Use Spring Boot as a transitive dependency from a common library

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1

I have a common library that is published as a jar to maven local, which is then used by a set of very thin client applications. These applications basically feed their own configuration to the common library and initializes themselves as Spring applications.

This common library uses spring boot and a bunch of other dependencies. My question is, is it possible for me to not define spring boot as a dependency in the applications, and simply use the common library’s spring version as a transitive dependency in all the applications?

I feel like this should be possible, but when I tried doing it, the springframework.org.boot classes are not being resolved (eg: @SpringBootApplication annotation).

These are my build.gradle files:

build.gradle from the common library

plugins {
    id 'java-library'
    id 'maven-publish'
}

group 'com.my.group'
version '1.0-SNAPSHOT'

sourceCompatibility = '11'

repositories {
    mavenLocal()
}

publishing {
    publications {
        mavenJava(MavenPublication) {
            groupId = 'com.my.group'
            artifactId = 'common-lib'
            version = '0-alpha.1'

            from components.java
        }
    }
}

configurations {
    springBom
    compileOnly.extendsFrom(springBom)
    annotationProcessor.extendsFrom(springBom)
    implementation.extendsFrom(springBom)
}

dependencies {
    springBom enforcedPlatform('org.springframework.boot:spring-boot-dependencies:2.3.5.RELEASE')

    api 'org.springframework.boot:spring-boot-starter'
    implementation 'org.springframework.boot:spring-boot-starter-validation'
    implementation 'org.springframework.boot:spring-boot-starter-jdbc'
    implementation 'org.springframework.cloud:spring-cloud-aws-messaging'

    annotationProcessor 'org.springframework.boot:spring-boot-autoconfigure-processor'
    annotationProcessor 'org.springframework.boot:spring-boot-configuration-processor'
    
    // a few other non-spring dependencies
}

build.gradle from a sample application

plugins {
	id 'java'
}

group = 'com.my.group'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'

repositories {
	mavenLocal()
}

dependencies {
	implementation group: 'com.my.group', name: 'common-lib', version: '0-alpha.1'
}

Example application initialization

package com.my.group.Core;
// none of the below are resolved
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.ApplicationArguments;
import org.springframework.boot.ApplicationRunner;
import org.springframework.boot.SpringApplication;

@SpringBootApplication(scanBasePackages = {"com.my.group"})
public class ConsumerApplication implements ApplicationRunner {

	@Autowired
	Core core;

	public ConsumerApplication() {
	}

	public static void main(String[] args) {
		SpringApplication.run(ConsumerApplication.class, args);
	}

	@Override
	public void run(ApplicationArguments args) {
		try {
			core.processEvents();
		} catch (ConfigurationException | InitializationException e) {
			e.printStackTrace();
		}
	}
}

If I add in the following dependencies to my applications, everything works as expected.

springBom enforcedPlatform('org.springframework.boot:spring-boot-dependencies:2.3.5.RELEASE')
implementation 'org.springframework.boot:spring-boot-starter'
2

I found the issue. I have not included api in the configurations and as a result, the application could not resolve the version. Fixed by updating the build.gradle in my common library like so:

configurations {
springBom
compileOnly.extendsFrom(springBom)
annotationProcessor.extendsFrom(springBom)
implementation.extendsFrom(springBom)
api.extendsFrom(springBom)
}