing all the classes of my subprojects and external dependencies.

I have the following project structure. Each project has its own 3rd party dependencies. Common dependencies are included in the root project. The two modules A and B are dependent on the core.

+ root-project (only build.gradle and settings.gradle)
  - core       (src/main/java, src/main/resources, ..)
  - module-A   (src/main/java, src/main/resources, ..)
  - module-B   (src/main/java, src/main/resources, ..)

To export a single jar, I added the following task to the build.gradle of the root project:

apply plugin: "java"

subprojects.each { subproject -> evaluationDependsOn(subproject.path)}

task allJar(type: Jar, dependsOn: subprojects.jar) {
    baseName = 'multiproject-test'
    subprojects.each { subproject ->
        from subproject.configurations.archives.allArtifacts.files.collect {
            zipTree(it)
        }
    }
}

artifacts {
    archives allJar
}

This approach works, but does only collect the project source files. The 3rd party dependencies are ignored. So I tried out the Shadow Plugin (http://imperceptiblethoughts.com/shadow/) which should also include external dependencies.

Unfortunately the plugin does not collect anything at all. This is most probably due to missing dependencies between the root project and its sub projects. How can I tell the shadow plugin, that it should collect the sources of the subprojects? Or is there a better approach to export a single library out of multiple projects?

complete build.gradle using the shadow plugin:

/****************************************
 * instructions for all projects
 ****************************************/
allprojects {
    apply plugin: 'idea'
    apply plugin: 'eclipse'

    group = 'com.test.multi-project'
    version = '1.0'
}

/****************************************
 * instructions for each sub project
 ****************************************/
subprojects {
    apply plugin: "java"

    sourceCompatibility = 1.9
    targetCompatibility = 1.9

    repositories {
        mavenCentral()
    }

    dependencies {
        compile "org.slf4j:slf4j-api:1+"
        compile "ch.qos.logback:logback-core:1+"
        compile "ch.qos.logback:logback-classic:1+"

        testCompile "junit:junit:4+"
    }
}

/****************************************
 * Single jar out of all sub projects
 ****************************************/
buildscript {
    repositories {
        jcenter()
    }
    dependencies {
        classpath 'com.github.jengelman.gradle.plugins:shadow:2.0.2'
    }
}

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

shadowJar {
    baseName = 'multiproject-test'
}

The submodules are included in the settings.gradle of the root project

rootProject.name = 'myproject-root'

// submodules
include ":core"

include ":module-A"
include ":module-B"

Thanks for your help!

Best Answer

I solve my problem with the solution explained here: https://discuss.gradle.org/t/how-to-get-gradle-install-to-actually-bundle-all-project-subproject-classes-resources-etc/12070/4

My build.gradle looks now like this:

/****************************************
 * instructions for all projects
 ****************************************/
allprojects {
    apply plugin: 'idea'
    apply plugin: 'java'

    repositories {
        mavenCentral()
    }

    group = 'com.test.multiproject'
    version = '1.0'

    sourceCompatibility = 1.9
    targetCompatibility = 1.9
}

/****************************************
 * instructions for each sub project
 ****************************************/
subprojects {

    // common dependencies
    dependencies {
        compile "org.slf4j:slf4j-api:1+"
        compile "ch.qos.logback:logback-core:1+"
        compile "ch.qos.logback:logback-classic:1+"

        testCompile "junit:junit:4+"
    }
}

/****************************************
 * Single library jar containing all sub projects and 3rd party dependencies
 ****************************************/
configurations {
    childJars
}

dependencies {
    subprojects.each {
        childJars project(it.path)
    }
}

jar {
    dependsOn configurations.childJars
    from { configurations.childJars.collect { zipTree(it) } }
}

Related Solutions

Gradle multi project build with empty projects

You can try using the trick they use in Gradle's own settings.gradle file. Note how each of the sub projects are located in the 'subprojects/${projectName}' folder, but the subprojects folder itself is not a project.

So in your case you'd do something like:

include "source:compA-api"
include "source:compA-core"
include "source:compB"

project(':source:compA-api').projectDir = new File(settingsDir, 'source/compA/api')
project(':source:compA-core').projectDir = new File(settingsDir, 'source/compA/core')

I have intentionally omitted the colon between compA and api to make sure source:compA does not get evaluated as a project container.

Alternatively, you can try excluding the source:compA project from having the java plugin applied to it, by doing something like:

def javaProjects() { 
  return subprojects.findAll { it.name != 'compA' }
} 

configure(javaProjects()) { 
  apply plugin: 'java' 
}

Edit: Alternatively you can try something like this (adjust to your liking):

def javaProjects() { 
  return subprojects.findAll { new File(it.projectDir, "src").exists() }
} 

configure(javaProjects()) { 
  apply plugin: 'java' 
}

Gradle – Multiple settings gradle files for multiple projects building

I was able to solve this problem in a relatively clean way. Improvements are certainly welcome!

Although Gradle does not support multiple settings.gradle scripts out of the box, it is possible to create individual sub-projects each with their own settings.gradle file. Let's say you have multi-project A that depends on multi-project B, each with their own sub-projects. Your directory structure might look like:

A
- settings.gradle
- foo
- faz
\ B
  - settings.gradle
  - bar
  - bap

Out of the box, Gradle expects A/settings.gradle to look something like this:

include ':foo', ':faz', 'B:bar', 'B:bap'

The problem with this is that every time B adds a new project, A/settings.gradle must also change even if the new project is only used by B. To avoid this situation, you could try to apply B/settings.gradle in A/settings.gradle instead of adding redundant declarations:

apply from: 'B/settings.gradle'
include ':foo', ':faz'

If you try this, you'll find that Gradle fails because it generates the wrong projectDir for :bar and :bap. It mistakenly assumes that B's includes are relative to settingsDir which happens to be A/ when Gradle is invoked from that project root. To fix this you can add another script such as B/settings-parent.gradle (the exact name is not significant):

apply from: 'settings.gradle'

def updateProjectPaths(Set<ProjectDescriptor> projects) {
    projects.each { ProjectDescriptor project ->
        String relativeProjectPath = project.projectDir.path.replace(settingsDir.path, "")
        project.projectDir = new File("B/$relativeProjectPath")
        // Recursively update paths for all children
        updateProjectPaths(project.children)
    }
}

updateProjectPaths(rootProject.children)

This strips settingsDir.path and prefixes the path with B/. This can be extended to multiple layers of settings[-parent].gradle files by having each layer add itself onto the path. Now you will apply this script to A/settings.gradle:

apply from: 'B/settings-parent.gradle'
include ':foo', ':faz'

With this scheme, new B projects do not unnecessarily break A/settings.gradle and all projects can be used without explicitly referencing the B sub-project. For example, if ':foo' wanted to use 'B:bap', it may simply declare:

compile project(':bap')

Best Answer

Related Solutions

Gradle multi project build with empty projects

Gradle – Multiple settings gradle files for multiple projects building

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