Project Hierarchy

.
├── acme-utils
│   ├── build.gradle.kts
│   └── src
├── acme-domain
│   ├── build.gradle.kts
│   └── src
├── acme-repository
│   ├── build.gradle.kts
│   └── src
├── acme-security
│   ├── build.gradle.kts
│   └── src
├── acme-app-runner
│   ├── build.gradle.kts
│   └── src
├── buildSrc
│   ├── build
│   ├── build.gradle.kts
│   └── src
│       └── main
│           └── kotlin
│               └── com.acme.common-conventions.gradle.kts
├── gradle
│   └── wrapper
├── gradlew
├── gradlew.bat
├── settings.gradle.kts

Shared Convention Plugin Configuration

The file buildSrc/src/main/kotlin/com.acme.common-conventions.gradle.kts establishes the baseline setup for all subprojects.

plugins {
    `java-library`
    `maven-publish`
    id("org.springframework.boot")
}

apply(plugin = "io.spring.dependency-management")

tasks.named<org.springframework.boot.gradle.tasks.bundling.BootJar>("bootJar") {
    mainClass.set("com.acme.MainApplication")
}

repositories {
    mavenLocal()
    flatDir {
        dirs("lib")
    }
    maven {
        url = uri("https://maven.aliyun.com/repository/public/")
    }
    maven {
        url = uri("https://oss.sonatype.org/content/repositories/snapshots/")
    }
    maven {
        url = uri("https://repo.jenkins-ci.org/releases")
    }
    maven {
        url = uri("https://repo.maven.apache.org/maven2/")
    }
}

dependencies {
    // shared dependencies
}

group = "com.acme"
version = "2.0.0"
java.sourceCompatibility = JavaVersion.VERSION_17

publishing {
    publications.create<MavenPublication>("maven") {
        from(components["java"])
    }
}

tasks.withType<JavaCompile>() {
    options.encoding = "UTF-8"
}

Entry Point Module Setup

The acme-app-runner/build.gradle.kts module handles the executable artifact and isolates the library dependencies.

plugins {
    id("com.acme.common-conventions")
}

val depsDir = layout.buildDirectory.dir("dependencies")

// Task to isolate runtime classpath jars
tasks.register<Copy>("isolateLibs") {
    delete(depsDir)
    from(configurations.runtimeClasspath)
    into(depsDir)
}

tasks.named<org.springframework.boot.gradle.tasks.bundling.BootJar>("bootJar") {
    excludes.set(listOf("*.jar"))
    dependsOn("isolateLibs")

    manifest {
        attributes(
            "Class-Path" to configurations.runtimeClasspath.get().files.joinToString(" ") { "dependencies/${it.name}" }
        )
    }
}

dependencies {
    implementation(project(":acme-utils"))
    implementation(project(":acme-domain"))
    implementation(project(":acme-repository"))
    implementation(project(":acme-security"))
}

description = "Main Application Runner"

Build Output and Caveats

Executing the bootJar task will generate the primary executable archive and place all external libraries into the build/dependencies directory.

A notable drawback of this configurasion is that intra-project modules are packaged as *-plain.jar archives, meaning they do not bundle their own transitive dependencies. When deploying patches, simply swapping out a module's plain jar works if only internal logic changed. However, introducing or removing an external library dependency in a module requires manually updating the isolated dependency folder.