Small post today. We use a large multimodule Spring Boot 1.x project at work. I’ve been transitioning this to Gradle over the past few months. Initially I had created the build.gradle.kts using compile and testCompile configurations, but a fellow dev requested that I update to implementation. I had been waiting to do this because I knew it would cause issues, but it still needed to be done.

Promptly after doing so I began receiving reports that the runnable jar was way too small. I investigated and it appeared that only the deploy module was being included in the runnable.

Here is a diagram of our module setup

root
|- module1
|- common
|- common-test
|- module2-common
|- module2-write
|- module3-common
|- module3-write
|- module4
|- module5
|- deploy

these all have dependencies on each other, but the main deploy module is what we’re worried about. It has these dependencies:

deploy/build.gradle.kts
    implementation(project(":common"))
    implementation(project(":module1"))
    implementation(project(":module2-common"))
    implementation(project(":module2-write"))
    implementation(project(":module3-common"))
    implementation(project(":module3-write"))
    implementation(project(":module4"))
    implementation(project(":module5"))
    testImplementation(project(":common-test"))

The main deploy module will build a runnable Spring Boot 1.x jar into the deploy/build/libs folder. The deploy module will be a repackaged version of all of the other modules.

Changing from compile to implementation actually causes the spring boot plugin to fail to package all the other modules, due to this comment

As noted in that comment, the solution is to create a custom configuration for the bootRepackage task.

configurations {
    custom {
        it.extendsFrom implementation
    }
}

bootRepackage {
    customConfiguration = 'implementation'
}

but, with the kotlin dsl it’s a bit different! The solution is still pretty simple though.

val implementation = configurations.getByName("implementation")
configurations.create("includeAllJars") {
    this.extendsFrom(implementation)
}
withType<BootJar> {
    this.setCustomConfiguration("includeAllJars")
}