# Composite Builds Basics Sample

version 7.3

- Groovy DSL

- Kotlin DSL

| You can open this sample inside an IDE using the IntelliJ native importer or Eclipse Buildship.

## Defining and using a composite build

This sample shows how 2 Gradle builds that are normally developed separately and combined using binary integration can be wired together into a composite build with source integration. The `my-utils` multiproject build produces 2 different java libraries, and the `my-app` build produces an executable using functions from those libraries.

Note that the `my-app` build does not have direct dependencies on `my-utils`. Instead, it declares module dependencies on the libraries produced by `my-utils`:

my-app/app/build.gradle

    plugins {
        id 'application'
    }

    application {
        mainClass = 'org.sample.myapp.Main'
    }

    dependencies {
        implementation 'org.sample:number-utils:1.0'
        implementation 'org.sample:string-utils:1.0'
    }

my-app/app/build.gradle.kts

    plugins {
        id("application")
    }

    application {
        mainClass.set("org.sample.myapp.Main")
    }

    dependencies {
        implementation("org.sample:number-utils:1.0")
        implementation("org.sample:string-utils:1.0")
    }

## Using command-line composite build

When using a composite build, no shared repository is required for the builds, and no changes need to be made to the build scripts.

1. Change the sources of `Number.java`

2. Run the `my-app` application, including the `my-utils` build.

    cd my-app
    gradle --include-build ../my-utils run

Using dependency substitution, the module dependencies on the util libraries are replaced by project dependencies on `my-utils`.

## Converting `my-app` to a composite build

It’s possible to make the above arrangement persistent, by making `my-app` a composite build that includes `my-utils`.

    cd my-app
    echo "includeBuild '../my-utils'" >> settings.gradle
    gradle run

With this configuration, the module dependencies from `my-app` to `my-utils` will always be substituted with project dependencies.

While simple, this approach has the downside of modifying the `my-app` build.

## Using separate composite build

It is also possible to create a separate composite build that includes both the `my-app` and `my-utils` builds.

settings.gradle

    rootProject.name = 'my-composite'

    includeBuild 'my-app'
    includeBuild 'my-utils'

settings.gradle.kts

    rootProject.name = "my-composite"

    includeBuild("my-app")
    includeBuild("my-utils")

Note that it is not yet possible to execute tasks in an included build from the command line. Instead, the build user must create delegating tasks in the composite.

build.gradle

    tasks.register('run') {
        dependsOn gradle.includedBuild('my-app').task(':app:run')
    }

build.gradle.kts

    tasks.register("run") {
        dependsOn(gradle.includedBuild("my-app").task(":app:run"))
    }

    gradle run

We are working on a mechanism to permit tasks in included builds to be referred to directly on the command line. Stay tuned!